Astilbe chinesis plumila: Blooms August. This neat dwarf grows less than a foot tall and is one of the most useful of all Astilbes because it blooms in late summer and is relatively tolerant of dry soils. It also creeps by underground stems, making it the best Astilbe for use as a ground cover. The flower spikes are lilac pink with a hint of violet as they open and will liven up the front of the border at a time when good pinks are scarce.