showy rattlebox
Crotalaria spectabilis · Fabaceae
showy rattlebox (Crotalaria spectabilis) is a annual herbaceous plant in the Fabaceae family. It is introduced to North America rather than native. USDA records it as hardy in zone 7 and warmer, down to about 7°F.
At a glance
| Type | forb-herb USDA |
|---|---|
| Lifecycle | annual USDA |
| Native status | introduced USDA |
| Mature height | 5 ft USDA |
| Light | full-sun USDA |
| Water need | medium USDA |
| Growth rate | rapid USDA |
| Soil pH | 4.9–8 USDA |
| Bloom | July USDA |
| Flower color | Yellow USDA |
| Hardiness zones | 7 and warmer USDA |
| Guild layer | nutrient 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 needs full sun. 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 4.9 to 8 — a broad range that spans acidic through mildly alkaline ground. Its cold limit is zone 7.
Size and growth
At maturity it reaches about 5 ft, making it roughly waist to chest height. It grows quickly.
Bloom period
USDA records a bloom period of July. Flowers are yellow.
A flowering date, not a pollinator rating.
Foliage, flower and season
Summer foliage is green, medium 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 spring, summer, fall.
What the site needs to provide
USDA records it across sites receiving 35 to 111 inches of annual precipitation. It needs at least 200 frost-free days to finish its season. It roots to at least 18 inches. Fertility requirement: medium.
Propagating it
Seed is the only propagation method USDA lists. Division and cuttings are not listed as options. USDA records no cold-stratification requirement, so seed should germinate without a chilling period. Its seed spreads at a moderate 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 low. Its growth form is recorded as single crown.
Role in a guild
Nutrient layer. In a layered planting this is it contributes to soil fertility rather than to structure. The layer is derived by a fixed rule from growth habit and mature height.
Tags
Related plants
Others in Crotalaria
- sunn hemp Crotalaria juncea
Similar role and hardiness
- zarzabacoa comun Desmodium incanum
- bird's-foot trefoil Lotus corniculatus
- subterranean clover Trifolium subterraneum
- arrowleaf clover Trifolium vesiculosum
Where this data comes from
Every value on this page comes from the USDA PLANTS database record for symbol CRSP2, 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, 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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