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Debugging the Garden with Natural Pesticides


Debugging the Garden with Natural Pesticides

Garden PestsMany people hear the words "bugs" or "insects" and imagine horrible creatures preying on their garden. The truth is that all insects serve a purpose in the ecosystem. And although I'm hard pressed to come up with a reason nature included the tick among her creatures, I'm guessing some animal, insect or bird finds them delicious.

The goal with any organic garden is to nurture the beneficial insects, minimize the harmful ones, and attract helpers such as birds to the garden who naturally eat insects and larvae, thus reducing their numbers as nature intended. With this in mind, let's look at two areas of natural pesticides: using plants themselves as pesticides and sprays for difficult conditions.

Plants as Pesticides

Gardeners discovered through much trial and error that plants worked well as natural insecticides. Some plants exude chemicals or scents that repel various insects. Others 'trap' insects or attract them, which keeps the bad bugs from attacking desirable plants by luring them to others.  

Examples include:
  • Marigolds: By far the most commonly cited natural pesticide, marigolds exude a strong odor created by chemicals that repel pests. Plan them liberally throughout the vegetable and flower garden. The seeds are inexpensive and grow in almost any kind of soil. They'll also reseed easily, or you can collect seeds in the fall to store them for later.
  • Nasturtiums: Nasturtium flowers act as trap plants, luring certain moths and beetles away from vegetables in the cabbage family. The insects munch on the nasturtium flowers and leaves while leaving the vegetables along.

Organic Insecticides

Organic insecticides rely upon plant compounds or essential oils to repel or protect insects. Commercial sprays marketed as organic must list the major ingredients; check the label for proper use.

Common organic insecticide ingredients include:
  • Neem oil: The neem tree hails from India. Its oils repel many insects, including Japanese beetles. It also has the added benefit of acting as a fungicide. Neem-based sprays provide excellent beetle and black spot control on roses, for example. Neem-based pesticides are available in spray-on bottles and concentrated oils.
  • Lemon oil: Some organic pesticides use lemon or another citrus essential oil to repel various insects.
  • Diatomaceous earth: Diatomaceous earth is a special product mined from ancient mineral sources. Diatoms lived millions of years ago, and their shells and fossilized remains are crushed into a powder.  Diatomaceous earth sprinkled around hostas and garden vegetables kills slugs, snails and soft-bodied insects.
  • Insecticidal soap: Insecticidal soap combines fatty acids and soap into a liquid. It is nontoxic. You must apply it while insects are active; once it dries, it's not particularly useful.
  • BT or Bacillus Thuringiensis: This naturally occurring bacterium is safe to use around animals and people, but it acts like a stomach poison on insects. Follow label directions for appropriate use. It is slow acting but does work.

There are other organic pesticides, but some cause more harm than good. Pyrethrin is a good example. Although it is derived from the chrysanthemum plant (which sounds like it should be safe) it's deadly to honey bees. It acts like a strong broad spectrum insecticide and should only be used in worst case scenarios.

Can You Live with Bugs?

Before reaching for my own arsenal of organic sprays and control methods, I always ask myself, "Can I live with this creature?"  Most of the time, the answer is yes. I'm not growing my organic vegetables, herbs and flowers for sale; they're for my pleasure and taste, and so what if my lettuce leaf has a hole in it or I lose a tomato or two?

I do my best to nurture wildlife around the garden that keeps the bad bugs in check. Bluebird houses placed around the farm and on a fence post next to the vegetable garden encourage these lively birds to nest nearby, and each one eats many insects in one day. When they're raising a little family, they eat even more! Bird baths and trees attractive to bird also encourage more insect-eaters to visit the garden.

Keep the garden clean. Insects often lay eggs among fallen leaves and decaying plants. By sweeping or raking up spent plants at the end of the growing season, you'll also remove insect eggs for potentially harmful bugs.

About the Author

Jeanne Grunert is a writer and marketing consultant who moved from New York City to a 17 acre organic farm in rural Virginia. She writes about gardening, health and raw foods for many publications, and her gardening book, Get Your Hands Dirty – A Beginner's Guide to Gardening is available in paperback and as an E book on or, the publisher's website. Her new book, Diet from the Garden, will be available this summer and focuses on how to change to a fresh, living foods diet. For more about Jeanne, her books and writing, please visit

These statements have not been evaluated by the food and drug administration. The preceding information and/or products are for educational purposes only and are not meant to diagnose, prescribe, or treat illness. Please consult your doctor before making any changes or before starting ANY exercise or nutritional supplement program or before using this information or any product during pregnancy or if you have a serious medical condition.

Written by:  Jeanne Grunert
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