It happens to the greenest-thumbed gardeners: you're admiring the juicy veggies or beautiful flowers you worked so hard to grow—and notice bugs chowing down on your precious plants/ We invest lots of time, love, and care into our gardens, and when they're threatened, we want to want to protect them.
Organic pesticides like neem oil can help control unwanted insects and fungal diseases on your plants. Here's how to use neem oil as a natural insecticide in your garden.
What Is Neem Oil?
Neem oil is derived from the seeds of the neem tree, which is native to parts of South Asia. There, it's used as a traditional medicine as well as for pest control. Neem is also used in personal care products like soap, makeup, and toothpaste.
The primary pest-repelling ingredient in neem oil is a substance called azadirachtin, which is typically extracted from the raw oil and used as a commercial pesticide. A product called clarified hydrophobic neem oil is what's left over. This is the active ingredient in ready-to-use sprays that typically available at hardware stores, plant nurseries, and garden centers.
When to Use Neem Oil in Your Garden
Use neem oil to control immature insects like beetles, aphids, mealybugs, caterpillars, thrips, whiteflies, leaf hoppers, and leaf miners. Neem works by covering the insects so that they can't breathe. However, the effect is not immediate, so you'll probably need to reapply to control the problem.
Be sure to identify insects properly, as neem can harm beneficial insects. Paying attention to where the pests are in their life cycle is also important. Neem won't kill adult insects, so you must apply it during their immature phases for it to be effective.
You can also use neem oil to control—but not eliminate—fungal issues such as powdery mildew. Neem will keep fungus from spreading and reproducing, but it won't reverse the issue.
Precautions to Take When Using Neem Oil
Neem oil is considered organic and is designated as GRAS (generally recognized as safe) by the U.S. Food and Drug administration. However, it's still a pesticide and should be handled carefully. Exposure to neem oil can cause irritation to the eyes and skin. If ingested, azadirachtin can irritate the stomach.
Because neem can harm aquatic animals like fish, it's best to avoid using it near ponds, lakes, or other bodies of water. It can also harm bees, butterflies, and other pollinators, so refrain from applying it while those good bugs are in the area.
If possible, explore pesticide-free methods of pest control such as removing insects by hand or spraying them off of your plants with a hose before using neem. Be sure to follow package instructions when using neem oil in your garden. Limit your exposure to the product and wear personal protective equipment like gloves, a mask, and eye protection when applying it to plants.
How to Use Neem Oil As an Organic Insecticide
Neem oil is safe to use on herbs, fruits, vegetables, and ornamental plants in your garden. However, neem oil can damage plants that are already stressed due to drought, extreme heat, or recent transplanting, so it's best to use on healthy, mature plants.
You can purchase ready-to-use neem oil spray and apply it to plants according to package directions, or purchase cold-pressed neem oil and mix the spray yourself. If possible, apply neem to a small area of the plant first and watch for any adverse affects. If there are no issues after a day or so, you can apply it to the entire plant.
What You'll Need
- Cold-pressed neem oil
- Protective equipment such as gardening gloves, eye protection, and face mask
- Spray bottle
- Mild dish soap
Step 1: Mix Soap and Water in a Spray Bottle
Fill your spray bottle until nearly full with tepid water. Mix in the mild dish soap using the ratio of one teaspoon of soap to one gallon of water. The soap will will emulsify the water and oil together. For a one-quart spray bottle, add a quarter-teaspoon to half-teaspoon of soap. Shake a few times to combine.
Step 2: Add Neem Oil to the Soapy Water Mixture
Slowly add a small amount of neem to the soapy water. For a one-quart spray bottle, add a half-teaspoon of neem oil. Shake the sprayer until the mixture is thoroughly combined.
Step 3: Test the Neem Oil Spray
Spray a small area of a healthy, mature plant. The next day, check the area. If there is no damage, you can apply the neem oil spray to leaves of your plants affected by pests.
Step 4: Apply Neem Spray to Plant Surfaces
Spray affected plant surfaces well with neem oil. Be sure to spray the tops and undersides of leaves so they are completely covered.
Step 5: Reapply as Needed
Keep an eye on your plants to gauge the effect of the neem oil. You may need to reapply every one to two weeks to reduce pest activity.