Consumers often confuse all-natural and non-toxic but there’s a critical difference when it comes to organic gardening.

Substances like pyrethrum, nicotine sulfate and rotenone are all natural, but they’re also toxic. They are a significant improvement over chemical pesticides because they break down much more quickly in the environment. However, they are still contact poisons that directly kill insects, including beneficial insects. Pyrethrums, even the all-natural products made from a species of chrysanthemums, are particularly harmful to reptiles and amphibians like the lizards, frogs and tadpoles that provide natural insect control.

Neem, on the other hand, is a non-toxic substance that actually increases earthworm populations and shows little or no toxicity to beneficial insects like bees and butterflies. Over time, gardening organically with non-toxic substances like neem helps boost soil microbes, improving the health of the soil – and the health of your plants.

Several neem products are labeled to treat insect pests or as fungicides, but they’re processed neem oil that may actually contain a very small percentage of active ingredients -- not the all-natural raw material that has been used in tropical countries around the world for centuries. To date, no company has succeeded in obtaining EPA approval for an all-natural neem product, although Organix South is working with its vendors to earn that recognition for its natural neem oil.

The Secret is the Smell!

The aromatic profile of neem oil (sometimes described as strong nutty, garlic or sulphur) is a major reason neem is so effective. Plants are intelligent in their “formulation strategies” and intentionally create constituents that ward off unwanted predators such as insects, fungal and microbial infections. In fact, neem originally came to the attention of the western world in 1956 when a German entomologist noticed that neem trees were the only green plants remaining after a swarm of locusts swept through Egypt.

A more recent report from the University of Connecticut notes that the azadirachtin in neem affects more than 60 pests including aphids, beetles, caterpillars, lace bugs, leafhoppers, mealybugs, thrips and whiteflies. Depending upon the insect, the azadirachtin in neem can act as a repellant or feeding deterrent, as a growth regulator that restricts larva from developing into adults, or it may interrupt their mating and sexual communications.

In most cases, you won’t see the immediate knock-down that happens with more toxic products, but working with your ecosystem instead of against it provides long-term benefits. An early report on neem indicates that when neem leaves and seed kernels are incorporated into potting soil, the number of young worms produced increased 25 percent. The same report shows that the average weight of worms increased in neem-treated fields. Other reports indicate that it is less likely to harm bees and butterflies because it works primarily on insects that are eating plants. (It does not, however, differentiate between noxious caterpillars and those that become beautiful butterflies, so avoid using neem on larval butterfly plants like milkweed or parsley.)

Neem also minimizes damage to the beneficial microbes that live in healthy soil. According to the Organic Trade Association, organic soil management improves soil structure by increasing microbial activity. Beneficial soil microbes break down organic matter into substances plants can easily absorb and help protect plants from nematodes and harmful fungi.

Raw neem oil is highly concentrated and is used at a rate of about 1 teaspoon per quart or a tablespoon per gallon of warm water with a small amount of environmentally friendly dish soap to emulsify the oil and water combination.

Learn more!

Although no all-natural neem products are labeled to treat insects, researchers in universities around the world are documenting its impact.

To learn more, visit:

The National Academy Press, “NEEM: A Tree for Solving Global Problems,” 1992. Full text available online at no charge.

The Extension Toxicology Network’s detailed information on using neem as a pesticide which indicates that it is “relatively non-toxic” and “relatively harmless” to beneficial insects.

University of Connecticut report on using neem in an integrated pest management program, including modes of action.