Urban forests are widely recognised as key nature-based solutions to improve sustainability and resilience of cities. This is particularly the case of southern Europe cities increasingly exposed to heat and drought extremes but also to heavy precipitation, which do affect tree health and survival, and the delivery of ecosystem services. While considerable attention has been given to post-planting management, the success of urban green infrastructure largely depends on the quality (morphological, phytosanitary) of the planting material, which places nurseries at a crucial position within the urban forestry supply chain.

In this context, the present study examines the functioning of the micro scale ornamental nursery at the Instituto Superior de Agronomia (ISA) and its potential for certification, with particular attention to its role in supplying the local market with high-quality trees for urban environments. The certification framework, regulated at the national level, ensures traceability, phytosanitary standards and legal compliance, and can therefore play a decisive role in increasing the reliability of planting material used in urban projects.

The work included the technical assessment of ten woody ornamental species used as mother plants in the Tapada da Ajuda Botanical Park. Mother plants were evaluated in terms of their morphological characteristics, phytosanitary condition, and compliance with certification requirements. At the same time, the nursery’s infrastructure, propagation techniques and management practices were analysed, complemented by a SWOT approach to identify its main strengths, limitations and development opportunities.

The results suggest that most of the evaluated specimens fulfil the criteria required for certification, indicating a solid potential to produce high-quality planting stock. Nevertheless, some constraints were identified, particularly related to infrastructure, available human resources and technology issues, which are common in micro to small scale nursery systems. The study also highlights the relevance of maintaining consistent records, improving phytosanitary monitoring and progressively adopting more sustainable practices, including alternative substrates, more efficient water use and integrated pest management. Promote inventories is also crucial to support certification and optimize propagation.

Overall, this work underscores the importance of connecting nursery production with urban forestry objectives. It shows that plant quality, certification processes and phytosanitary control are not marginal concerns, but central elements to minimize losses of planted material and build more resilient urban forests. Strengthening nursery practices should therefore be seen as a strategic, upstream intervention to support healthier, more adaptable and sustainable urban green infrastructures.