A greenhouse gives your plants a protected place to grow, but that same warm, sheltered environment can also attract pests. Aphids, whiteflies, spider mites, thrips, fungus gnats, scale insects, and mealybugs can spread quickly if they are not caught early.
The good news? With regular inspection, proper ventilation, smart watering habits, and natural pest control methods, you can keep your greenhouse healthy without relying on harsh chemicals.
In this guide, we’ll cover the most common greenhouse pests, how to identify them, and the best natural ways to prevent and control them.
What is the best way to control pests in a greenhouse?
The best way to control pests in a greenhouse is to use an integrated approach. Inspect plants regularly, remove damaged leaves, avoid overwatering, improve airflow, use sticky traps, introduce beneficial insects, and treat infestations early with options like insecticidal soap or neem oil.
This approach works better than relying on a single solution because greenhouse pests often thrive when several conditions overlap, including excess moisture, poor airflow, overcrowding, and stressed plants. For a deeper look at how climate affects pests and disease, read our guide on how to prevent greenhouse pests year-round.
What Are the Most Common Greenhouse Pests?
The most common greenhouse pests include aphids, spider mites, whiteflies, thrips, fungus gnats, scale insects, and mealybugs. These pests can damage leaves, stems, flowers, roots, and fruit, especially when plants are stressed or crowded.
| Pest | Common Signs | Best Natural Controls |
|---|---|---|
| Aphids | Curled leaves, sticky residue, clusters under leaves | Ladybugs, lacewings, neem oil, insecticidal soap |
| Spider mites | Fine webbing, yellow stippling, dry leaves | Predatory mites, water spray, neem oil, humidity control |
| Whiteflies | Small white flying insects, sticky honeydew, sooty mold | Yellow sticky traps, Encarsia formosa, insecticidal soap |
| Thrips | Silvery streaks, distorted leaves, and flower damage | Blue sticky traps, predatory mites, and neem oil |
| Fungus gnats | Small flies near soil, weak seedlings | Let the soil dry, use yellow sticky traps, and beneficial nematodes |
| Scale insects | Small bumps on stems or leaves, yellowing leaves | Pruning, insecticidal soap, and neem oil |
| Mealybugs | White cottony clusters, sticky residue | Manual removal, neem oil, beneficial insects |
How to Identify and Get Rid of Common Greenhouse Pests
1. Aphids
Aphids are small, soft-bodied insects that often gather on the undersides of leaves and tender new growth. They feed on plant sap, which can cause curled leaves, distorted growth, and sticky honeydew.
How to get rid of aphids naturally:
- Spray plants with water to knock aphids loose.
- Introduce ladybugs or lacewings.
- Apply insecticidal soap to affected leaves.
- Use neem oil according to label instructions.
- Remove heavily infested leaves before the problem spreads.
2. Spider mite
Spider mites are tiny, eight-legged pests that thrive in warm, dry conditions. They often leave fine webbing between leaves and cause pale yellow speckling on foliage.
How to control spider mites naturally:
- Increase humidity around affected plants when appropriate.
- Rinse leaves, especially undersides.
- Introduce predatory mites such as Phytoseiulus persimilis.
- Use insecticidal soap or neem oil.
- Remove badly damaged leaves.
3. Whiteflies
Whiteflies are small flying insects that gather on the undersides of leaves. When disturbed, they often flutter up in a cloud. Like aphids, they feed on sap and can leave behind sticky honeydew that encourages sooty mold.
How to control whiteflies naturally:
- Hang yellow sticky traps near affected plants.
- Spray the undersides of leaves with insecticidal soap.
- Use neem oil as directed.
- Introduce beneficial insects such as Encarsia formosa.
- Remove weeds and plant debris that may harbor pests.
4. Thrips
Thrips are slender insects that scrape plant tissue, leaving silvery or bronze streaks on leaves and flowers. They can also spread plant viruses, making early control especially important.
How to control thrips naturally:
- Use blue or yellow sticky traps for monitoring.
- Remove damaged flowers and leaves.
- Introduce predatory mites such as Amblyseius cucumeris.
- Apply insecticidal soap or neem oil.
- Keep weeds under control inside and around the greenhouse.
5. Fungus gnats
Fungus gnats are small flies often found hovering near moist soil. Adult gnats are mostly a nuisance, but larvae can damage young roots and seedlings.
How to control fungus gnats naturally:
- Let the top layer of soil dry between waterings.
- Avoid leaving standing water in trays.
- Use yellow sticky traps to catch adults.
- Apply beneficial nematodes such as Steinernema feltiae.
- Improve drainage in pots and raised beds. Planta Greenhouses garden beds help make an organized growing space.
6. Scale insects
Scale insects look like small, flat or raised bumps on stems and leaves. They feed on sap, which can weaken plants and cause yellowing leaves or stunted growth.
How to control scale naturally:
- Prune heavily infested stems.
- Gently scrape small infestations from stems.
- Apply insecticidal soap or horticultural oil.
- Use neem oil as directed.
- Inspect nearby plants because scale can spread slowly and quietly.
7. Mealybugs
Mealybugs are soft-bodied insects covered in a white, waxy coating. They often hide in leaf joints, stems, and protected areas of plants.
