Overcoming barriers to micro-scale greening in rapidly urbanizing Sub-Saharan African cities: empirical insights from Ghana

Abstract

Urban greening efforts in private and semi-public realms can complement state-led initiatives, which have traditionally centred on public green spaces (macro-scale). In the Global South, citizens tend to place significant importance on the co-benefits of Nature-based Solutions (NbS) such as food, water and aesthetic value. This study uses the Greater Kumasi Metropolitan Area, Ghana, to provide insights into leveraging NbS co-benefits to promote micro-scale NbS (e.g., vertical gardens) adoption. We conducted correspondence analysis to identify preferred NbS co-benefits and determine suitable measures for different neighbourhoods. We also explored factors that hinder or enable micro-scale NbS uptake and analysed their correlations to identify the most impactful factors. Key strategies for increasing micro-scale NbS adoption include leveraging existing greening policies, diversifying funding, including engaging the private sector, enhancing stakeholder coordination and capacity-building in landscape design. This tailored approach offers insights for expanding citizen-led NbS in rapidly urbanising regions of the Global South.

Introduction

Amid the worsening climate crisis and increasing frequency of natural hazards, researchers and policymakers globally are increasingly turning to nature-based approaches as cost-effective, multifunctional solutions for resilience and sustainability¹. Nature-based Solutions (NbS) serve as the umbrella concept for such approaches, including ecosystem-based adaptation and green infrastructure, and are broadly defined as “solutions that are inspired and supported by nature, which are cost-effective, simultaneously provide environmental, social and economic benefits and help build resilience”².

NbS have been integrated into the national adaptation plans of 62% of countries worldwide³ and major policy frameworks. For example, the European Commission’s Nature Restoration Law and Horizon Research and Innovation program⁴ and the United States’ federal climate agenda⁵ are explicitly promoting NbS implementation. In the Global South, the African Union’s Climate Change and Resilient Development Strategy 2022–2032, the Green Recovery Action Plan 2021–2027 and Agenda 2063: The Africa We Want likewise signal political recognition of NbS as part of Africa’s adaptation and sustainable development aspirations.

The widespread policy orientation toward NbS is expected to accelerate implementation across multiple spatial scales⁶. At the macro-scale, landscape-wide measures such as protected areas, reforestation and watershed restoration target entire ecosystems; at the meso-scale, neighbourhood-level interventions such as parks, community gardens and green corridors provide public greening; and at the micro-scale, site-specific measures like permeable pavements, courtyard greenery or green roofs modify individual plots and buildings⁷. While large- (and some meso-) scale interventions often attract policy and funding attention (e.g., Room for the River in Netherlands which cost €2.2 billion from 2006 to 2015)⁸, micro-scale NbS are particularly critical in densely built, rapidly urbanising contexts where land for public greening is scarce^9,10. Flood mitigation is a dominant rationale for NbS, and even at the micro-scale, their effectiveness is well documented in literature. Shrubs can reduce runoff by up to 57%¹¹, trees can increase infiltration rates by 18–153% (Bartens et al.¹²; Zhang et al.¹³), permeable pavements can lower peak outflow by 51 L/m^{2 14} and green roofs can retain 49–83% of stormwater (VanWoert et al.¹⁵; Zhang et al.¹⁶). In contrast, impervious paved surfaces impede infiltration and exacerbate flood hazards.

Beyond flood hazard mitigation, micro-scale NbS provide multiple (regulatory) ecosystem services that, when realised through implementation, generate tangible (human) co-benefits (Table 1). These perceived benefits strongly influence public willingness to implement NbS, especially in the Global South¹⁷. Specifically, greenery can improve air quality by removing pollutants such as ozone, nitrogen dioxide and particulate matter, especially through trees, green roofs and façades^18,19. NbS like hedges, green façades and shade trees can also contribute to noise reduction, with studies showing up to 15% sound attenuation^20,21. These regulating services help to improve human health, including mental health, reducing depression and anxiety²², as well as lower cardiovascular diseases²³. In terms of provisioning services, food and herbs (and income) can be sourced from vertical gardens, potted plants and tree crops, potentially contributing to urban subsistence or commercial farming^24,25,26. For cultural services, green walls, lawns and shade trees offer high aesthetic and recreational value^18,27. Some NbS provide intangible benefits like spiritual well-being, therapeutic effects and a sense of place identity²⁸. These multiplicities of benefits are key for a region like sub-Saharan Africa (SSA), which faces converging pressures of informality, green space depletion and hazard exposure.

Table 1 Mapping of NbS measures to their associated co-benefits

Despite policy recognition for harnessing these benefits, NbS implementation in SSA faces substantial barriers. A major reason is the rapid rate of urbanization, which outpaces planning regimes. A city like Dar es Salaam, Tanzania, expanded built-up areas by 172% between 1998 and 2018, largely through informal developments that depleted green space²⁹. Similar trends occurred in Harare, Zimbabwe, where built-up areas grew by 92% from 1986 to 2016³⁰. In the Greater Kumasi Metropolitan Area (GKMA) in Ghana also, urban land increased by 78% over the same period and green and water-related ecosystems declined by 54% and 59%, respectively^31,32. In terms of governance, fragmented planning processes, weak institutions and socio-cultural factors (e.g., negative perceptions and limited integration of local knowledge) create barriers to NbS uptake^33,34. Moreover, regional and national policy implementation mechanisms often fail to reach local contexts because of funding constraints^35,36. Also, international funding streams (e.g., Global Environment Facility, the Green Climate Fund and the African Development Bank (AfDB)’s Africa Climate Change Fund) exist to support climate-resilient infrastructure and NbS in developing countries. However, inflows remain inadequate and resources that are mobilised frequently favour large, high-profile projects in relatively resilient areas over local, small-scale solutions in vulnerable urban settings (e.g., World Bank^37,38). As a result, these imbalances deepen urban vulnerabilities, with the consequences most severely experienced at the neighbourhood and household levels^39,40.

Hence, in this paper, we argue for greater attention to micro-scale NbS, especially through private actions (as a complement to the state’s efforts), which can deliver multiple, urgently needed benefits in rapidly urbanising SSA cities beyond hazard reduction⁴¹. First, because they are embedded directly within neighbourhoods and households, micro-scale measures provide highly localised benefits where vulnerabilities are most acute, while also offering cumulative impacts at scale if widely adopted⁴². Yet, micro-scale measures account for only 23% of reported NbS in SSA (Enu et al.⁴³), underscoring both the limited uptake and the vast opportunity for expansion. Second, these interventions expand equitable access to multifunctional green spaces in settings where public greenery is scarce, decentralising NbS uptake and enabling non-state actors—particularly citizens and communities—to participate actively. This reduces the burden on municipal governments, fosters environmental stewardship and reflects the reality that (urban) land is controlled by diverse actors beyond the state that primarily regulates (Fakirova et al.⁴⁴). Third, micro-scale NbS can enhance ecological connectivity across fragmented landscapes and advance “green–grey integration,” whereby NbS are designed as core elements of urban infrastructure rather than ornamental add-ons⁴⁵. Compared with large-scale projects, they are often easier to implement, require lower upfront costs and can be tailored to diverse neighbourhood conditions.

