How to Use Organic Pesticides


When you decide to grow your own vegetables and fruits, you'll be learning about nature, getting some fresh, good-tasting foods right in your own backyard, and perhaps saving a bit of money. The health benefits of fresh produce are undisputed, so you probably will want to use more natural methods to control the insects and other creatures that like to eat the fruits of your labor. From sprinkling iron phosphate granules for snails to spraying insecticidal soap on aphids, organic pesticides are safe and effective.

Using Organic Pesticides

Step 1

Control aphids and other soft-bodied sucking insects with a spray of insecticidal soap. You can purchase ready-made insecticidal soap at garden supply stores or make your own: Mix 1 tbsp. of a mild dishwashing detergent with 1 qt. of water in a plastic spray bottle. Spray your plants as soon as you notice curling or yellowing leaves and discover small green insects, often on the undersides of the leaves. Be sure to thoroughly saturate the plant and repeat spraying every other day until all of the insects are gone. Spray after the area is shaded to prevent sunburned leaves.

Step 2

Treat scale insects, small armored insects that suck the liquid from plants, with a combination of insecticidal soap and canola oil. Mix one tablespoon of mild dishwashing detergent and one tablespoon of canola oil with one quart of water in a plastic spray bottle. The soap will kill young, soft-bodied scale insects and the oil will smother the older, armored insects. Spray every other day until you see no more insects. You can also hand pick scale and squash them.

Step 3

Sprinkle iron phosphate granules around your planting beds to kill snails and slugs. This product is marketed under the brand name "Sluggo." Iron phosphate is a natural soil ingredient and is toxic to snails and slugs. Another helpful product for these destructive creatures is diatomaceous earth. This substance comes from fossilized aquatic plants and is a siliceous mineral that has very sharp edges on its tiny particles. Snails and slugs simply cannot crawl over it. Scatter a ½ inch thick layer of diatomaceous earth around the borders of your susceptible garden beds. Diatomaceous earth also deters sawflies, flea beetles, twig borers, coddling moths, cockroaches, earwigs and ants.

Step 4

Dust plants for caterpillars, grubs and worms with Bacillus thuringiensis (Bt). This product is a natural bacterium that lives in soil and is toxic to many crawling larvae that can decimate a small plant in no time. Large worms, such as the tomato hornworm, might not die after you dust your plant with Bt, so if you can find them, hand pick and squash larger worms.

Step 5

Apply a ring of Tree Tanglefoot around the lower stalk of plants to keep ants away. Although ants do not harm the plant, they bring insects such as aphids and scale so they can feed off their sweet excretions. The insects that ants "farm" do harm your plants, so by keeping ants away, you can proactively prevent other harmful insects.

Tips and Warnings

  • Always follow label instructions for pest control products, even if they are organic.

Things You'll Need

  • Insecticidal soap (purchased)
  • Mild dishwashing liquid
  • Water
  • Spray bottle
  • Canola oil
  • Iron phosphate granules
  • Diatomaceous earth
  • Bacillus thuringiensis (Bt)
  • Tree Tanglefoot


  • Organic Crop Improvement Association

Who Can Help

  • Pest Products: Sluggo Slug and Snail Bait
  • GH Organics: Diatomaceous Earth
  • Tanglefoot: Tree Tanglefoot Pest Barrier
Keywords: organic gardening, pesticides natural, vegetables snails, aphids scale

About this Author

Barbara Fahs lives on Hawaii island, where she has created Hi'iaka's Healing Herb Garden. Fahs wrote "Super Simple Guide to Creating Hawaiian Gardens," and has been a professional writer since 1984. She contributes to Big Island Weekly, Ke Ola magazine, GardenGuides and eHow. She earned her B.A. at UCSB and her M.A. from San Jose State University.