Please note that insecticidal soaps have "POTASSIUM salts of fatty acids"....Thus, if you want to make insecticidal soap from scratch, you need to use soaps like Murphy Oil Soap, Lysol Brand Cleaner Original Scent (Concentrate) which contain potassium hydroxide,
You only need to use a 1% dilution with any clean NON chlorinated water. NO chlorine!!
NOTE:
DO NOT use soaps that contain LYE!! (sodium hydroxide).
DO NOT use detergents such as liquid dish soap!!
Other products that contain potassium-hydroxide http://www.potassium-hydroxide.com/productcontaining.htm
Unlike soap which is organic, detergents are chemical cleaners and are toxic to most plants.
There are now major brand garden safe insecticidal soap that are very good to kill the aphids on contact. I think the best for killing aphids is lady bug larvae. I see these larvae making aphids on the run.
Store bought brands of insecticidal soap certainly costs more than homemade concoctions, but a little goes a long way and it's formulated to be hard on bugs and easy on plants. That's the primary problem with homemade solutions, they can strip the waxy coating right off plants resulting in damage.
There are animal and plant based formulations available.
Application
Spray Bottle or Garden Sprayer
The reason that soap kills insects effectively is the fatty acids from the animal fats the soap is made from which is why you need real soap and not a detergent. Those fatty acids dissolve the target insects exoskeleton so they dehydrate.
It is therefore important to spray the insecticide directly on pests, saturating them thoroughly. Spray every bit of the plant with the soap insecticide, paying special attention to intersections and the undersides of leaves where pests hide and lay eggs. Once the soap residue has dried on the plant, it will lose its insect-killing properties. Rinse off the film and reapply about once a week until no signs of infestation are visible. Soap insecticides only kill small, soft-bodied insects like aphids, spider mites, white flies, mealybugs, and immature scales. They will also destroy all eggs, including those of moths, flies, and beetles, as well as very small larvae. Larger pests (Japanese beetles, maggots, and caterpillars, for example) will be unaffected. For this reason, adding an all-purpose repellant to the mixture may be beneficial. Otherwise, you may have to resort to commercial products to eradicate these pests.
Do NOT use garlic as this may burn the leaves!! Garlic, however, will help keep deer and rabbit’s at bay.