How to control mealybugs naturally:
- Dab small clusters with rubbing alcohol on a cotton swab.
- Prune heavily infested growth.
- Spray affected areas with insecticidal soap.
- Use neem oil as directed.
- Introduce beneficial insects such as lacewings or mealybug destroyers.
Natural Greenhouse Pest Control Methods
Inspect Plants Regularly
Check leaves, stems, flowers, soil surfaces, and the undersides of leaves at least once a week. Look for sticky residue, webbing, tiny flying insects, yellowing leaves, holes, or distorted growth. A small magnifying glass can help you spot tiny pests like mites and thrips.
Use Sticky Traps for Monitoring
Sticky traps are useful for catching and monitoring flying pests like fungus gnats, whiteflies, aphids, and thrips. Place them near plant canopies, doors, vents, and problem areas. Use yellow sticky traps for whiteflies and fungus gnats, and blue traps when monitoring thrips.
Sticky traps are best used as an early warning system, not as your only control method.
Introduce Beneficial Insects
Beneficial insects can help keep pest populations under control naturally. Ladybugs and lacewings feed on aphids, predatory mites target spider mites and thrips, and parasitic wasps can help with whiteflies.
Improve Airflow and Ventilation
Good airflow helps reduce the warm, stagnant conditions that many pests love. Open doors and vents when the weather allows, use fans to keep air moving, and avoid overcrowding plants. Planta Greenhouse roof vents, side vents, fans, and ventilation bundles can help create a healthier growing environment.
Water Carefully
Overwatering creates damp soil that attracts fungus gnats and can weaken plant roots. Water deeply when needed, then allow the top layer of soil to dry before watering again. Good drainage is especially important in pots, trays, and raised beds.
Keep Your Greenhouse Clean
Remove dead leaves, fallen fruit, weeds, and old plant debris. Clean pots and trays before reusing them, and keep walkways and shelves tidy. A clean greenhouse gives pests fewer places to hide and reproduce.
Quarantine New Plants
Before adding new plants to your greenhouse, keep them separate for several days and inspect them closely. Check the undersides of leaves, stems, and soil surface for eggs, larvae, webbing, or sticky residue. This simple step can prevent a single infested plant from spreading pests throughout the entire greenhouse.
Companion Plants That May Help Deter Greenhouse Pests
Some greenhouse gardeners add aromatic herbs and flowers to help confuse or deter pests while attracting pollinators and beneficial insects. Companion planting works best when paired with regular scouting, good airflow, and proper watering.
Good options include:
- Marigolds: Often used near vegetables and flowers to support pollinators and help deter some pests.
- Basil: A useful greenhouse herb that may help discourage flies and some soft-bodied insects.
- Chives, garlic, and onions: Strong-scented alliums that can be planted near vulnerable crops.
- Lavender and rosemary: Aromatic herbs that may help discourage flying insects.
- Mint: Can deter some pests, but grow it in containers because it spreads aggressively.
For more ideas, explore these pest-repelling plants for your greenhouse.
Weekly Greenhouse Pest Prevention Checklist
- Check the undersides of leaves.
- Look for sticky honeydew, webbing, larvae, or leaf discoloration.
- Remove dead leaves and plant debris.
- Empty standing water from trays.
- Check sticky traps.
- Prune overcrowded plants.
- Make sure vents and fans are working.
- Inspect new plants before bringing them inside.
- Clean tools, pots, and trays after use.
- Act quickly when you spot early signs of pests.
Greenhouse Pest Control FAQs
1. What are the most common greenhouse pests?
The most common greenhouse pests include aphids, spider mites, whiteflies, thrips, fungus gnats, scale insects, and mealybugs. Other pests to watch for include caterpillars, leafminers, slugs, and snails.
2. How do I get rid of pests in a greenhouse naturally?
Use a combination of regular inspections, sticky traps, beneficial insects, insecticidal soap, neem oil, careful watering, good ventilation, and sanitation. This integrated approach is stronger than relying on a single treatment.
3. Are sticky traps enough for greenhouse pest control?
Sticky traps help monitor and reduce flying pests, but they are not enough on their own. Use them with plant inspections, sanitation, beneficial insects, and targeted treatments.
4. Can I use neem oil in a greenhouse?
Yes, neem oil is commonly used against soft-bodied pests such as aphids, whiteflies, spider mites, scale, and mealybugs. Always follow the product label, test a small area first, avoid spraying during extreme heat, and do not overapply.
5. How do I prevent pests from entering my greenhouse?
Keep doors and vents screened when possible, quarantine new plants, clean tools and pots, remove weeds and plant debris, avoid overwatering, and inspect your plants regularly.
Build a Healthier Growing Space With Planta Greenhouses
Pest control starts with a greenhouse environment that is easy to manage. Planta Greenhouses are built with durable galvanized steel frames, UV-protected polycarbonate panels, and ventilation-friendly designs that help gardeners create a protected, productive space in every season.
Whether you’re growing vegetables, herbs, flowers, or seedlings, the right greenhouse setup can make it easier to manage airflow, moisture, cleanliness, and plant health.
Explore Planta greenhouse kits and accessories to create a growing space that supports healthier plants from season to season.