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How to Grow Arthur Johnson Clematis

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Arthur Johnson Clematis

Clematis x jackmanii 'Arthur Johnson'

vine

Arthur Johnson is a large-flowered clematis vine known for its vibrant crimson-red flowers with prominent dark stamens. This deciduous woody climber produces abundant blooms throughout summer and early fall, making it a stunning ornamental for trellises, arbors, and garden structures.

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Example Arthur Johnson Clematis timeline · Pittsburgh, PA (Zone 6b)

  1. Plant Arthur Johnson Clematis

    Around Apr 17

    Near Pittsburgh's average last spring frost.

  2. Tend & protect

    Late spring–summer

    Watering, feeding, and pest-watch reminders.

  3. Harvest Arthur Johnson Clematis

    Late summer into fall

    Before the first fall frost (≈ Nov 8)

Sample dates for Pittsburgh, PA. Sign up to get exact Arthur Johnson Clematis dates for your own zip code.

Growing Conditions

☀️
Sun: Full sun to partial shade; at least 6 hours of direct sunlight daily for best flowering
💧
Water: Keep soil consistently moist but not waterlogged; water deeply 1-2 times weekly during growing season; reduce in winter
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Spacing: 36 inches
📅
Days to maturity: Flowers appear in first year; reaches full maturity in 2-3 years
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Planting depth: Plant root ball at same depth as container; stem can be buried 2 inches deeper to encourage basal growth

Soil

Type: Well-draining loamy soil with organic matter
pH: 6.5-7.5
Amendments:
Compost aged bark mulch peat moss lime if acidic

Growing Zones

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Zones 5-9; prefers cooler climates with consistent moisture

5a 5b 6a 6b 7a 7b 8a 8b 9a

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Growth Stages

1

Establishment

2-4 weeks

Young vines developing root system and initial shoots; typically 1-2 feet of growth

Keep soil consistently moist; provide sturdy support structure; protect from harsh winds; mulch around base but keep away from stem

2

Vegetative Growth

4-8 weeks

Vigorous shoot and leaf production as vine extends along support; reaches 6-12 feet in first season

Guide tendrils to trellis; prune competing shoots; maintain consistent moisture; fertilize monthly with balanced fertilizer

3

Flowering (Main)

6-8 weeks (June-July)

Large (4-6 inch) crimson-red flowers with dark centers appear on new growth; prolific blooming

Deadhead spent flowers to encourage continuous blooming; maintain regular watering; provide afternoon shade in hot climates

4

Second Flush (Late Summer)

4-8 weeks (August-September)

Secondary wave of flowers appears on new growth in late summer through fall

Continue deadheading; reduce fertilizer in late summer; maintain consistent watering

5

Dormancy

November-March

Foliage yellows and falls; woody stems remain visible on support structure

Cut back hard in late winter to 12-18 inches above ground or to strong buds; clean up fallen debris; minimal watering

Companion Planting

Plan your garden →

Plant with:

Roses Lavender Salvia Russian sage Catmint Ornamental grasses

Avoid planting near:

Black walnut trees Mint species (can compete aggressively)

Common Pests

  • Remove affected stems immediately; improve air circulation; avoid overhead watering; plant deeper to promote basal regeneration

  • Spray with water to dislodge; use neem oil or insecticidal soap in severe cases; increase humidity around plant

  • Improve air circulation; avoid wetting foliage; spray with fungicide or sulfur dust; remove heavily infected leaves

  • and

    Remove by hand; apply copper tape around support structures; use beer traps; encourage natural predators like ground beetles

Uses

🏠

Ornamental garden structure cover

Household

Arthur Johnson clematis creates stunning vertical interest on trellises, arbors, pergolas, and fences with its profusion of vibrant crimson flowers. Perfect for screening unsightly views or creating romantic garden focal points. [source]

🦋

Pollinator attraction

Wildlife

The abundant flowers attract bees, butterflies, and hummingbirds throughout summer and fall, providing valuable nectar sources during peak bloom periods. [source]

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Cut flower arrangements

Craft

Large, showy blooms are excellent for fresh floral arrangements, adding dramatic color and texture to bouquets and decorative displays. [source]

Harvest Tips

Not typically harvested for culinary purposes; deadhead spent blooms to encourage continuous flowering throughout season; cut flowers can be enjoyed in arrangements when fully open

Fun Facts

  • 🌱 Arthur Johnson is a Jackmanii group clematis, a hybrid that produces flowers on new wood, making it more forgiving for gardeners who forget or perform pruning at the wrong time
  • 🌱 The name 'Arthur Johnson' honors the Scottish plant breeder and horticulturist who developed many popular clematis hybrids in the early 20th century
  • 🌱 Unlike some clematis varieties prone to wilt, Arthur Johnson is relatively disease-resistant and reliable, earning it a reputation as a clematis for beginners

Gardening Terms

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

Deadhead Full Sun Mulch Partial Shade Trellis
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