Solving Flower Drop and Pest Infestations in Greenhouse Container Gardens

Why Flowers Drop Without Setting Fruit

When greenhouse tomatoes, peppers, or squash produce abundant flowers but no fruit, the usual culprits are poor pollination, temperature extremes, or pest damage. In a closed greenhouse, natural pollinators may be absent, and high daytime temperatures (above 90°F) can sterilize pollen.

Hand-Pollination Technique

• Use a small brush or cotton swab to transfer pollen from male to female flowers (female flowers have a tiny fruit at the base).
• Do this in the morning when pollen is most viable.
• Gently shaking tomato plants every few days also helps release pollen.

Managing Hornworms, Cabbage Worms & Other Pests

• Scout at night. Many caterpillars feed after dark; use a flashlight to find and remove them.
• Apply Bacillus thuringiensis (Bt). This organic bacterial spray targets caterpillars without harming beneficial insects.
• Use row covers. Fine mesh excludes egg-laying moths while allowing light and water through.
• Spray neem oil or insecticidal soap weekly for soft-bodied pests; apply in early morning or evening to avoid leaf burn.

Cabbage & Brussels Sprouts Recovery

If worms have heavily damaged leaves, the plants may still form heads or sprouts if the growing point is intact. Remove damaged foliage, apply Bt, and fertilize with a nitrogen-rich organic feed to encourage new growth.

Greenhouse Sanitation

• Remove all plant debris and weeds nightly.
• Spray perimeter and floor with a pyrethrin-based spray (organic) to reduce pest migration.
• Introduce beneficial insects like ladybugs or parasitic wasps for ongoing control.

A clean, well-ventilated greenhouse with active pollination and organic pest management will yield a bountiful harvest.