In practice, scattered initiatives in Kenya⁴⁶, South Africa⁴⁷, Tanzania⁴⁸ and Uganda⁴⁹ already demonstrate the promise of (community-driven) micro-scale NbS for stormwater management, biodiversity restoration, flood mitigation and food security. But their reliance on external support and limited scalability reveal systemic barriers that remain insufficiently captured in the academic literature. While there is emerging research on this topic in SSA⁵⁰, they rarely focused on the micro-scale. Nonetheless, Thorn et al.⁵¹ advanced the field by proposing an eight-domain framework, including financial, institutional, spatial and socio-cultural dimensions, but the relative importance and interdependencies among these domains remain poorly understood, despite evidence that interdisciplinary approaches are critical for overcoming them⁵². This gap is particularly significant because the effectiveness of NbS depends on coherent action across interlinked stages of planning, implementation (with maintenance and stewardship) and iterative cycles of innovation, reflection and adaptive learning^53,54,55. Understanding how enabling and constraining factors interact across these stages (rather than addressing them in isolation) can reveal strategic leverage points for prioritization, resource allocation and institutional coordination⁵⁶.

The GKMA in Ghana offers a representative case for examining these issues related to the constraining and enabling context that promotes micro-scale NbS in SSA. Like many rapidly urbanising cities in the region (e.g., Dar es Salaam, Nairobi and Kinshasa), GKMA faces concurrent pressures of informal settlement growth, weak enforcement of planning regulations and heightened climate risks such as flooding and heat stress⁵⁷. These dynamics have driven severe green space loss, extending even to micro spaces as 53% of private homeowners have sealed their courtyards with impervious materials (e.g., concrete, tiles)⁵⁸. This trend occurs in both affluent and low-income neighbourhoods (Fig. 1), emphasizing the urgency of reintroducing greenery at the micro-scale based on neighbourhood priorities. In parallel, opportunities for integrating NbS exist because surveys indicate that GKMA residents already favour creating lawns in residential areas among their preferred measures for flood risk reduction⁵⁹. This provides an entry point for socially acceptable nature-based interventions. Furthermore, national policy instruments in Ghana, such as the Ghana Building Code⁶⁰, include provisions for integrating greenery into building designs (table S1).

Fig. 1: Extent and spatial manifestation of sealed residential landscapes and potential NbS transitions in the Greater Kumasi Metropolitan Area, Ghana.

a Ground-level views of residential plots characterised by extensive tiling and concrete surfacing. b Aerial imageryshowing the distribution of impervious residential surfaces across the study area (Google Earth image; imagery © Airbus 2024, © Google. This figure is not covered by the Creative Commons licence of this article). c Schematic illustrations of residential plot conditions, contrasting the current sealed state with probable and desired transitions toward reduced impervious surfaces through NbS integration.

Implementing micro-scale NbS (in GKMA and similar contexts) may involve reducing or removing sealed surfaces; establishing lawns, tree crops, hedges and permeable pavements; and/or introducing green building features such as façades, walls and roofs. Because built infrastructures are generally viewed as symbols of progress in many areas and greeneries are seen as underutilised land, micro-scale NbS implementation may be complex to advance⁶¹. Nevertheless, since residents value NbS co-benefits but have limited knowledge of the concept⁵⁹, aligning NbS with preferred co-benefits can enhance social acceptance and promote uptake.

With this background, we aimed to answer the question of how micro-scale NbS can be increased, leveraging citizens’ preferred co-benefits for socially acceptable NbS, especially in rapidly urbanising cities where green space depletion is most entrenched. While our focus was on micro-scale NbS, which are purposefully planned and implemented, we embraced all forms of greening (formal and informal) to maximize opportunities for expanding urban nature, thereby enhancing ecosystem functions and benefits that support human well-being. Specifically, we sought to: (1) identify socially acceptable and contextually appropriate NbS measures, with a primary focus on flood risk reduction across different neighbourhoods, by analysing residents’ preferences for diverse NbS co-benefits; (2) investigate the hindering and enabling factors influencing the protection and implementation of micro-scale NbS across key domains (e.g., governance, technical, financial, socio-cultural); and (3) examine the correlations between these factors in order to identify critical leverage points for strengthening NbS uptake. We adopted an explanatory sequential mixed-methods design, combining a citizen survey with a participatory stakeholders workshop and supplementary interviews to engage actors who were unable to attend. Survey data were analysed using descriptive, correspondence and correlation analyses, followed by thematic analysis of the workshop and interview discussions to contextualise and deepen the quantitative results. The remainder of this paper is structured as follows: Section 2 presents the results; Section 3 discusses the findings in the broader context of differentiated pathways to urban resilience through nature in SSA and proposes a strategic framework for micro-scale NbS implementation; and Section 4 details the methodological framework that guided the research.

Results

Most preferred NbS co-benefits and appropriate measures

The citizen survey was administered to 622 respondents across low-, middle- and high-income neighbourhoods in the GKMA. Generally, cooling homes (n = 412), aesthetics (beautify homes) (n = 411), air purification (n = 362) and shade (n = 338) emerged as the most preferred co-benefits of NbS. Access to nature (n = 42) and noise reduction (n = 35) were least selected (Fig. 2).

Fig. 2: Preferred NbS co-benefits across different neighbourhoods.

a Percentage of residents selecting the co-benefit(s) in each neighbourhood. b Correspondence analysis plot showing relationships between neighbourhood income levels and preferred NbS co-benefits.

In terms of the distinct clustering of preferences, low-income neighbourhoods closely associated with co-benefits related to water storage capacity, shade and wind protection. Middle-income areas were positioned toward provisioning (e.g. food provision) and regulating ecosystem services (e.g., air purification and cooling homes) with income generation. High-income neighbourhoods grouped around cultural and health-related co-benefits, including recreation, herbs and health improvement.

Using these preferences and the evidence-based mapping of NbS co-benefits (Table 1), shade trees and tree crops appear suitable for all neighbourhoods (Fig. 3). While several measures, including green façades, roofs and walls, seemed suitable for high- and middle-income neighbourhoods, several others were neighbourhood specific, including hedges (low-income) and lawns (high-income).

Fig. 3: Possible NbS measures to implement in different neighbourhoods based on their most preferred co-benefits.

NB: Co-benefits and the NbS that provide them are drawn from Table 1.

Hindering and enabling factors to implementing NbS at the micro-scale

To structure the emerging factors identified in the GKMA case study, we applied the eight-factor NbS adoption framework proposed by Thorn et al.⁵¹, which are (1) climate change; (2) complementarity and integration; (3) design, performance and maintenance; (4) ecosystem services and disservices; (5) financial; (6) land use change and space; (7) legal and institutional; and (8) socio-cultural values, traditions and perceptions.

