Here are some recipes to make your own insecticidal soap. It is predominantly used in sprays to treat affected plants. There are different methods to make it. Simple sprays can contain mixes of water and liquid soap. Slightly complicated ones are those where you first boil a mix of onions, horseradish, garlic, ginger, hot peppers, cayenne and rhubarb leaves and then add this broth after straining it to soap spray. All of these ingredients are known and proven insect repellents. It is imperative that you use this concoction as soon as possible or it will start to rot. Another very effective method is to use the extract of leaves of the Neem tree in the same way. Simple organic sprays with just garlic can ward off bigger pests.
