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How to Grow Imperial Blue Plumbago

Imperial Blue Plumbago

Plumbago auriculata 'Imperial Blue'

shrub

Imperial Blue Plumbago is a tropical to subtropical flowering shrub prized for its vibrant deep blue flowers that appear in clusters throughout the growing season. This cultivar is a selection of Cape Plumbago known for producing more intensely colored blooms than the species. It's an excellent choice for warm climates, containers, or as a specimen plant in gardens where year-round color is desired.

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Example Imperial Blue Plumbago timeline · Pittsburgh, PA (Zone 6b)

  1. Plant Imperial Blue Plumbago

    Around Apr 17

    Near Pittsburgh's average last spring frost.

  2. Tend & protect

    Late spring–summer

    Watering, feeding, and pest-watch reminders.

  3. Harvest Imperial Blue Plumbago

    Around Jul 16

    ≈ 90 days after planting

Sample dates for Pittsburgh, PA. Sign up to get exact Imperial Blue Plumbago dates for your own zip code.

Growing Conditions

☀️
Sun: Full sun, 6-8 hours of direct sunlight daily for optimal flowering
💧
Water: Moderate watering; keep soil consistently moist during growing season but allow to dry slightly between waterings. Reduce watering in winter. Once established, fairly drought-tolerant but blooms better with regular watering.
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Spacing: 36 inches
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Days to maturity: 90-120 days from planting to first significant flowering
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Planting depth: Plant at same depth as container; top of root ball level with soil surface

Soil

Type: Well-draining loamy soil with good organic content
pH: 6.0-7.0
Amendments:
Compost Peat moss or coconut coir Perlite or coarse sand for drainage

Growing Zones

Find your zone →

Zones 9b-11; can be grown in zone 9a with winter protection or as a container plant brought indoors

9b 10a 10b 11a 11b

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Growth Stages

1

Establishment

3-4 weeks

Young plant settling in with initial leaf growth and root development; may appear slow-growing initially.

Water regularly to keep soil moist but not waterlogged. Protect from strong winds. Provide bright, indirect light for first 2-3 weeks if recently transplanted.

2

Vegetative Growth

2-3 months

Vigorous stems and leaf development; plant fills out and grows taller, producing abundant green foliage.

Apply balanced fertilizer monthly. Pinch back growing tips to encourage bushier, more compact growth. Ensure adequate sunlight.

3

Budding

2-4 weeks

Flower buds form at branch tips; clusters of small buds become visible among foliage.

Maintain consistent watering and increase potassium-rich fertilizer (higher 'K' number). Do not overwater as this can reduce flowering.

4

Flowering

3-6 months (spring to fall in warm climates; year-round in frost-free areas)

Clusters of vibrant deep blue flowers with pale centers open progressively; continuous blooming occurs in warm conditions.

Deadhead spent flowers to encourage more blooms. Continue regular watering and fertilizing every 2-3 weeks with flowering fertilizer.

5

Dormancy/Winter Rest

2-4 months (November-February in northern zones)

Growth slows or stops; foliage may thin; flowering ceases or greatly reduces in colder zones.

Reduce watering significantly. Do not fertilize. In zones 9a-9b, protect with mulch or move containers indoors. Can be pruned back by 1/3 in late winter to rejuvenate.

Companion Planting

Plan your garden →

Plant with:

Salvia Lantana Bougainvillea Desert marigold Esperanza Rosemary

Avoid planting near:

Allelopathic plants that compete for nutrients Plants requiring consistently wet soil

Common Pests

  • Spray with insecticidal soap or neem oil; encourage natural predators like ladybugs; increase air circulation

  • Mist foliage regularly to increase humidity; spray with neem oil; prune affected foliage

  • Manually remove with soft brush; apply horticultural oil spray; treat with insecticidal soap

  • Spray with insecticidal soap or neem oil; isolate infested plants; use alcohol on cotton swab for small infestations

Uses

🍳

Edible flowers

Culinary

The deep blue flowers are mildly flavored and can be used as an edible garnish for cocktails, desserts, or salads, adding visual appeal and a delicate floral note. [source]

💊

Traditional herbal remedy

Medicinal

In traditional African and Asian medicine, Plumbago species have been used to treat various ailments including skin conditions, wounds, and inflammation, though scientific evidence is limited. [source]

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Ornamental landscaping

Household

Imperial Blue Plumbago is primarily grown as a stunning landscape accent plant, specimen shrub, or container plant, providing months of deep blue blooms in warm climates and adding vertical interest to gardens. [source]

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Pollinator attraction

Wildlife

The flower clusters attract butterflies, hummingbirds, and bees, making it an excellent plant for supporting pollinator populations and creating a vibrant garden ecosystem. [source]

This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.

Harvest Tips

This is an ornamental flowering shrub, not a harvested plant. Enjoy blooms fresh on the plant. Cut flowers can be brought indoors but have short vase life (2-3 days). Deadhead spent flower clusters regularly (every 1-2 weeks during bloom season) to promote continuous flowering throughout the season.

Fun Facts

  • 🌱 Imperial Blue Plumbago's flowers change color slightly as they age, opening in deep blue and fading to pale blue or white, creating a beautiful multi-toned effect in flower clusters.
  • 🌱 The name 'Plumbago' comes from the Latin word 'plumbum' (lead), historically referring to a mistaken belief that the plant could treat lead poisoning.
  • 🌱 This cultivar can be trained as a small tree or formal espalier in frost-free regions, offering versatility in landscape design beyond its typical shrub form.

Gardening Terms

New to gardening? Learn about terms used in this guide:

Cultivar Deadhead Full Sun Mulch Pinch Back Transplant
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