Survey results

Overall, financial, institutional and socio-cultural constraints emerged as the most dominant barriers to micro-scale NbS adoption across the GKMA. The most significant barrier was financial constraints (37%), cutting across all neighbourhoods but most acute among low-income households, who face high costs of establishing and maintaining greens compared to sealing their compounds. Legal and institutional challenges (14%) and socio-cultural values (12%) followed (Fig. 4).

Fig. 4: Reported hindering and enabling factors for implementing NbS at the micro-scale in GKMA.

a Factors aggregated under themes based on residents in each neighbourhood selecting factors. b Details of reported hindering and enabling factors. NB: Percentages represent the proportion of total mentions of each barrier or enabler theme within each income group. Because respondents could list several factors, totals sum to 100% separately for barriers and for enablers in each group. The factors are also organised based on how enablers directly relate to and address specific barriers.

Neighbourhood-specific patterns were distinct. Financial challenges and land use and spatial constraints appeared the most significant barriers for the low-income through shrinking plot sizes, high densities and limited public green space, compounded by litigation and tenure insecurity. For middle-income neighbourhoods, the primary barriers were related to climate change (water stress), ecosystem disservices and issues related to design, performance and maintenance, especially due to a lack of experts. In high-income areas, the main barriers were related to legal and institutional factors, such as institutional weaknesses and a policy bias toward grey infrastructure. The correspondence analysis (Fig. 5a) reinforced these patterns, with dimension 1 (84.7%) distinguishing between economic–spatial barriers such as land use, space constraints and financial limitations dominant in low-income neighbourhoods, and institutional–cultural barriers (e.g., legal frameworks, socio-cultural perceptions) prevalent in high-income contexts. Dimension 2 (15.3%) reflected smaller, secondary variations tied to climate-related and ecosystem constraints observed primarily in middle-income neighbourhoods.

Fig. 5: Correspondence analysis plot of reported.

a hindering factors and b enabling factors.

Conversely, key enablers identified in the survey clustered around financial incentives (29%); enhancements in design, performance and maintenance (16%); improvements in legal frameworks and socio-cultural awareness. Across neighbourhoods, financial support and institutional improvements dominated in low-income areas; design, maintenance capacity and awareness-raising around socio-cultural values were most prominent in middle-income areas; while in high-income neighbourhoods, complementarity and integration among actors and institutions emerged as the most significant enabling factor (Fig. 5b). Factors related to ecosystem services, land use and climate change appeared peripheral in both survey responses and spatial associations.

Stakeholder perspectives

Stakeholder discussions reinforced and deepened the quantitative trends. Financial limitations were reiterated as the most significant barrier, both for homeowners (e.g., struggling with installing and maintaining greens, including the cost of tools and implements) and local authorities (e.g., the Department of Parks and Gardens, established in 1961 to coordinate urban greening, often cannot carry out its functions effectively due to delays in statutory payments like the District Assembly Common Fund). Proposed enablers included a residential greening fund, corporate social responsibility (CSR)-supported grants for neighbourhood landscaping, given that most Ghanaian companies currently prioritise social causes like health and education, and subsidies or tax rebates on green materials and seedlings.

Stakeholders also highlighted socio-cultural resistance, especially a prevailing perception that sealed compounds are more modern and prestigious than vegetated ones. The consensus was that behavioural change is as critical as financial support. Suggested actions included community sensitisation, campaigns and utilising various communication channels (e.g., door-to-door visits, media engagements through radio, television and social media and focus group discussions) with the Department of Parks and Gardens to reposition greenery as a modern, multifunctional and sustainable components of urban living. In addition, several participants emphasised addressing capacity gaps by equipping public officials, particularly local government officers, with community engagement and sensitisation skills to carry out such work more effectively.

Land use and spatial issues reportedly manifest through limited space for greening due to the reduction in plot sizes sold over time (or high density). A stakeholder indicated: “In the early 1990s, the plot you got for the building was 100x100m, but nowadays you can get three-quarters or even half of that—it could be 70x70m or 80x90m—so by the time you finish building your house, you will be left with a very small space. So, the person might not think of doing lawn because they might need space for car parking” [Estate Developer 3]. Other experts pointed out issues with disputes over land ownership, including the sale of the same land to multiple people, land grabbing and encroachment. Litigation issues can linger for years, often bringing construction to a halt or even leading to demolition. Such disputes divert residents’ limited resources and attention and reduce the willingness or capacity to invest in long-term measures like NbS. Others include environmental degradation by depletion of existing greens and improper waste disposal. Stakeholders urged reforms in land-use planning and plot optimisation to integrate NbS from design stage.

For climate change, the main hindering factor was limited water for irrigation (meteorological drought). Stakeholders advocated for rainwater harvesting and climate-resilient building practices, which could be embedded in building codes.

Ecosystem disservices, as reported by stakeholders, affect residents, particularly children, through pests (e.g., mosquitoes, millipedes, red ants, mice), reptiles (e.g., frogs, lizards, snakes) and wildlife (e.g., birds and bats) that pose dangers in the form of vector-borne diseases, allergic or toxic bites and stings, contamination of domestic environments and heightened perceptions of fear and insecurity in green spaces. These disservices also compromise the structural integrity of buildings when roots and branches overgrow and weaken foundations or pose physical hazards. Stakeholders further observed that fruit-bearing tree crops, such as mango, guava and pawpaw, can attract trespassers. Strengthening the evidence base on the net benefits of NbS (e.g., green roofs), especially their capacity to mitigate risks and reduce household energy costs, was therefore viewed as an important enabler.

Regarding design, performance and maintenance, the deficit of skilled landscapers and planners was identified as a critical gap. Experts recommended a shift from “water-avoidance” design, which excludes water through impermeable barriers, to “water-entry” approaches that manage water constructively within compounds (e.g., adaptive landscaping with hydrophytic vegetation). However, they acknowledged that finding professionals skilled in this concept could be challenging, as existing landscaping companies often lack the technical and economic capacity to meet clients’ needs. Stakeholders proposed training programmes for both residents and public officials, possibly supported by non-profits, to build local capacity for design and maintenance of micro-scale NbS.

Finally, legal and institutional constraints were described as deeply systemic. Weak planning oversight, political bias toward grey infrastructure and limited engagement of traditional land authorities, who control nearly 78% of (urban) land, impede NbS uptake. Although nature conservation and restoration have been incorporated into key policies like Ghana’s National Adaptation Plan framework, local governments have yet to operationalise these provisions effectively. One expert noted that building plans without “grey” fence walls are often deemed incomplete by the Physical Planning Departments (within local government administrations), revealing a persistent structural bias. Stakeholders proposed pragmatic remedies, including amending permitting frameworks to mandate NbS considerations in design approvals, introducing disincentives such as higher fees for tree-felling permits and penalties for excessive landscape sealing under Regulation 1(2) of the Environmental Assessment Regulations (1999, LI 1652) and demonstrating government leadership by integrating NbS into public infrastructure. Local governments were also urged to legislate land development practices that actively promote NbS adoption.

