This is the first plant functional trait database for Nova Scotia, Canada. The data contained here were collected between 2016 and 2019 from locations around Halifax, Nova Scotia. The species selected for trait collection were chosen based on species inventories taken across Nova Scotian coastal barrens and from green roofs at Saint Mary’s University. The purpose of the coastal barren trait data was to understand community assembly in this understudied ecosystem. The green roof inventory was included as coastal barren species are known to succeed on green roofs in Nova Scotia. The green roof trait data was used to answer questions surrounding coexistence and trait divergence, and community assembly and spatial heterogeneity. In total, this database contains 14,341 trait values from 203 species comprising 130 genera and 53 families. The majority of species are commonly found on coastal barrens (84 species), disturbed sites (48 species), and forests (27 species). Additionally, this database contains trait data for 30 species that have been successfully established (survival for >1 year) on green roofs in Nova Scotia and ruderal species that commonly colonize both green roofs and coastal barens. This database contains 12 plant functional traits: leaf thickness (203 species), leaf area (203 species), specific leaf area (203 species), leaf dry matter content (203 species), plant height (203 species), canopy width (203 species), seed weight (79 species), seed shape (61 species), root radius (22 species), leaf phosphorus content (3 species), leaf nitrogen content (30 species), and leaf carbon content (30 species). The species in this database can be subdivided into 10 growth forms, with the majority of species characterized as forbs (75 species), shrubs (56 species), or graminoids (33 species). See NS Flora Guide for details on data