Last year we had real problems with black fly infesting everything at the allotment. We had been using an organic soap based spray but it was not cheap. After a bit of research, we made some chilli spray. I wrote about some of these ideas earlier and I have recent got a couple going.
The first is chilli with a hint of garlic – the idea is that insects and slugs don’t like hot spicy food. We had a big bag of chilli de arbol in the cupboard and these are hot dried Mexican chillies. Its not a complex process to make the concentrate. I have a small electric grinder that makes things very easy – put a handful of these hot little numbers in and blitz to a powder. Mix them up in the jar with oil, crushed garlic and a couple of drops of washing up liquid with some water. Shake and leave in the sun.
The second one is a new one – coffee and herbs. If you look at woody herbs – lavender, rosemary and thyme etc – the leaves don’t get eaten. The caffeine in the coffee is a deterrent for lots of insects apparently. So the same idea, grind up the herbs with oil and then add coffee, a few drops of washing up liquid and water.
These are now sitting in the greenhouse for a week or three, then I will strain and store in old vinegar bottles.