Correlations between hindering and enabling factors

The Pearson correlation analysis revealed strong interdependencies between several hindering and enabling factors (Fig. 6). State funding showed a high degree of connectivity, inversely correlating with awareness-raising (r = −0.15 to −0.25, p < 0.05) and collaborative planning (r = −0.20 to −0.30, p < 0.05), suggesting these enablers may be less emphasized in well-funded contexts or function as compensatory mechanisms where state support is limited. More directly, state funding was strongly inversely correlated with financial constraints (r = −0.55 to −0.60, p < 0.01), confirming that fiscal inputs mitigate resource-related barriers. Awareness-raising displayed strong associations showing that communication and education jointly counteract disinterest in NbS. Specifically, it was associated with enhanced capacity building (r = −0.10, p < 0.05) and negatively with apathy toward greens (r = −0.08 to −0.10, p < 0.05). Institutional coordination also emerged as a pivotal enabler, correlating with stakeholder collaboration (r = −0.10, p < 0.05) and integrated planning (r = −0.10, p < 0.05). Lastly, capacity building showed a consistent negative correlation with financial constraints (r = −0.20, p < 0.05), highlighting its role in reducing cost-related barriers to NbS adoption.

Fig. 6: Heatmap showing the strongest correlations between hindering and enabling factors.

(See fig. S1 for details). NB: The figure visualises the Pearson correlation coefficients between the various factors, with values ranging from -1 (strong negative correlation, in red) to 1 (strong positive correlation, in green). The hierarchical clustering groups similar factors together based on their correlation patterns. Factors within the same cluster tend to have stronger correlations with each other and interdependencies).

At the workshop, the stakeholders explored cascading interactions between hindering and enabling factors to identify the enablers that overcome several barriers concurrently. Notably, diversifying funding, capacity building through expert consultation and addressing negative perceptions on NbS (e.g., NbS are costly or less appealing) through awareness-raising campaigns stood out (Fig. 7).

Fig. 7: Concept map showing stakeholders’ mapping of (most significant) cascading interactions between hindering (red) and enabling (green) factors to NbS uptake in the GKMA.

(See table S5).

Overall, the correlation and stakeholder analyses showed partial alignment (table S4), converging strongly on state funding as the primary enabler that alleviates financial constraints (r = −0.58, p < 0.01). Capacity building and awareness-raising also emerged as beneficial, though with weaker correlations. However, several stakeholder-identified pathways, including collaborative planning and communication campaigns, did not correlate significantly, potentially reflecting complex non-linear relationships or insufficient implementation as priorities in practice.

Discussions

In this study, we sought to understand how urban nature, often perceived as underutilised land in SSA⁶¹, can be expanded in micro-spaces by leveraging citizens’ preferred co-benefits to promote socially acceptable NbS in the region. The research was situated within the context of rapid urbanisation characterised by population growth driven by rural–urban migration, extensive informal development⁶², the loss of urban greenery³¹ and escalating exposure to hazards such as floods⁶³. The GKMA in Ghana was selected as a representative case because it exemplifies these dynamics, making the findings transferable to other cities across the Global South facing similar patterns of unregulated expansion and climate vulnerability. Against this backdrop, the discussion first interprets residents’ preferences for NbS co-benefits across socio-economic groups to identify contextually appropriate micro-scale measures that align with neighbourhood priorities and constraints. It then analyses the barriers and enablers shaping NbS and structures them around the interrelated stages of implementation—strategic planning, operational implementation (with maintenance and stewardship) and continuous improvement (innovation and learning)—to capture both the practical and adaptive dimensions of the implementation process.

The high value that respondents placed on NbS co-benefits, despite limited awareness of the concept itself, can be leveraged to promote NbS at the micro-scale. Hence, the communication and policy efforts around NbS should centre around the benefits most meaningful to citizens, such as cooling homes, beautifying surroundings, purifying air and providing shade, rather than as abstract environmental concepts. Preferences were strongly related to socio-economic status, indicating both pressing environmental needs but also broader livelihood conditions. While low- and middle-income neighbourhoods prioritised provisioning and regulating ecosystem services, their motivations differed. Low-income communities emphasised water regulation, shade and wind protection as survival-oriented responses to inadequate infrastructure, a pattern similar to observations in Dar es Salaam’s Msimbazi catchment due to flooding²⁹ and Kampala’s urban agriculture initiatives⁶⁴. Middle-income areas, by contrast, prioritized food provision, air purification and cooling, balancing environmental comfort with opportunities for income generation, similar to observations in Harare³⁰ and Kinshasa²⁶, where urban greenery is valued for as amenity and livelihood resource. The results also indicate that inequalities in accessibility to quality green spaces exist and have health implications. Across income levels, inequalities in green space access result from physical barriers (e.g., distance and spatial exclusion) in low-income areas and social barriers (e.g., concerns over safety, maintenance and exclusivity) in high-income areas, revealing broader evidence that unequal or poor-quality green infrastructure is linked to reduced well-being and health outcomes^27,65. Unsurprisingly, high-income residents prioritised cultural and health-related co-benefits. This mirrors Durban’s Green Corridors initiative, where biodiversity enhancement as well as social and health goals are promoted⁶⁶. These patterns demonstrate that the application of micro-scale NbS in SSA is shaped by immediate socio-economic realities (survival for the low-income, quality of life and income for the middle-income and health and well-being for the affluent), necessitating a nuanced, context-sensitive approach to NbS planning.

Translating residents’ differentiated preferences into implementable micro-scale NbS requires aligning desired co-benefits with the realities of each neighbourhood. The findings reveal that in low-income areas, limited plot sizes, insecure tenure and weak (and short) building structures restrict the feasibility of technically demanding interventions such as green roofs or façades. High upfront and maintenance costs further deter adoption without financial or technical support. Consequently, hedges, shade trees and tree crops emerge as the most suitable and socially and structurally realistic measures (Table 2) since they fit within small compounds, require minimal modification and directly deliver the co-benefits most valued by residents, especially shade and wind protection (Table 1). While more resource-intensive options could provide higher hydrological benefits, the results suggest these will only become viable if long-term subsidies or community maintenance schemes offset the financial and capacity barriers⁶⁷. In middle-income neighbourhoods, residents reported similar ecological aspirations but coupled them with concerns about design quality, maintenance and climate-related constraints. This indicates that their adoption decisions are mediated more by issues of durability and aesthetics than by immediate survival needs. Thus, green façades, shade trees, potted plants and tree crops, which balance aesthetic appeal, air purification and modest income generation (Table 1), are both functionally and perceptually aligned with their priorities. Yet the observation that fruit-bearing species may attract trespassers or pests, or even unintended consequences (e.g., nutrient leaching and pollution from pesticides), highlights the trade-offs between provisioning and potential social disservices, reinforcing that NbS effectiveness is as much social as ecological⁶⁸. Integrating drought-resistant and low-maintenance plants such as mango (Mangifera indica), neem (Azadirachta indica) and cassava (Manihot esculenta), therefore, offers a pragmatic balance between performance and manageability⁶⁹. For high-income areas, spatial constraints were minimal, but persisting institutional and regulatory barriers (lack of supportive policies) constrain implementation. Hence, measures that rely more on citizen self-organisation, like using easily obtainable indigenous species, such as bitter leaf (Vernonia amygdalina), scent leaf (Ocimum gratissimum) and aidan fruit (Tetrapleura tetraptera), can align ecological goals with cultural preferences and reduce dependence on the state. Embedding such locally adapted vegetation supports a decolonised, bottom-up approach that transforms traditional ecological knowledge into a living infrastructure of resilience⁷⁰. Collectively, these findings indicate that tailoring NbS to neighbourhood-specific barriers and resource capacities will be crucial for achieving socially acceptable, equitable and scalable NbS implementation in SSA.

