mountain false indigo
Amorpha glabra · Fabaceae
mountain false indigo (Amorpha glabra) is a perennial shrub in the Fabaceae family. It is native to North America. USDA records it as hardy in zone 6 and warmer, down to about -3°F.
At a glance
| Type | shrub USDA |
|---|---|
| Lifecycle | perennial USDA |
| Native status | native USDA |
| Mature height | 16 ft USDA |
| Light | part-shade USDA |
| Water need | medium USDA |
| Growth rate | moderate USDA |
| Soil pH | 4.7–7 USDA |
| Bloom | April–May USDA |
| Flower color | Purple USDA |
| Hardiness zones | 6 and warmer USDA |
| Guild layer | shrub Derived |
| Nursery availability | Contracting Only USDA |
USDA quoted from the USDA PLANTS database · Derived computed by a fixed rule from those columns. No value on this page is estimated.
Growing conditions
It grows in partial shade. USDA rates it as having moderate water needs. Its drought tolerance is rated medium. It will not tolerate waterlogged soil — USDA rates its anaerobic tolerance as none. It is recorded on soils from pH 4.7 to 7 — a broad range that spans acidic through mildly alkaline ground. Its cold limit is zone 6.
Size and growth
At maturity it reaches about 16 ft, making it a small tree or large shrub. It grows at a moderate rate.
Bloom period
USDA records a bloom period of April through May. Flowers are purple.
A flowering date, not a pollinator rating.
Foliage, flower and season
Summer foliage is green, coarse in texture. Its flowers are conspicuous. Its active growth period is spring and summer. USDA rates its lifespan as long.
What the site needs to provide
USDA records it across sites receiving 32 to 60 inches of annual precipitation. It needs at least 150 frost-free days to finish its season. It roots to at least 20 inches. Fertility requirement: low — no feeding needed on ordinary garden soil.
Propagating it
Propagate it from seed, bare root and container stock. Seed needs cold stratification — a period of moist chilling — before it will germinate, so sow in autumn or chill it artificially before a spring sowing. Its seed spreads at a slow rate. It does not spread vegetatively, so it will stay where you put it.
Resilience and wildlife
Browsing animals find it moderately palatable, so expect deer and rabbits to take an interest. Its fire tolerance is rated high, and it can resprout after damage. Its growth form is recorded as multiple stem.
Role in a guild
Shrub layer. In a layered planting this is woody mid-level structure between the understory and the ground. The layer is derived by a fixed rule from growth habit and mature height.
Tags
Related plants
Others in Amorpha
- leadplant Amorpha canescens
- false indigo bush Amorpha fruticosa
Similar role and hardiness
- eastern baccharis Baccharis halimifolia
- mule-fat Baccharis salicifolia
- wintergreen barberry Berberis julianae
- stiff dogwood Cornus foemina
- autumn olive Elaeagnus umbellata
Where this data comes from
Every value on this page comes from the USDA PLANTS database record for symbol AMGL2, or is computed from those values by a fixed rule. Nothing here is estimated or model-generated. Where USDA publishes no value, this page omits the claim rather than filling the gap.
- Quoted from USDA PLANTS: active growth period, Bloom, Bloom end, browse palatability, cold stratification, Drought tolerance, fall conspicuous, fertility requirement, fire tolerance, Flower color, flower conspicuous, foliage color, foliage porosity winter, foliage texture, frost free days min, fruit conspicuous, growth form, Growth rate, Hardiness zones, Lifecycle, lifespan, Light, Mature height, Minimum temperature, Native status, Nitrogen fixation, Nursery availability, precipitation max in, precipitation min in, propagation, resprout ability, root depth in, seed spread rate, Soil pH, Soil pH (upper), Tolerance of wet soil, Toxicity, Type, vegetative spread rate, Water need.
- Derived by a fixed rule from those columns: Guild layer.
Read our full data sources and methodology.
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