Crape Myrtle Cultivation: Intermediate Growing Techniques

Advanced Crape Myrtle Growing

Building on basic knowledge, this intermediate guide explores the rich diversity of crape myrtle species and cultivars, the science behind hybrid development, proper pruning techniques, and comprehensive disease management.

Understanding Crape Myrtle Taxonomy

Genus Lagerstroemia

Key Species in Horticulture

The Hybrid Revolution

Lagerstroemia indica × L. fauriei hybrids:

Why L. fauriei was crossed:

• Superior powdery mildew resistance
• Better bark exfoliation
• More tree-like form
• Cold hardiness

National Arboretum "Indian Tribe" Series:

Comprehensive Variety Selection

By Disease Resistance

By Cold Hardiness

By Bark Quality

Newer Cultivar Series

Black Diamond Series:

• Near-black foliage
• Compact growth
• Bright flower colors
• Good disease resistance

Enduring Summer Series:

• Improved cold hardiness
• Extended bloom period
• Disease resistant

Proper Pruning Techniques

Pruning Philosophy

The goal is to enhance natural form, not control size. If you need a smaller tree, choose a smaller variety.

When to Prune

Structural Pruning Guide

For young trees (first 3-5 years):

1. Select 3-7 well-spaced trunks
2. Remove competing leaders
3. Eliminate crossing branches
4. Remove suckers at base
5. Clear interior for air circulation

For mature trees:

1. Maintain selected trunks
2. Thin interior branches annually
3. Remove dead or damaged wood
4. Control suckers
5. Preserve natural form

Correcting "Crape Murder"

If a tree has been topped:

1. Year 1: Remove weak, crowded sprouts; keep 2-3 best per stub
2. Year 2: Thin to 1 dominant shoot per cut point
3. Year 3+: Continue training selected shoots
4. Consider: Cutting back to 12-24" and starting fresh

Rejuvenation Pruning

For overgrown or misshapen trees:

1. Cut all trunks to 12-24" in late winter
2. Allow new growth
3. Select 3-7 new shoots
4. Remove others
5. Train new structure over 2-3 years

Disease Management

Powdery Mildew

Cause: Erysiphe lagerstroemiae

Conditions favoring:

• High humidity
• Poor air circulation
• Shade
• Crowded plantings

Symptoms:

• White powder on leaves, buds, shoots
• Distorted growth
• Premature leaf drop

Management:

Cercospora Leaf Spot

Cause: Cercospora lythracearum

Symptoms:

• Dark spots on leaves
• Yellow halos
• Premature defoliation

Management:

• Remove fallen leaves
• Improve air circulation
• Fungicide in severe cases

Crape Myrtle Bark Scale (CMBS)

Pest: Acanthococcus lagerstroemiae

Origin: Introduced from Asia (first detected 2004)

Symptoms:

• White, waxy encrustations on bark
• Black sooty mold from honeydew
• Reduced vigor

Management:

Propagation Methods

Softwood Cuttings

Timing: Late spring to early summer

Process:

1. Take 6-8 inch cuttings from new growth
2. Remove lower leaves
3. Dip in rooting hormone (IBA 3000-5000 ppm)
4. Insert in sterile medium
5. Maintain high humidity
6. Root in 6-10 weeks

Success rate: 60-90%

Hardwood Cuttings

Timing: Late fall to winter (dormant)

Process:

1. Take 6-12 inch cuttings from previous year's growth
2. Treat with hormone (optional)
3. Plant in protected outdoor bed
4. Root development over winter
5. Transplant following fall

Seed Propagation

• Seeds germinate easily
• Seedlings variable
• Not used for cultivar reproduction
• Useful for breeding

Year-Round Interest Planning

Seasonal Features

Companion Planting

Troubleshooting Advanced Issues

Next Steps

1. Learn hybrid advantages
2. Master proper pruning
3. Develop disease prevention program
4. Experiment with cultivar selection
5. Create multi-season landscape interest

Understanding these intermediate concepts enables you to grow crape myrtles to their full potential.