Table 2 NbS measures to prioritise in different neighbourhoods with suggested priorities considering existing barriers

In terms of the most interrelated barriers and enablers (Figs. 6 and 7), which would be central at the strategic planning level, first, financial constraints emerged as the most significant. This mirrors broader SSA trends, where limited fiscal capacity⁶¹ and competing development priorities undermine long-term sustainability planning⁷¹. The results suggest that without targeted financing mechanisms, even strong local interest in NbS co-benefits will remain unrealised. Diversifying funding sources is therefore essential. While international mechanisms (e.g., the AfDB’s Africa Climate Change Fund) provide important opportunities, our findings reinforce critiques that these funds remain insufficient and disproportionately channelled toward large-scale, high-visibility projects in relatively resilient areas (e.g., World Bank^37,38) rather than the small, community-level interventions where vulnerability and adaptation needs are greatest^39,40. Correcting this imbalance will require the creation of explicit micro-scale funding windows within international and regional climate finance and enhanced local capacity to access and manage such funds. The GKMA findings also align with lessons from European cases, like Vienna’s courtyard greening programme⁷² and Berlin’s GründachPLUS initiative⁷³, that show how municipal co-financing can significantly lower adoption barriers at the household level. In SSA cities, establishing local greening funds, subsidising green materials and incentivising public–private partnerships (PPPs) could similarly stimulate uptake. Notably, the stakeholders pointed to CSR as an underused avenue, particularly given the example of South Africa, where a recent rise in corporate social investment to over €600 million in 2022 (nearly five times the 2015 figure)⁷⁴. This finding implies that redirecting even a small fraction of private CSR investments toward urban resilience-building could substantially expand greening capacity while improving corporate reputation and public engagement for such companies. Ultimately, increasing central-to-local funding transfers and improving fiscal predictability will be critical to ensure sustained, locally managed greening efforts capable of reaching vulnerable communities.

Second, the correlation analysis revealed efficient institutional capacity as one of the strongest enablers of NbS uptake. Although Ghana’s policy landscape is relatively progressive (exemplified by policies like the Building Code (2018) and Green Ghana Project (2021) (table S1)), our results show that local governments often lack the autonomy, resources and coordination mechanisms necessary to operationalise these frameworks effectively. This policy–practice gap reflects the wider governance fragmentation observed across SSA, where institutional overlap and weak enforcement undermine implementation despite well-intentioned national strategies³³. The GKMA findings suggest that vertical coordination between national and municipal authorities is particularly critical because, without it, even well-designed policies fail to cascade into actionable, micro-scale interventions. Comparative experiences reinforce this interpretation. Durban’s eThekwini Municipality demonstrates how empowered local governments can mainstream NbS into adaptation planning, as seen in its Transformative Riverine Management Programme, which integrates small-scale wetland restoration, roadside greening and household food gardens within a broader resilience framework⁷⁵. Similarly, Kampala’s urban agriculture ordinances, which formalised household greening through local by-laws, illustrate how institutional reform can legitimise and sustain bottom-up initiatives⁴⁹. These parallels highlight that bridging Ghana’s implementation gap will depend on establishing dedicated institutional champions, similar to Medellín’s Green Corridors Secretariat, to drive accountability and cross-sector collaboration⁷⁶. Embedding adaptive governance mechanisms, including regular stakeholder dialogues and participatory policy reviews, would further align with the study’s evidence that flexibility and learning enhance institutional responsiveness. Such iterative structures ensure that NbS policies evolve alongside changing urban and climatic realities, strengthening their long-term legitimacy and impact⁵².

Thirdly, the results showed that despite widespread recognition of NbS co-benefits, adoption remains constrained by entrenched perceptions of “modernity” equating to paved or built-up compounds, an association reinforced by aesthetic norms and social aspirations⁷⁷. This suggests that urban residents often view greening as secondary to development, which helps explain the low prevalence of household-level NbS even where awareness of environmental issues exists. Addressing this requires reframing NbS as visible symbols of urban progress and liveability, and not as environmental add-ons. The survey correlations revealed that awareness-raising had multiplier effects, showing inverse associations with state funding and capacity building, suggesting compensatory mechanisms, yet reducing apathy and educational gaps among residents by shifting perceptions. However, behavioural change is gradual and context-dependent⁷⁸. In East Africa, urban agriculture is culturally embedded⁷⁹, thus, acceptance of NbS may be higher compared to West Africa, where the monetisation of urban land limits ecological reinterpretation⁸⁰. These regional contrasts help explain the relatively low self-initiated greening observed in the GKMA, despite favourable climatic conditions³¹. Yet, as rising heat stress and extreme weather intensify across West Africa⁶³, direct experience of these impacts could deepen public awareness of the need for shade, cooling and comfort and foster greater receptivity to NbS. In this context, government buildings and public spaces could play a demonstrative role to show that greening is integral to modern, resilient urban life to mirror good examples in other regions to integrate green façades and roofs across public infrastructure⁸¹.

Fourthly, land use and spatial constraints emerged as significant limitations in the GKMA, particularly in low-income areas, reflecting the steady reduction in plot sizes driven by rapid urban growth and escalating land demand in SSA^33,82. This finding underscores a critical spatial tension revealed by the study, that while some residents may value micro-scale NbS for their co-benefits, the physical form of the city might increasingly restrict their feasibility. Yet, as stakeholders noted, even smaller plots—around 70 × 70 m in the GKMA, with estimated floor area ratios of roughly 0.5–1.0⁸³—can still accommodate lawns or small-scale crop gardens when space is efficiently designed. Comparable examples, such as homeowners cultivating productive gardens on plots as compact as 30 × 30 m in other regions⁸⁴, reinforce that the constraint lies less in the absolute lack of space and more in the absence of design knowledge, institutional guidance or motivation. This interpretation highlights that spatial limitation may be more socio-technical than physical. Therefore, addressing this challenge requires not only improved spatial planning but also the strengthening of technical expertise and professionalisation within the landscape architecture sector. Doing so would enable residents to better translate their preferences into tangible greening actions.

