All products were chosen independently by our editorial team. This review contains affiliate links and we may receive a commission for purchases made. Please read our affiliates FAQ page to find out more.
Red spider mites and webbing visible on plant leaves

Red spider mites

Learn organic methods to control red spider mites, in our expert guide.

A table displaying which months are best to sow, plant and harvest.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Time to act
Time to act

Do Time to act in January

Do Time to act in February

Do Time to act in March

Do Time to act in April

Do Time to act in May

Do Time to act in June

Do Time to act in July

Do Time to act in August

Do Time to act in September

Do Time to act in October

Do Time to act in November

Do Time to act in December

Spider mites are tiny, sap-sucking pests, related to spiders. They may be only 0.5mm long but they can wreak havoc in a greenhouse or on house plants indoors. The most common spider mite in the UK is red spider mite, also know as two-spotted mite. For most of the year they are a pale green colour with two dark spots on their back, but in autumn and winter they turn orange-red and may be spotted in cracks in windowsills and in our homes, as they look for places to hibernate. Spider mites thrive in hot, dry conditions so life in the greenhouse or a centrally-heated home suits them perfectly. If the temperature stays above 12ºC, red spider mites can breed all year round.


Spider mite symptoms

Spider mites are easy to spot on green house plants and house plants. You will see fine webbing on the leaves and stems, while mottling is visible on the upper surface of leaves. Using a magnifying glass, look for mites and eggs on the undersides of leaves. The plants will lack vigour and may eventually die.

Find spider mite on

Spider mites are typically found on house plants and greenhouse plants, but you may also spot them outdoors on fuchsias, runner beans, busy lizzies and grape vines.

How to kill spider mite

Misting plants in a greenhouse to increase humidity
Misting plants in a greenhouse to increase humidity

The best way to tackle spider mites is to stop it reproducing. They thrive in hot, dry conditions, so improve air circulation and boost levels of humidity by misting plants with tepid water and standing bowls of water on the benches between plants. Damping down the floor of your greenhouse with water will also help increase humidity.

When daytime temperatures in the greenhouse hover steadily around 21ºC, you can try releasing the predatory mite, Phytoseiulus persimilis on to your plants. This is the most common biological pest control for red spider mite in greenhouses and the home. The predatory mites feed on spider mites at all stages of their lifecycle, including eggs. This quickly reduces the spider mite population and therefore plant damage.

If temperatures remain lower than 15ºC (the minimum temperature at which Phytoseiulus persimilis can survive), try using sprays containing fatty acids or plant oils, instead.