I was given two recipes for making my own insecticidal soap using “Dawn” dishwashing liquid and “Fels-Naptha” soap.

dawn dishwashing soap.jpg

I was given two recipes for making my own insecticidal soap using “Dawn” dishwashing liquid and “Fels-Naptha” soap. Will these really work?

Insecticidal soap is a very safe and effective alternative to conventional insecticides in garden situations. It is used mainly for soft-bodied pests like aphids, thrips, scale insect crawlers and spider mites.

Do not jump to the conclusion that you can substitute household soaps, or homemade soaps, for genuine insecticidal soap. Doing so will damage your plants and probably won't be very effective. Dishwashing liquids and laundry detergents are designed to dissolve grease, not kill insects and mites. Commercially prepared insecticidal soaps have been through more rigorous testing for efficacy and plant safety than household detergents and soaps, so we know how they’ll perform in the garden. They are clearly labeled for your horticultural use as insecticides, not for cleaning your dishes.

“Hey, soap is soap,” you might be thinking. But, it really isn’t. The chemical properties of soap can result in the soap being an insecticide (kills insects) or a herbicide (kills weeds).

Other factors include the various dyes and perfumes that are added to kitchen soaps. These additives are often switched or changed to please the retail customer. So even if you do find one that works, how long before the formula is “new and improved” or changed without warning? Plus, these soaps are not organic!
Should you want to try your recipe, here are a few tips to minimize plant injury.
1. Detergent soaps are reputed to be more damaging to plants if used excessively. If you choose to use a dish detergent, make sure to rinse your plants within an hour of applying the insecticide.
2. Do not spray plants on very hot or humid days, as the plant will be more prone to burning.
3. Always test a small area of the plant that is not too visible before applying and insecticide. Some species, especially those with lightly colored foliage, are more likely to be burned by soaps.
Insecticidal soaps can be a great tool in a pest management program. They kill a wide range of pests, are relatively inexpensive, are compatible with beneficial insects and don’t have resistance issues. In other words, when used properly, these soaps can really help you clean up your garden of unwanted pests.