Lastly, complementarity and integration enablers are essential for fostering the interdisciplinarity and shared responsibility needed to scale micro-scale NbS successfully. Although these enablers were less frequently mentioned in the survey, the correlation analysis identified their critical indirect role in improving coordination among actors as well as strengthening collaboration and implementation outcomes. This suggests that fragmentation, more than the absence of knowledge or policy, often limits NbS uptake in SSA. Similar coordination weaknesses have been documented in Chinese⁸⁵ and European cities³⁴, confirming that interdisciplinarity rarely emerges spontaneously, but requires deliberate institutional design. For SSA, these implications are particularly acute since overlapping mandates and poor communication between state agencies, traditional authorities and private actors already hinder synergy and resource alignment⁸⁶. Hence, the results indicate the need for a more integrated, multi-level governance approach where municipal planning forums function as negotiation spaces for joint problem-solving. Clearly defining institutional roles and strengthening stakeholder representation can directly address the observed implementation gaps. Moreover, adopting a decolonised planning approach that engages local voices and community knowledge can align formal policy intentions with lived urban realities⁸⁷ and advance the kind of “scaling deep” co-production of NbS that builds social legitimacy, equity and lasting local stewardship⁸⁸.

The results indicate that translating enabling conditions into effective on-ground action remains constrained by persistent technical and structural limitations, highlighting the gap between awareness of NbS and their practical realization. The strong correlation between barriers linked to design, performance and maintenance underscores that the operational phase of NbS is shaped less by attitudinal resistance than by systemic capacity deficits. In the GKMA, this gap reflects the limited expertise in landscape and architectural design following the decline of coordinated, state-led housing programs that historically integrated green spaces as standard design elements. They have, since the late 1980s, been replaced by fragmented, self-built housing that use limited professional planning and design input⁸⁹. Consequently, even if residents expressed willingness to adopt NbS, their implementation may be superficial because technical guidance and financing mechanisms may be absent. Financial constraints compound these technical gaps because, although mortgage systems nominally cover up to 80% of building costs, stringent qualification criteria and high interest rates effectively exclude most urban residents⁹⁰. This finding explains why residents prioritise structural completion over landscaping and reveals a rational sequencing of needs rather than a disinterest in greenery. Importantly, the pattern highlights a missed opportunity to mainstream greening during the construction phase, which could create thousands of jobs in Ghana’s emerging landscape design and management sector. With an estimated 35,000–40,000 new housing units built each year, embedding NbS requirements into building codes and local planning regulations (supported by fiscal incentives such as tax rebates or subsidies) would stimulate green employment and also integrate sustainability into urban growth from the outset. The data further reveal that concerns over maintenance and ecosystem disservices (e.g., mosquitoes, snakes, invasive roots) are among the most frequently cited deterrents, particularly in low- and middle-income areas^51,91. This signals not only resource limitations but also a deficit in structured stewardship frameworks and local technical training, suggesting that NbS adoption depends on continuous aftercare rather than once-off installations^54,55. Moreover, respondents’ emphasis on water scarcity highlights the need to integrate climate-smart measures, such as drought-tolerant species and rainwater harvesting, into micro-scale greening initiatives. Overall, the results suggest that operationalising NbS in SSA depends greatly on building routine technical capacity and adaptive maintenance systems that sustain greenery under limited resources and changing climatic conditions.

The correlation analysis revealed that innovation and continuous learning are key enabling factors for micro-scale NbS, highlighting the need for adaptive experimentation to overcome entrenched barriers. This finding shows that the long-term success of NbS in the GKMA also depends on the capacity of urban institutions and communities to learn from experience; to test, adapt and improve interventions through iterative feedback. Stakeholders in this study emphasised that uncertainty about the performance, cost and maintenance of NbS remains a major deterrent, just like in Europe⁹², and suggested that establishing pilot initiatives and community or household demonstration projects as “learning laboratories” can generate locally relevant evidence on effectiveness and disservices. However, such innovation should not be understood solely as technical experimentation but as a relational and social learning process, where co-production, dialogue and reflexivity allow innovation to emerge from everyday interactions and lived experience⁸⁸. This framing is particularly relevant for SSA cities, where informality and socio-cultural diversity make innovation a process rooted in trust, shared meaning and ongoing negotiation among actors and not the linear transfer of knowledge. Lessons from the SSA Challenge Program⁹³ and Integrated Agricultural Research for Development⁹⁴ platforms show that when learning systems institutionalise these relational dimensions, they embed adaptive capacity and accelerate innovation. Conversely, experiences from failed policy innovation labs and urban water projects across SSA show that without feedback mechanisms and reflexive governance, interventions stagnate or collapse under bureaucratic rigidity and resource constraints⁹⁵. Integrating “transformative unlearning” to discard ineffective practices alongside co-creation with residents and the use of traditional ecological knowledge can strengthen local ownership, cultural relevance and institutional responsiveness^54,96. Over time, embedding such iterative and relational learning frameworks will enable micro-scale NbS to evolve from fragmented projects into adaptive, socially rooted governance systems capable of responding dynamically to changing socio-ecological realities in GKMA and similar SSA cities.

Conclusion

While the proposed framework (Fig. 8) provides a clear roadmap for advancing micro-scale NbS, the findings show that widespread adoption will be gradual and complex, shaped by entrenched socio-economic, legal and institutional barriers. Achieving meaningful impact will require strategies that are deeply embedded in local realities and adaptive to diverse neighbourhood contexts. All the constraining and enabling factors are crosscutting across neighbourhoods, but prominence varies by context. In low-income areas, progress hinges on pragmatic, low-cost interventions supported by micro-finance schemes; in middle-income areas, on improving design quality, maintenance capacity and technical skills; and in high-income areas, on enhancing institutional coherence and fostering collaborative, innovation-driven governance (Fig. 9). Across all neighbourhoods, creating diversified and predictable funding streams, such as through municipal co-financing, CSR investment and climate adaptation funds, will be essential to scale adoption equitably. Equally important is reframing NbS as symbols of modernity and resilience through demonstration projects and awareness campaigns that make their benefits tangible. Institutional reforms must clarify roles, strengthen coordination and embed iterative learning mechanisms that enable continuous improvement and social legitimacy. Integrating traditional ecological knowledge and fostering co-production among residents, experts and policymakers will ensure micro-scale NbS evolve as living, context-sensitive and feasible infrastructures. Ultimately, scaling NbS in the GKMA and similar SSA cities depends on combining financial innovation, social equity and adaptive governance to transform fragmented urban spaces into resilient, inclusive and self-sustaining ecosystems of everyday greening. This will help to advance urban sustainability and climate-resilient development across comparable regions.

Fig. 8: Conceptual framework and design considerations for implementing micro-scale NbS in sub-Saharan Africa.

a Concentric framework showing key factors across stages of NbS implementation (strategic planning, operational implementation (including maintenance and stewardship) and continuous improvement (innovation and learning)). b Illustrative configurations of prioritised NbS across neighbourhood types (low-, middle-, high-income), highlighting differences in spatial integration and implementation feasibility. The figure illustrates potential NbS integration and does not prescribe architectural design. (Source: authors).

