Ohio spiderwort is an eastern North American perennial that blooms from May through July on the arboretum’s intensive green roof. Remembering this as a shady resident of my mother’s garden, I was skeptical of its performance on a green roof.
Spiderwort has adapted to the roof’s sunny, hot and dry growing conditions with aplomb. Its three-petaled blue flowers last only one day, like miniature daylilies. It receives no special care, other than being cut back in mid-summer after its blooms are spent. With adequate moisture, it may provide a second flush of flowers for fall. In garden beds Tradescantia may grow to 3’, but its stature is reduced on the green roof due to less moisture and leaner soil.