Many-seeded Rattlebox (Crotalaria polysperma)

Many-seeded Rattlebox

Crotalaria polysperma

Its pea-like blooms hold quiet prairie charm, with seed pods that rattle when dry. Herbaceous annual legume; common name: many-seeded rattlebox.

Full sun
1–2/week
Moderate
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Plant Needs

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Sunlight Thrives in full sun; tolerates partial shade but produces fewer blooms in low light conditions
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Watering Water deeply when the top 2–3 cm of soil is dry; avoid overwatering to prevent root rot
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Temperature Requires warm temperatures; cannot tolerate frost, so avoid exposure below 10°C
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Characteristics

  • Leaf: Simple, oblong to lanceolate leaves with smooth margins; pale to medium green
  • Flower: Clusters of small, bright yellow pea-like flowers in terminal racemes
  • Fruit: Slender cylindrical seed pods that rattle when mature, containing numerous tiny seeds
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Care Guide

Watering

Keep soil consistently moist but not waterlogged; increase frequency during hot, dry spells

Fertilization

Apply diluted balanced fertilizer once every 2 weeks. Avoid over-fertilizing, as excessive nitrogen can reduce flowering

Composted banana peel tea:Soak fully composted banana peels in water for 24 hours, dilute 1:20 for root drench; discard solid debris to prevent pest infestations and odor
Pruning
  • Deadhead spent blooms regularly to encourage continuous flowering throughout the growing season
  • Thin overcrowded stems to improve airflow and reduce the risk of fungal infections
  • Cut back the entire plant after flowering to collect seeds or clear garden debris for the next growing season
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Toxicity

Warning: this plant may be toxic.

Pets & Humans

Pets: ASPCA: Toxic; ingestion may cause vomiting, diarrhea, lethargy, and liver failure

Humans: Contains pyrrolizidine alkaloids; ingestion can cause liver damage with repeated exposure

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Garden Uses & Culture

Culture: N/A

Usage: Used as a cover crop to fix nitrogen in soil; ornamental in wildflower meadows