Prairie Gromwell (Lithospermum diffusa)

Prairie Gromwell

Lithospermum diffusa

It spreads low and bright, a carpet of tiny blue blooms. Low-growing perennial wildflower; common name: Prairie Gromwell.

Full sun
1/week
Beginner
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Plant Needs

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Sunlight Full sun to partial shade; performs best in open, sunny prairie-like conditions
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Watering Drought-tolerant; water only during prolonged dry periods to avoid root rot
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Temperature Extremely cold-hardy; withstands hot, arid summer temperatures without supplemental water
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Characteristics

  • Leaf: Narrow linear to lanceolate gray-green leaves, densely covered in fine hairs for drought resistance
  • Flower: Tiny funnel-shaped blue to pale purple blooms, clustered at stem apices
  • Stem: Slender, trailing or spreading stems with soft pubescence
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Care Guide

Watering

Water sparingly only when soil is completely dry

Fertilization

Optional diluted compost tea once monthly. No regular fertilization required; excess nutrients may reduce flowering

Eggshell powder topdressing:Crush thoroughly washed, dried eggshells into fine powder; sprinkle lightly over soil surface to boost calcium levels without overfeeding
Pruning
  • Trim spent flower stems after blooming to maintain tidy growth
  • Remove dead foliage in early spring to promote new shoot emergence
  • Thin overcrowded mats to improve airflow and reduce disease risk
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Toxicity

Warning: this plant may be toxic.

Pets & Humans

Pets: ASPCA: No documented toxicity to cats

Humans: No known toxic effects to humans; safe for handling and consumption in small quantities

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Garden Uses & Culture

Culture: N/A

Usage: Pollinator-friendly wildflower; low-growing ground cover for rock gardens