Twilight Sky Aromatic Aster

Twilight Sky is the largest of the aromatic asters, reaching 3 to 4 feet tall and about as wide, which makes it a mid-to-back border plant or a mass planting rather than a border edging. This selection of the native Symphyotrichum oblongifolium grows in full sun to part sun, hardy from Zone 5 through Zone 9. Hundreds of periwinkle to violet-blue daisies with yellow centers open from mid-October into November, which is later than almost anything else that flowers. Asters are a keystone genus, and this species draws unusually large numbers of native bees, including specialists that feed on nothing else. It cuts well too. The foliage is stiff and gray-green, releasing a clean balsam scent when brushed, which is what keeps deer and rabbits away from it. Aromatic asters want lean, well-drained soil and full sun. Rich ground and regular water make them grow soft and flop. If you want it shorter and denser, cut the stems back by a third to a half in early to mid June, before flower buds set. It handles drought, heat, poor soil, and moderate road salt once established.