Yellow wild indigo carries spikes of pea-shaped yellow flowers over blue-green foliage in late spring, on a native perennial that forms a rounded, self-supporting mound. Baptisia tinctoria grows 2 to 3 feet tall and wide in full sun to part sun, hardy from Zone 3 through Zone 7.
Bloom fills the gap after the spring bulbs finish and before the summer perennials start. Bees come to the flowers, and the foliage feeds wild indigo duskywing and frosted elfin caterpillars.
Small dark seed pods follow and rattle on the stems into winter. The blue-green foliage stays clean and structural through the whole season, which is not something most perennials manage by August.
Baptisia sends down a deep taproot, so it takes three seasons to reach full size and will not transplant well afterward. Put it where you want it. Once established it is drought-proof, takes moderate salt, and needs no staking or dividing. Deer leave it alone.