Seed Germination of Native Mediterranean Species for Establishing Self-Sustaining Urban Meadows Supporting Urban Biodiversity

Urbanization reduces biodiversity and affects plant–insect interactions, creating a need for more functional green spaces. Urban meadows with native species are a promising option, but their use is still limited due to a variety of reasons concerning the utilization framework of suitable plant species. The present study aimed to develop seed germination protocols for 26 native Mediterranean herbaceous species originating from northeastern Greece selected to support the establishment of species-rich and self-sustaining urban meadows. To the above end, seed germination experiments were conducted ex situ under controlled environment conditions using seeds collected from the wild for each species. Seed viability was assessed using the tetrazolium (TTZ) test to determine the maximum germination potential in each case. Freshly collected seeds were stored under ambient conditions for approximately 3 months (after-ripening) prior to germination testing, which was followed by cold stratification as a pretreatment for dormancy release. The results showed high embryo viability in all species and indicated that most taxa exhibited either no dormancy or relatively shallow physiological dormancy. Germination tests revealed that 14 of the 26 species presented high germination percentages in the control treatment, which suggests that after-ripening contributed to dormancy release in a significant portion of the seed lot. However, it remains unclear whether freshly collected seeds require an initial after-ripening period before responding to cold stratification. Furthermore, cold stratification significantly enhanced germination in 12 species confirming its effectiveness as a simple and practical method for dormancy release. In addition to the seed germination results, the selected species present a wide range of functional and esthetic characteristics, including variation in plant height, flowering phenology and flower and leaf color. These traits are important for both ecological performance and visual quality in urban environments. The combination of extended flowering periods and color diversity suggests the potential for continuous floral resource availability, which can support diverse pollinator communities and, indirectly, urban fauna such as insectivorous birds. The results indicate that the studied species are suitable for biodiversity-oriented urban plantings. Their relatively shallow dormancy and ease of propagation, coupled with their functional and aesthetic traits, support their use in the development of resilient and self-sustaining urban meadows.