How to have pristine dahlia blooms during the dog days of summer and peak pest pressure

Dahlias bring beauty and color to the garden, but they also attract hungry visitors. Grasshoppers, Japanese beetles, and earwigs are among the most common pests that damage dahlia blooms. While chemical sprays may provide a quick fix, they can also harm pollinators and beneficial insects that keep your garden healthy. A better approach is to protect your flowers with sustainable, eco-friendly strategies that work in the short, medium, and long term.

Identifying the Damage

• Grasshoppers: Chew large, irregular holes in petals and leaves.

• Japanese beetles: Skeletonize petals, leaving lacy damage and ragged edges.

• Earwigs: Create smaller notches or scattered holes, often feeding at night.

Recognizing the type of damage helps you accurately diagnose which pest is affecting your dahlias.

 

Short-Term Solution: Protect Blooms with Organza Bags

For immediate protection, cover developing buds and blooms with organza bags. These lightweight, breathable covers prevent pests from chewing petals while still allowing sunlight and airflow. They are inexpensive, reusable, and perfect for preserving show-quality flowers or blooms destined for arrangements. These bags come in different sizes, 6”x9”, 8”x12”, and 12”x16” for different size blooms in your garden.

Medium-Term Solution: Boost Plant Health with Hi-BRIX Molasses

Pests are naturally more attracted to plants with low BRIX scores—a measure of sugar and mineral content in plant sap. By increasing BRIX, dahlias become healthier, more nutrient-dense, and less appealing to insects.

How to Apply Hi-BRIX Molasses:

• Soil Drench: Mix 1–2 tablespoons per gallon of water and pour at the base of each plant to feed soil microbes.
• Foliar Spray: Mix 1 tablespoon per gallon of water and spray leaves early morning or late evening.

Timing:

• Apply every 2–3 weeks during the growing season once dahlias are established.
• Stop applications once the dahlias are ready to bloom.
• For best results, pair molasses with compost tea or microbial inoculants to supercharge soil biology.

Long-Term Solution: Build Soil Health with Compost and Cover Crops

The strongest defense against pests is resilient, nutrient-rich soil that produces vigorous plants. Over time, improving soil health reduces pest pressure naturally.

Using Compost:

• Add 2–3 inches of finished compost to beds in spring before planting and again in fall after dahlias are lifted.
• Lightly incorporate into the top 4–6 inches of soil.
• Avoid adding more than 4 inches in a single year—steady, moderate applications are most effective and are best used in the early years of preparing your garden unless you can get compost cheaply as it can become quite expensive.

Using Cover Crops:

• Fall Planting: Sow clover, vetch, or winter rye after dahlias are removed to protect soil over winter and add organic matter.

• Spring/Summer Planting: If a bed sits empty, plant buckwheat or oats for quick soil improvement.

• A relatively low cost solution.

Termination of cover crops:

• Mow, weed whack, or cut down cover crops when they begin to flower, before they set seed.
• Leave the clippings as mulch or lightly work them into the topsoil.

• Plant into the clippings.

Final Thoughts

Managing grasshoppers, Japanese beetles, and earwigs doesn’t require chemicals that harm pollinators or wildlife. A layered approach—short-term protection with organza bags, medium-term resilience through hi-BRIX molasses, and long-term soil building with compost and cover crops—creates healthier dahlias and a thriving garden ecosystem.

By working with nature instead of against it, your dahlias will not only survive but flourish, producing strong, vibrant blooms year after year.