Spreading Phlox (Phlox diffusa)

Spreading Phlox

Phlox diffusa

Low-growing mat of starry blooms, a carpet of pastel color for rock gardens. Evergreen perennial groundcover; common name: spreading phlox.

Full sun
1–2/week
Beginner
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Plant Needs

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Sunlight Full sun to partial shade; requires at least 6 hours of direct sunlight for optimal flowering
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Watering Water when the top 2 cm of soil dries completely; avoid overwatering to prevent root rot
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Temperature Hardy to -20°C; tolerates cool summer temperatures, avoid prolonged exposure to heat above 28°C
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Characteristics

  • Leaf: Tiny, linear, evergreen leaves arranged densely along trailing stems
  • Flower: Star-shaped, 5-petaled blooms in shades of white, pink, or lavender
  • Stem: Slender, trailing stems that root at nodes to form dense, spreading mats
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Care Guide

Watering

Keep soil evenly moist during active blooming period

Fertilization

Apply diluted, balanced feed once monthly during active growth. Use low-nitrogen fertilizer to promote flowering rather than foliage growth

Eggshell powder topdress:Sprinkle a thin layer of crushed, dried eggshells around the base of plants; avoid direct contact with stems to prevent burning
Pruning
  • Deadhead spent blooms promptly to extend the flowering period
  • Trim back overgrown stems in early spring to maintain a compact mat shape
  • Remove dead or damaged foliage in fall to reduce overwintering disease risk
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Toxicity

Warning: this plant may be toxic.

Pets & Humans

Pets: ASPCA: Non-toxic to cats; no adverse effects from ingestion or contact

Humans: No known toxicity to humans; safe for handling and proximity

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Garden Uses & Culture

Culture: N/A

Usage: Groundcover for rock gardens, alpine troughs, and border edging