Homemade pesticides and repellents can be safer than synthetic substances in terms of undesirable side effects. Nevertheless, they should be treated with respect. Wash the vegetables before eating them, and use the sprays in the spring if possible to avoid unnecessary ecological damage. Here are some of the concoctions my fellow gardeners and I have shared with each other over the years.
Recipes for homemade pesticides that are safer for your garden
Biodynamic spray: mix powdered clay and organic insecticide such as rotenone with enough water to make a thin fluid. Spray on fruit trees in early spring before leaves appear to suffocate ace of insect pests.
Buttermilk and flower spray: mix 1/2 cup buttermilk and 4 cups wheat flour with 5 gallons of water. This one kills spider mites and other mites by suffocation.
Cedar extract: boil 1/4 pound cedar chips or dust in 1 gallon of water for two hours. Then strain into lit the liquid with three parts water. Spray this on plants to repel Mexican bean beetles and other troublesome beetles.
Garlic and hot pepper spray: steep 1/2 teaspoon each of garlic and crushed hot peppers in 1 gallon of water for 10 to 24 hours. Useful on woody plants or dilute 25% for annuals and vegetables. The spray repels many sucking and chewing insects.
Glue mixture: dissolve 1/4 pound of fish or animal glue in 1 gallon of warm water. Spray trees and bushes to trap and kill aphids, spider mites, and scale insects (it removes pests from trees when it flakes off on drying.)
Green soap spray: mix 1 cup of green soap tincture with 3 gallons of water. This will kill non-furry caterpillars on contact. Green soap is available in drugstores. Laundry soap can be used instead in the ratio of 1/2 cup of soap to 1 gallon of hot water. If used on non-woody plants, rinse off with clear water immediately after applying.
Quassia spray: boil 1/4 pound quassia chips in 1 gallon of water for two hours, stirring liquid, and mix with three to five parts water. The spray poisons aphids and caterpillars but is harmless to ladybugs and bees.
In addition to these homemade pesticides, organic sprays can also be made from infusions of larkspur seeds, rhubarb leaves, or tobacco. Such sprays are nonpersistent and are effective against a variety of insect pests–larkspur against aphids, thrips, and several species of chewing insects.
Rhubarb also works well against aphids. Tobacco works well against a wide assortment of soft-bodied insects. However, these preparations are pretty much safe but still poisonous to humans and animals. If you do use them, be sure to wash the produce thoroughly before eating it.