Fig. 9: Synthesis of pathways linking citizen preferences to micro-scale NbS uptake.

The figure links prevailing sealed residential conditions with enabling mechanisms and resulting patterns of NbS implementation. The central block summarises key governance and implementation levers that translate co-benefit preferences into action. Directional arrows indicate shifts toward alternative development trajectories, illustrated by probable and desired states with progressively reduced impervious surfaces and increased NbS integration.

Methods

Description of case study city: Greater Kumasi Metropolitan Area, Ghana

The GKMA typifies the contemporary urbanisation processes in SSA. Similar to cities such as Dar es Salaam, Harare, Nairobi and Kinshasa, it represents a rapidly expanding metropolitan area where demographic, spatial and climatic pressures converge. These pressures are shaped by planning weaknesses and competing socio-cultural preferences for grey rather than nature-based infrastructure and make GKMA an ideal case for studying the barriers and enablers of micro-scale NbS adoption, both as a distinctive Ghanaian case and as a microcosm of broader SSA urban realities.

GKMA’s population increased from about 500,000 residents in 1984 to about 3.5 million in 2021⁹⁷, with an annual growth rate of nearly 5% mainly through rural-urban drift (54% of inhabitants are (im)migrants) and a high birth rate⁹⁸. The GKMA is located in Ghana’s Ashanti Region, on a low-lying basin intersected by the Owabi and Subin river catchments, whose geomorphology means that flood vulnerability amplifies when green spaces are converted or sealed. The urban fabric is characterised by a complex land-tenure regime, where over 78% of land is under customary ownership controlled by traditional authorities. This pluralistic and largely non-state land governance system complicates spatial planning and law enforcement, which is a common trend across many parts of SSA⁸⁶.

Historically, GKMA (then Kumasi)’s first urban plan in 1945 was modelled after Ebenezer Howard’s Garden City concept, which designated extensive green belts, open spaces and buffer zones for recreation and flood control⁹⁹. These provisions addressed green infrastructure primarily at the macro-scale, complemented by household-level greening practices at the meso- and micro-scales, where residents cultivated food gardens, maintained remnant vegetation and planted ornamentals for social gatherings and relaxation¹⁰⁰. However, these practices have progressively diminished. Between 1991 and 2019, more than 80% of urban green spaces were lost to residential and commercial development (Fig. 10)¹⁰¹. In recent times, courtyard sealing and the proliferation of impervious surfaces within private compounds have further accelerated runoff, inhibited infiltration and reduced local microclimatic regulation (Fig. 1).

Fig. 10: Land use distribution and sampled neighbourhoods in the Greater Kumasi Metropolitan Area.

The main map shows land use classes alongside administrative boundaries and river networks. Sampled neighbourhoods are indicated by point markers.

The physical and climatic context of GKMA intensifies these risks. The city lies in a tropical wet–dry zone (Aw in Köppen climate classification) with a bimodal rainfall regime (mean annual rainfall of 1400 mm) and an average temperature of 26–27 °C. Rapid urban expansion, combined with vegetation loss, has elevated ambient temperatures by more than 1.5 °C since the 1980s and increased the frequency of extreme heat days. Parallel to this, approximately half of the city’s area is now at moderate-to-high flood risk¹⁰². These climatic pressures mirror those of other tropical SSA cities such as Lagos, Nairobi and Dar es Salaam, and position GKMA as a representative climate-sensitive urban ecosystem where nature-based interventions can yield immediate resilience benefits.

In terms of the socio-institutional context, GKMA operates under a fragmented planning and governance structure, with overlapping mandates among local assemblies, sector departments and traditional authorities^31,32. Urban development remains largely reactive, characterised by post-flood infrastructural responses and limited proactive planning⁸². Despite national programmes such as the Green Ghana Project (since 2021), greening efforts remain sporadic and focused on macro-scale tree-planting rather than integrated household or neighbourhood interventions⁵⁹. Meanwhile, heavy reliance on hard drainage infrastructure as a flood-control measure reflects the dominance of grey planning paradigms. Insights from GKMA therefore, extend beyond the local context and offer transferable lessons for building sustainable, climate-resilient cities in SSA.

Mixed methods approach

We used a mixed methods approach with an explanatory sequential design to capture the multifaceted social, institutional and environmental dynamics influencing the implementation of micro-scale NbS in the GKMA (Fig. 11). Quantitative data were first collected through a household survey of residents, followed by qualitative data collection from a multi-stakeholder workshop and supplementary expert interviews. The sequential design allowed the qualitative phase to elaborate on and contextualise statistical patterns emerging from the survey to ensure a comprehensive and grounded understanding of both the barriers and enablers to NbS adoption in GKMA.

Fig. 11: Research design and workfl ow for assessing micro-scale NbS implementation.

The figure outlines sequential phases of the study from August 2022 to August 2023. Arrows indicate the flow of information across methods, culminating in triangulation and synthesis to generate insights for policy and practice.

The survey design and thematic scope were informed by prior studies examining NbS co-benefits and adoption determinants^34,51,85. The semi-structured questionnaire combined closed-ended questions, which elicited residents’ preferences among 19 predefined NbS co-benefits relevant to urban greening priorities in GKMA⁷¹ and SSA (Enu et al.⁴³; Harrison et al.¹⁰³) and open-ended questions, which allowed respondents to describe, in their own words, the hindering and enabling factors to micro-scale NbS implementation. This design captured both quantifiable patterns and nuanced social or behavioural insights, facilitating triangulation between numerical trends and lived experiences. Findings from the citizen survey directly informed the design of the stakeholder workshop to ensure continuity between the two data collection phases. The workshop provided an opportunity for stakeholders from government, academia, the private sector and non-profit organisations to critically examine and expand upon the survey results. Through group discussions and plenary sessions, participants interpreted the quantitative findings in light of their professional and institutional experiences.

Identifying preferred co-benefits and hindering and enabling factors

Six enumerators were trained for the data collection exercise on December 28th and 31st, 2022. Enumerators received additional training to standardise the interpretation and explanation of each question to minimise researcher bias and improve response consistency.

Neighbourhoods were first purposively selected to represent contrasting socio-economic and environmental conditions typical of GKMA and other rapidly urbanising SSA cities. Selection was guided by prior studies^82,104 and consultation with officers of the Kumasi Metropolitan Assembly. The final sites—Tafo Nhyiaeso (low-income, high density), Atonsu-Ahinsan and Ayeduase/KNUST/Kentinkrono enclaves (middle-income, moderate density) and Danyame/Ridge (high-income, low density)—capture spatial and social diversity in income, density and exposure to (flood) hazards¹⁰⁵.

Second, households were selected using a systematic random sampling approach, targeting every third dwelling along main access routes and alternating between both sides of the street. In houses with multiple households, one was randomly selected. The household head was prioritised as respondent; in their absence, a spouse or adult (≥ 18 years) was interviewed. Each interview lasted 30–40 min and was conducted in English or, where necessary, explained in the local language, Twi, to ensure comprehension and inclusivity.

