By Kristen Jovanelly and Theresa W. Ong

This Plain Language Summary is published in advance of the paper discussed. Please check back soon for a link to the full paper.

Community gardens are distinctive urban spaces where people from many backgrounds come together to grow food, build community, and spend time with nature. Each gardener brings particular preferences, habits, crops, aesthetics, and ways of caring for a plot. These differences beget difference: one bed may be dense with tomatoes and beans, another edged with flowers, another carefully weeded, and another temporarily overgrown.

Yet community gardens are also places of exchange. Gardeners notice what thrives in a neighbor’s plot, share seeds and seedlings, borrow practical know-how, adapt to shared rules around care, and gradually fold new practices into their own. Over time, these everyday exchanges can create common patterns: similar crops, routines, and spontaneous plants within a single garden, across gardens, neighborhoods, and cities. Our study began with this tension between difference and similarity. Do community gardens retain distinct ecological signatures, or do shared practices and repeated disturbance make their plant communities more alike?

To explore this question, we looked below the surface. Garden soils contain seed banks: living archives of seeds shaped by past planting, weeding, disturbance, compost, surrounding vegetation, and daily rhythms of care. These buried seeds also shape what grows next, influencing which plants return after disturbance, how gardens respond to changing conditions, and whether future growth becomes dominated by a few persistent weeds

We studied soil seed banks in 37 community gardens across eight neighborhoods in Boston, USA. We collected soil from 350 garden plots and grew the samples in a greenhouse for sixteen months to see which plants emerged. Most seedlings were fast-growing, disturbance-tolerant species often described as “weeds.” However, plant abundance, diversity, and composition also varied across plots, gardens, and neighborhoods. Although predictors emerged at all scales, garden-level management mattered strongly. Interestingly, gardens with more observed abandonment or inactivity did not have more germinating “weedy” plants, but lower seed bank abundance and diversity. This challenges a common assumption that visible weediness reflects neglect. Instead, our results suggest that spontaneous plants emerge through relationships among gardening practices, shared rules, disturbance, surrounding green space, and longer-term soil memory.