Organic Controls for Garden Pests

Calendar for Pest Control

January and February

Due to low light levels, not many pests will be out and about at this time. A good time to clean up indoors. In a conservatory use soft soap to wash off pests and if you see any aphids or whiteflies pinch them between your fingers. Every one you kill now will be several hundred fewer at the end of the Summer! You could also try hanging up sticky traps which will kill the odd flying pest and will help monitor the potential problems.

March and April

Be very vigilant from now on. Treating pest outbreaks early is the key to success. Aphidius and Encarsia can be introduced into warm conservatories from March, to control early outbreaks of Aphids (greenfly), and Whitefly respectively. Outdoors: Slug control can be applied where soil temperatures are above 5C , now and on through the Summer into Autumn. Vine Weevil nematodes should be applied from March - end of May where soil temperatures reach 5C .
In the cold greenhouse keep an eye out for sciarid fly or thrips. If you think there may be larvae around then consider either watering on nematodes or using mites - Hypoaspis or Amblyseius

May and June

If Whitefly infestation is bad in your greenhouse or conservatory, make a second introduction of Encarsia. Keep checking for the first signs of Red Spider Mite which generally appears during May and introduce Phytoseiulus without delay when you find any. The Mealybug control, Cryptolaemus , should be applied as temperatures rise from mid-May.

June and July

Make more applications of biological controls if pest populations build up. Damping down plants and floors will reduce excessive temperatures and increase humidity to help the beneficial insects work better. Numbers of beneficials should be building up nicely now, to give good control by the end of the season, but last top-ups can be introduced now to boost numbers.
Don't wait until caterpillars make lacework of your cabbages before taking action. Unfortunately the bacteriological control Bacillus thuringiensis is only available if you are a licensed professional grower, but this year you can try a caterpillar nematode killer

August and September

Apply Chafer Grub control to lawns during August and early September when the young larvae are active. The second Vine Weevil control can be applied from mid-August to November to catch any grubs which plan to spend the Winter in your pots or garden.
If you are still being troubled with thrips, spider mite or whitefly then give them one more treatment. These controls will probably not last the winter (unless temperature and light levels are high) but it will help keep the pest populations down for the end of this year.


When removing tomatoes or other plants which are harbouring pests, be careful to dispose of them in a way which does not pass the pests on to remaining plants. Burning on a flaming fire is probably best, but trapping in a sealed bag is also effective.
Clean up as much as possible, removing dead leaves and wiping away any sooty mould on leaves. Spray localised pest outbreaks with Soft Soap spray and wipe off scales and mealybugs wherever seen.