6 other natural pesticides
Slug traps can be bought from garden centres or online
Beer
Don’t throw out the dregs of your Friday night in – cheap beer is one of the best slugicides there is. Pour 5cm beer into a family-sized yoghurt pot and bury with the lip above ground to keep beetles out. Slugs adore yeasty beer, crawl in and meet a boozy end.
Treats Slugs
Tomato leaves Elizabethans called newly arrived tomatoes ‘poison apples’, but it wasn’t the fruits they needed to worry about – tomato leaves carry toxic alkaloids that deter, and can kill, sap-sucking insects. Chop 500g leaves and steep overnight in a litre of water, Strain and spray. Treats Aphids, red spider mite
Milk
Studies show that cow’s milk, when it reacts to sunlight, is effective against mildew. Mix with water in a 50-50 ratio (use skimmed or semiskimmed as the fat in milk can lead to odours) and spray weekly on the leaves, early in the morning. Wait 30 minutes for the liquid to dry, then wipe off any excess. Treats Courgettes, grapevines, tomatoes
Rhubarb leaves
Rhubarb leaves are full of oxalic acid, toxic to us and sap-sucking pests (and beneficial insects, so use with care). Boil 500g rhubarb leaves in a litre of water for half an hour, strain and spray
(on ornamental plants only). Treats Aphids, red spider mite, whitefly
Citrus peel
If you’ve watched cats wince and back away when you peel oranges you’ll know they detest citrus. Roughly chop peel in a blender, then scatter alongside plants to keep cats away. Hollowed-out orange and grapefruit halves attract slugs, too – place upside down on the ground, wait for slugs to enter, then collect and dispose of them.
Treats Cats, slugs
Soap
Sap-sucking pests breathe through holes in their backs so will suffocate if coated in a film of soap. Stir a tablespoon of liquid soap into a litre of warm water, cool, then spray. Use as a last resort as it kills beneficial insects too. Treats Aphids, blackfly, caterpillars, scale insects, whitefly
Mexican marigold (Tagetes minuta) This 1.5m tall annual emits powerful chemicals from its roots that suppress potential competitors – including perennial weeds such as bindweed and ground elder. Sow under cover and plant out once growing on strongly. It’ll also stop nearby garden plants growing, though, so use on its own for clearing problem patches before planting the following year. Don’t use alongside beneficial nematodes.
Mulching over cardboard Shear off top growth of perennial weeds including couch grass, ground elder or bindweed, then cover the ground with two or three layers of cardboard. Spread a 10-15cm deep mulch of compost over the top and plant. You may need to repeat the treatment for a few years, but eventually the weeds do give up.