Spiderwort (Tradescantia ohiensis) is a perennial that can grow as tall as 2-3 feet and spread 1.5 to 3 feet. Showy, dark blue to rose-blue flowers will bloom from May to July. It will tolerate full sun to part shade in dry to medium, well-drained soil. You will get more blooms if planted in full sun and may need to divide the clumps if the plant becomes overcrowded. The flowers only open for a day so trim back the plant in the middle of summer to continue blooming into the fall.