How to use neem oil

Story and Photography by Brittany May

Neem oil is created by pressing the seeds and fruits of the neem tree (Azadirachta indica), which is native to South Asia and India. Pure neem oil has been used for centuries for its medicinal properties. It is also a major ingredient in many soaps and cosmetics around the world.

It was eventually discovered that the active ingredient in neem oil, azadirachtin, would deter insects in several different ways. Spraying the oil on the plants stops insects from feeding on them. There are properties in neem oil that seem to disrupt the hormones of many insects, preventing them from reproducing, or proceed to their next life stage.

It is suggested that neem oil has successfully repelled more than 200 insects such as ants, aphids, bedbugs, beetles, caterpillars, gnats, Japanese beetles, mites, mosquitoes, moth larvae, roaches, snails, termites, and whiteflies.

In addition, it has proven to be a natural fungicide – effective against both fungal diseases and bacterial diseases such as black spot, leaf spot, fire blight, rust, wilt, powdery mildew, and more. 

One major benefit of using neem oil is the fact that it is virtually non-toxic. Birds, mammals, bees, earthworms, and plants are not harmed by using this oil. It appears to be toxic to fish, but it is important to remember that the oil must be ingested for it to work. Therefore, insects that eat the leaves will be affected, and likewise fish that take in water neem oil has been sprayed on may be affected.

In the United States, neem trees can be grown in Zones 10-12, and can reach a height of 75 feet. Living for approximately 200 years, the easiest way to grow this tree is to plant seeds or find a root cutting. Once your tree is established, you can use the seeds or the leaves to create your own neem oil products. 

If you don’t live in Zones 10-12, you can purchase neem oil at garden centers or online. Purchasing cold-pressed neem oil will get you the most natural version of neem oil without any additives. This will be best for you, your garden, your pets, and the local beneficial insect population. It is important to use the correct concentration that is listed on the label. Incorrect application could potentially harm some insects.

Neem oil is also a great way to protect your hummingbird feeders from ants. Sometimes, it seems like ants manage to find ways around everything. Bafflers and vegetable oil just don’t seem to work. However, a quick wipe with neem oil deters the ants, while remaining non-toxic to the hummingbirds themselves.

Due to its short half-life, the major chemical synthesized from cold-pressed neem oil, azadirachtin, degrades very quickly once exposed to sunlight and/or water. It is important to note that as with all other pesticides and insecticides, this will have to be reapplied, at least after every rain, but it is recommended to re-apply at least every seven to 14 days for maximum effectiveness against pests and fungus.

Another major benefit of using neem oil is the fact that it is completely safe to use all the way until you harvest your garden. Applying any sort of pesticide to the food you are going to be consuming is always a worry, especially if you are allowing your animals to consume some of the produce. Neem oil provides a safe, non-toxic alternative that is easily rinsed off any produce.



Make Your Own!

To make your own neem oil, you can do one of two different things. 

1. Grind the seeds to create a mash, then place this in a bowl, cover with water, and allow the mixture to sit for at least a couple of days. Strain off the liquid, pour through cheesecloth, and fill a spray bottle. (You can also add a teaspoon of dishwashing detergent to the mixture to help adhere the oil to the leaves of your plants.)

2. Collect a large amount of the leaves, place in bucket, and cover with several inches of water. Allow this mixture to sit for at least a week. Strain off the liquid, and fill a spray bottle. (You can also add a teaspoon of dishwashing detergent to the mixture to help adhere the oil to the leaves of your plants.)

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