Mountain Indigobush

Size, growth and what to expect

No source rates its growth, so our growth estimator uses the fast rate of our indigobush, about 2.75 feet a year while young. It makes a much-branched shrub 3 to 6 feet tall. Its leaves run 5 to 9 inches long, with 11 to 15 broad, widely spaced leaflets.

Dense spikes 4 to 7 inches long, alone or in clusters of two to four at the branch tips, open from May into July. The small flowers are purple with golden anthers. Like other amorphas, it bears pods about a third of an inch long, each with a single seed. The smooth pods ripen light brown in mid to late summer.

It grows wild in the southern Appalachians and the nearby Piedmont, from western North Carolina and eastern Tennessee to northern Georgia and northeastern Alabama. Its home is dry to moderately moist oak woods on ridgetops and slopes, mostly at low elevations around the higher Blue Ridge.

How to grow Mountain Indigobush

Mountain indigobush grows in part shade or sun, in a dry to average soil that drains well, like the rocky oak woods of its home slopes. Set plants 3 feet apart and 3 feet from a wall. At its size it can go within 15 feet of overhead wires.

Saplings ship bare-root or potted. Plant them dormant, in a hole wider than the roots and no deeper. Set the crown at the soil line, put the native soil back in, and keep the mulch clear of the stems. Other amorphas have a hard seed coat that a winter outdoors helps to soften. Sow the seed outdoors in fall, about a quarter inch deep.

Water weekly through the first summer, then only in long droughts. Deep shade stunts amorphas, so give it some sun through the canopy.

Each flower carries both male and female parts, so there are no male and female plants to pair. Like other amorphas, it fixes its own nitrogen, so skip fertilizer.