The warm, sheltered, predator-free environment that helps your plants also helps pests — and with no weather or natural enemies to knock them back, small infestations explode fast under cover. Greenhouse pest control is mostly about prevention, early detection and, increasingly, biological controls. This guide covers the approach; each pest has its own detailed page.
Why pests thrive in greenhouses
Constant warmth speeds up pest life cycles, the enclosed space excludes natural predators, and plants are often crowded — so populations build quickly and spread plant to plant. Vigilance beats cure.
The common greenhouse pests
- Whitefly — the classic greenhouse pest; clouds of tiny white flies under leaves.
- Spider mites — thrive in hot, dry greenhouse air; fine stippling and webbing.
- Aphids, mealybugs, thrips and scale — all common under cover.
- Fungus gnats — in damp propagation mix.
Prevention and monitoring
- Inspect new plants before bringing them in; quarantine suspects.
- Yellow/blue sticky traps monitor and reduce flying pests early — see sticky traps.
- Good airflow and spacing, and keeping the greenhouse weed-free, reduce hiding spots.
- Manage humidity/heat — spider mites love hot, dry air, so damping down can help.
Biological control
The enclosed greenhouse is actually ideal for biological controls — introduced predators and parasites (for whitefly, spider mite, aphid and more) that stay put and do the work. Introduce them early, before pests peak, and avoid broad-spectrum sprays that kill the beneficials too. Where you do treat, use targeted, labelled products and a sprayer.
Quick questions
What is the most common greenhouse pest? Whitefly, followed by spider mites and aphids — all build up fast in the warm, enclosed space, so monitor with sticky traps and act early.
Related guides
If something looks wrong with the plant beyond this, see our plant problems diagnosis guide.
