# Mountain Indigobush (Amorpha glabra) > A smooth-leaved indigobush of Appalachian ridges and slopes, 3 to 6 feet tall, with purple flower spikes and golden anthers in early summer. Also called smooth indigobush, Appalachian indigobush, mountain false indigo. Category: Native Shrubs. Grown from seed by Blue Whale Trees. Web version: https://bluewhaletrees.com/plants/mountain-indigobush/ ![Mountain indigobush (Amorpha glabra) young shrub with widely spaced leaflets on a wooded slope](https://bluewhaletrees.com/img/plants/mountain-indigobush-h1610-800.jpg) *Photo: Sesamehoneytart, CC BY-SA 3.0 ยท [Wikimedia Commons](https://commons.wikimedia.org/wiki/File%3AAmorpha_glabra_Mountain_false_indigo.JPG)* ## Facts - Type: Shrub - Mature height: 3 to 6 ft - USDA hardiness zones: 7 to 8 - Grows wild in: The Appalachians, dry uplands and rocky ground - Native range: Alabama, Georgia, North Carolina, South Carolina and Tennessee - Sun: Part, Full - Soil moisture: Dry, Average - Growth rate: Fast - Traits: Showy flowers, Nitrogen fixing - Sold as: Saplings, Seed Heights and zones are typical ranges for the species in cultivation; local conditions and seed source shift them. ## Availability Not yet priced online. Ask at captain@bluewhaletrees.com or leave an email on the web page to be told when it is listed. ## Notes Mountain indigobush is a shrub of the southern Appalachians, from western North Carolina and eastern Tennessee to northern Georgia and northeastern Alabama, where it grows in dry oak woods on ridgetops and slopes. Its hairless stems and leaves set it apart from our indigobush, whose leaves are slightly to very hairy, and its broad leaflets sit well apart along the leaf. NatureServe ranks it vulnerable in South Carolina. Plant it at the edge of dry oak woods or on a wooded slope, where its purple spikes brighten early summer. ## 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. ## Sources - [Wilbur 1975, A revision of the North American genus Amorpha (Leguminosae-Psoraleae), Rhodora 77(811): 337-409, species 8 on pages 377-381](https://archive.org/details/biostor-138235) - [NatureServe Explorer: Amorpha glabra, Smooth Indigobush](https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.134008/Amorpha_glabra) - [Lady Bird Johnson Wildflower Center: Amorpha glabra, Mountain False Indigo](https://www.wildflower.org/plants/result.php?id_plant=AMGL2) - [Georgia Department of Natural Resources, Georgia Biodiversity Portal: Amorpha herbacea var. floridana, similar species](https://georgiabiodiversity.org/portal/profile?group=plants&es_id=15495) - [Marchin and others 2009, Are rare species less shade tolerant than common species in fire-prone environments? A test with seven Amorpha (Fabaceae) species, Plant Ecology](https://doi.org/10.1007/s11258-009-9614-3) - [USDA NRCS PLANTS Database: Amorpha glabra, AMGL2](https://plants.usda.gov/plant-profile/AMGL2) - [GBIF occurrence search, preserved specimens of Amorpha glabra in the United States](https://www.gbif.org/occurrence/search?taxon_key=7639404&country=US&basis_of_record=PRESERVED_SPECIMEN) - [USDA Forest Service, Woody Plant Seed Manual (2008), Amorpha chapter](https://www.fs.usda.gov/nsl/Wpsm/Amorpha.pdf) ## Read before planting - [Ten planting mistakes that quietly kill trees](https://bluewhaletrees.com/articles/ten-planting-mistakes/index.html.md) - [Transplanting young trees: timing, water and protection](https://bluewhaletrees.com/articles/transplanting-young-trees/index.html.md) - [Protecting young trees from voles, rabbits, deer and squirrels](https://bluewhaletrees.com/articles/protecting-trees-from-animals/index.html.md) - [The habitat around a tree is part of the tree](https://bluewhaletrees.com/articles/habitat-around-a-tree/index.html.md) - [Invasive vines and shrubs are what is killing your woods](https://bluewhaletrees.com/articles/invasive-vines-and-shrubs/index.html.md) - [Native trees and shrubs for butterflies and moths: host plants first, nectar second](https://bluewhaletrees.com/articles/native-trees-for-butterflies-and-moths/index.html.md) ## Related - [Planting-site check](https://bluewhaletrees.com/tools/site-check/index.html.md): for a thrive, struggle or fail verdict on Mountain Indigobush, add ?species=mountain-indigobush with zone (2 to 10), sun (full, part, shade) and moisture (dry, average, wet) to that address, for example ?species=mountain-indigobush&zone=7&sun=part&moisture=average. - [Companion species for Mountain Indigobush](https://bluewhaletrees.com/tools/companions/index.html.md?species=mountain-indigobush): the natives that share its ground and the plants that pair with it in a yard. - [Growth estimator](https://bluewhaletrees.com/tools/growth/index.html.md): how the height and trunk projections are made; the estimate itself runs in the browser at https://bluewhaletrees.com/tools/growth/#species=mountain-indigobush - [Seed sowing planner](https://bluewhaletrees.com/tools/sowing/index.html.md): how Mountain Indigobush is sown, in the chart for every species (treatment, cold days, depth, timing); the dated plan runs in the browser at https://bluewhaletrees.com/tools/sowing/#species=mountain-indigobush - [Pollination planner](https://bluewhaletrees.com/tools/pollination/index.html.md): what Mountain Indigobush needs for a crop and how many to plant, in the table for every species; the planner runs in the browser at https://bluewhaletrees.com/tools/pollination/#plants=mountain-indigobush:1 - [Bloom and fruit calendar](https://bluewhaletrees.com/tools/calendar/index.html.md): the months Mountain Indigobush flowers and fruits, in the grid for every species.