Hardy Blue Plumbago (Ceratostigma willmottianum)

Hardy Blue Plumbago

Ceratostigma willmottianum

Vivid blue blooms light up late summer, a cheerful burst of color. Deciduous flowering shrub; common name: Hardy Blue Plumbago.

Full sun
1–2/week
Beginner
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Plant Needs

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Sunlight Thrives in full sun for maximum flowering; tolerates partial shade in hot summer climates
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Watering Water deeply when the top 2 cm of soil dries out; avoid prolonged waterlogging to prevent root rot
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Temperature Hardy to -10°C; protect from extreme, prolonged frost in cold regions
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Characteristics

  • Leaf: Oval to lanceolate, bright green foliage turning bronze-red in autumn
  • Flower: Dense clusters of bright blue, five-petaled star-shaped blooms
  • Stem: Slender upright to arching stems with subtle reddish tint
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Care Guide

Watering

Keep soil evenly moist; increase watering during extended hot, dry spells

Fertilization

Apply balanced slow-release granular fertilizer once. Avoid over-fertilizing to prevent leggy, sparse growth

Banana peel tea:Soak chopped banana peels in water for 3 days; dilute 1:10 with water before applying as a root drench; discard solid peels to avoid odor and pest issues
Pruning
  • Prune back to 10–15 cm above soil level in early spring to encourage bushy, compact growth
  • Deadhead spent flower clusters to extend the flowering period
  • Remove weak, damaged, or crossing stems to improve airflow and overall plant health
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Toxicity

Warning: this plant may be toxic.

Pets & Humans

Pets: ASPCA: Non-toxic to cats with no reported adverse effects

Humans: No known toxicity to humans

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Garden Uses & Culture

Culture: N/A

Usage: Ornamental garden shrub, container plant for patios, autumn foliage accent