Peppers: Pests & Diseases
Sweet and chilli peppers crop well in a bright greenhouse or the warmest sheltered patio, provided roots are never waterlogged or allowed to dry completely. Their compact growth makes them suitable for containers, but regular checks are needed because sap-feeding pests multiply quickly under glass.
Common pests
Aphids feed on tender tips, buds and leaf undersides, leading to curled growth and sticky honeydew. Glasshouse whitefly is a regular protected-crop pest and may leave leaves coated with honeydew. Red spider mite flourishes in dry, warm air, first causing pale stippling and later fine webbing. Slugs and snails can chew newly planted peppers outdoors or in accessible pots.
Common diseases
Grey mould can infect fading flowers, damaged stems and fruit in humid, crowded conditions. Blossom end rot produces a dark, sunken patch at the base of fruit and usually follows irregular watering or poor calcium uptake rather than infection. Root rots occur in cold, saturated compost. Viral infections may cause mosaic patterns, stunting and distorted foliage, often spread by aphids.
Prevention
Use clean pots and fresh compost, or rotate greenhouse beds away from peppers, tomatoes and aubergines. Space plants so air can circulate, remove dead flowers and ventilate daily. Water evenly at the root, allowing excess water to drain freely, and avoid drastic changes in moisture. Choose vigorous, healthy plants and keep greenhouse tools clean. Protect outdoor young plants from cold winds with horticultural fleece.
Non-chemical control
Rub off or rinse away small aphid colonies and support natural predators with nearby flowering plants. Under glass, Encarsia can reduce whitefly and Phytoseiulus can be used against red spider mite. Remove and bin mouldy flowers or fruit as soon as seen. Hand-pick slugs in the evening and use physical barriers around pots or planting holes. Discard badly virus-affected plants promptly.
What to look for
Check new growth and leaf undersides each week for aphids, whitefly eggs and mite speckling; in hot weather, inspect twice weekly. Watch fruit as it swells for blossom end rot. During dull, humid periods, inspect flower remnants and stem joints for the soft grey growth of mould.
Tips
Avoid over-potting young plants and support branches once fruit develops. Gentle tapping of flowers on dry days can aid pollination under cover. Pick ripe peppers regularly so remaining fruit receives light and plants continue producing.
Peppers pests & diseases: frequently asked questions
What are the common pests of peppers?
Aphids feed on tender tips, buds and leaf undersides, leading to curled growth and sticky honeydew.
What diseases affect peppers?
Grey mould can infect fading flowers, damaged stems and fruit in humid, crowded conditions.
How do I prevent pests and diseases on peppers?
Use clean pots and fresh compost, or rotate greenhouse beds away from peppers, tomatoes and aubergines.
General guidance for UK home gardens, focused on prevention and non-chemical control. The RHS or a local garden centre can help with tricky cases. Page updated 19 Sep 2026.