1. Soapy water (NOT detergent). Try to find one based on caustic potash, rather than caustic soda and mix well with water until frothy (you’ll need more soap in hard water areas). For aphids and other soft-shelled insects
2. Oil sprays suffocate insects. Boil 1 kg soap with 8L of oil, stirring until dissolved. Dilute 1:20 with water just before use. Spray on cool days only.
3. Tomato leaf spray (very poisonous). Cover leaves with water, boil and cool. Use immediately as a general insecticide.
4. Pyrethrum spray. Pick almost-open flowers of Tanacetum cinerariifolium and dry in a cool place. Cover a few tablespoons of flowers with cheap sherry, steep overnight and mix with a litre of hot soapy water. Cool and use within a few days as a general insecticide. Store in a dark place.
5. Wormwood spray. Infuse leaves in boiling water and leave for a few hours. Dilute 1:4 and use for sap-sucking insects.
6. Chilli spray – equal volumes chilli and water blended and sprayed fresh onto caterpillars. (Prevent contact with eyes and skin.)
7. Lapsang Souchong tea – a strong brew (1 tbspn in a pot) deters possums from nipping rose tips
Many other materials can be used to make insect sprays. Depending on what you have available, try -quassia, garlic, marigolds, melaleuca, parsnips, turnips, eucalyptus, larkspur, elder, white cedar (Melia azaderach) or rhubarb (Please note: larkspur, elder (except for ripe berries) white cedar and rhubarb leaves are all highly toxic to humans.)