false indigo bush
Amorpha fruticosa · Fabaceae
false indigo bush (Amorpha fruticosa) is a perennial shrub in the Fabaceae family. It is native to North America. USDA records it as hardy in zone 3 and warmer, down to about -38°F.
⚠ Invasive or noxious status. USDA lists this plant with an invasive or noxious weed status somewhere in its range. Check your state's noxious weed list before planting it — in some states it is illegal to sell or plant.
Both flags are quoted from USDA PLANTS, not inferred.
At a glance
| Type | shrub USDA |
|---|---|
| Lifecycle | perennial USDA |
| Native status | native USDA |
| Mature height | 15 ft USDA |
| Light | full-sun USDA |
| Water need | low USDA |
| Growth rate | slow USDA |
| Soil pH | 5–8.5 USDA |
| Bloom | May–June USDA |
| Flower color | Purple USDA |
| Hardiness zones | 3 and warmer USDA |
| Guild layer | shrub Derived |
| Nursery availability | Routinely Available 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 needs full sun. USDA rates it as having low water needs once established. 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 5 to 8.5 — a broad range that spans acidic through mildly alkaline ground. Its cold limit is zone 3.
Size and growth
At maturity it reaches about 15 ft, making it a small tree or large shrub. It grows slowly.
Bloom period
USDA records a bloom period of May through June. Flowers are purple.
A flowering date, not a pollinator rating.
Foliage, flower and season
Summer foliage is yellow-green, fine in texture. Its flowers are conspicuous. It carries conspicuous autumn colour. Its fruit or seed heads are conspicuous, extending interest past flowering. Its active growth period is summer. USDA rates its lifespan as moderate.
What the site needs to provide
USDA records it across sites receiving 10 to 65 inches of annual precipitation. The low end of that band is genuinely arid, so it has a wide tolerance for dry country. It needs at least 100 frost-free days to finish its season. It roots to at least 24 inches. Fertility requirement: low — no feeding needed on ordinary garden soil.
Propagating it
It takes readily from seed, cuttings, 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 rapid rate. It does not spread vegetatively, so it will stay where you put it.
Resilience and wildlife
Browsing animals rate it barely palatable — the sourced basis for calling it deer-resistant. Its fire tolerance is rated none, 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
- mountain false indigo Amorpha glabra
Similar role and hardiness
- moundscale Atriplex ×aptera
- shadscale saltbush Atriplex confertifolia
- Gardner's saltbush Atriplex gardneri
- bog birch Betula pumila
- Siberian peashrub Caragana arborescens
Where this data comes from
Every value on this page comes from the USDA PLANTS database record for symbol AMFR, 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, Invasive status, 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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