The sample size was calculated following Tshuma et al.¹⁰⁶ with the following formulas:

$${\rm{x}}=\frac{{\mathrm{Zc}}^{2}{\rm{r}}(100-{\rm{r}})}{10000}$$

(1)

$${\rm{n}}=\frac{{N}_{x}}{\left({\rm{N}}-1\right){E}^{2}+x}$$

(2)

$${\rm{E}}=\sqrt{\frac{\left({\rm{N}}-{\rm{n}}\right){\rm{x}}}{{\rm{n}}\left({\rm{N}}-1\right)}}$$

(3)

where,

x is the required sample size,

Z is the Z-quantile at 95% confidence level (1.96),

C is the proportion of the population of interest,

r is the expected response rate in the population,

n represents the required sample size,

N is the total population size, and.

E represents the margin of error.

The survey was completed by 622 respondents: 23% from low-income neighbourhoods, 57% from middle-income neighbourhoods and 20% from high-income neighbourhoods (table S2). To analyse these responses, correspondence analysis¹⁰⁷ was applied using R v4.3.2 to visualise associations between neighbourhoods and NbS preferences or perceived barriers and enablers. Qualitative responses from open text entries were subjected to deductive thematic coding using the eight-factor framework of NbS adoption proposed by Thorn et al.⁵¹. The framework integrates climatic (impacts of climate variability and adaptive responses), institutional and legal (governance structures, regulations and enforcement), financial (access to and reliability of funding), design and technical (availability of standards, technology and expertise), ecological (ecosystem services and disservices affecting human well-being), spatial (land demand and density constraints), complementarity and integration (coordination and citizen engagement) and socio-cultural (attitudes, norms and knowledge shaping acceptance) dimensions, providing a structured lens for comparing neighbourhood-specific barriers and enablers. Each response was coded into the appropriate domain(s) to facilitate cross-case and correlation analyses¹⁰⁸.

Stakeholders’ workshop and qualitative data integration

The stakeholders’ workshop took place on 15 March 2023. Using a purposive peer referral sampling approach, participating stakeholders were selected to identify the relevant experts in urban planning, the built environment and disaster management sectors from the public, private and non-profit sectors. The selection process began with key contacts at the Kumasi Metropolitan Assembly (Development Planning Department) and academics (mostly from Kwame Nkrumah University of Science and Technology), who then referred other relevant professionals who were well-versed on the topic.

Data from the workshop discussions focusing on the hindering and enabling factors to NbS implementation at the micro-scale were harvested into notepads and complemented with the minutes, notes, photos and observations from the five workshop facilitators. The plenary sessions were audio-recorded. Although some stakeholders from the private sector were absent, their views were collected through mop-up interviews (table S4) conducted via Zoom between 19 March and 20 April 2023, involving nine experts. These interviews followed the same guiding questions as the workshop to ensure thematic consistency. Analysis by content thematic method was carried out on the qualitative insights from both the workshop and interviews (table S3)¹⁰⁸.

Assessing correlations between hindering and enabling factors

To explore interdependencies among the factors influencing micro-scale NbS implementation, Pearson correlation analysis was conducted on the survey data. This approach measured how strongly pairs of hindering and enabling factors co-varied to reveal whether improvements in one domain could offset constraints in another. Correlation coefficients (r) were computed using the standard formula (4):

$$\frac{\sum \left({{\rm{x}}}_{{\rm{i}}}-\bar{{\rm{x}}}\right)\left({{\rm{y}}}_{{\rm{i}}}-\bar{{\rm{y}}}\right)}{\surd \left[\sum {\left({{\rm{x}}}_{{\rm{i}}}-\bar{{\rm{x}}}\right)}^{2}\sum {\left({{\rm{y}}}_{{\rm{i}}}-\bar{{\rm{y}}}\right)}^{2}\right]}$$

(4)

where,

x_i and y_i are the individual sample points.

x̄ and ȳ are the means of the sample points x and y.

Σ denotes the sum over all sample points.

P-values < 0.05 were considered statistically significant to ensure that observed relationships reflected meaningful dependencies rather than random variation¹⁰⁹.

Complementing this quantitative analysis, stakeholders qualitatively assessed correlations during the workshop through “cascading interaction mapping” in five breakout rooms, with the results presented on return to the plenary.¹¹⁰. This process revealed how specific enablers can generate multiplier effects to address several barriers simultaneously. Results from both analyses were compared to validate patterns and ensure consistency between statistical correlations and expert interpretations, providing a robust understanding of how structural and behavioural factors interact to shape NbS adoption dynamics¹¹¹.

Mixed methods integration

Integrating survey data, workshop discussions, and expert interviews ensured the robustness and reliability of our results. Triangulation was achieved by merging household survey data with insights from stakeholder discussions and expert interviews, allowing patterns in residents’ perceptions to be validated and expanded through institutional perspectives. Verbatim stakeholder quotes were used selectively to illustrate and substantiate statistical trends. Potential biases were mitigated through cross-comparison of datasets to reveal inconsistencies between citizen and expert viewpoints and prevent over-representation of any single perspective. Preliminary qualitative findings were also circulated among participants for validation over three weeks to strengthen the credibility of the interpretations. This integration followed the principle of complementarity¹¹², wherein qualitative data do not merely confirm but extend quantitative insights.

Ethical considerations

All research procedures complied with ethical standards for human subject research. The Data Protection Office of the Technical University of Munich approved the questionnaire on 13 October 2022 (D417). Enumerators underwent ethics training and carried identification and introduction letters to ensure transparency during fieldwork. Participants were informed that the study was conducted solely for scientific purposes and that all responses would be analysed in aggregate form to preserve anonymity. Participation was voluntary and informed consent was obtained from all respondents prior to data collection. For the stakeholder workshop, written consent was also provided before participation and prior to the recording of audiovisual materials. These procedures ensured adherence to principles of confidentiality voluntary participation and informed decision-making throughout all stages of the research.

Study limitations

This study acknowledges several methodological limitations. First, the selection of traditionally planned settlements in GKMA, even though some (e.g., Tafo and Ayeduase) exhibit unregulated growth, may introduce sampling bias, limiting applicability to informal urban areas that constitute a substantial share of SSA’s urban expansion. Future studies could therefore centre on informal settlements to capture a broader spectrum of social and spatial realities influencing NbS adoption. Second, while triangulation between quantitative and qualitative methods strengthened validity, the qualitative phase relied heavily on expert perspectives, which may reflect institutional biases or individual experiences. Incorporating community-based focus groups in future research could broaden inclusivity and capture local ecological knowledge. Third, this study did not quantify the magnitude of benefits from the co-benefits identified (e.g., food supply, income generation or heat mitigation). Further studies could model or empirically measure these benefits and evaluate potential risk-reduction impacts under enhanced NbS implementation. Despite these limitations, the combined quantitative–qualitative design provided a comprehensive and contextually grounded understanding of the barriers and enablers shaping micro-scale NbS adoption in the GKMA and similar SSA cities.