Neem Oil - A Natural Way to Treat Plant Infestations

Neem oil is an all natural oil from the seeds of the neem tree (Azadirachta Indica) and is way to protect and treat both houseplants and farm crops from insect infestations through a compound called azadirachtin that disrupts the growth and reproduction cycles of the adult insects (some studies show up to 90% of the pests reproductive cycles are affected). In younger insects it may be able to kill them by suffocation with the oil covering their breathing openings, but this is not likely to happen with adults. And neem oil works as a feeding deterrent helping to stop insects from eating the plants.

While azadirachtin is the main compound, there are more than 100 biologically active ones. Some of the plant insect infestations that neem oil can be helpful with include:

• Aphids

• Beetle Larvae

• Caterpillars

• Fungus Gnats

• Lacebugs

• Leafminers

• Mealybugs

• Scales

• Spider Mites

• Thrips

• Whiteflies

Neem oil is also able to coat the spores that fungus use to reproduce and sink into the plant’s tissue, helping to stop the spread before fungus like powdery mildew, blackspot, and rust can impact your houseplants and outdoor plants. Unfortunately if the plant is already impacted by fungus, the neem oil will not help treat the issue as it only helps to stop the reproductive cycles of the fungus. 

Fun fact: Neem oil has been seen to destroy the Desert Locust’s antennae when applied, including to the abdomen.

One of the reasons eco-cautious plant parents and gardeners like neem oil is that it is practically non-toxic to birds, mammals, bees, and plants, so you can have pollinator gardens and not have to worry about your backyard visitors if you have a bird feeder. However you should not use neem oil if you have fish or aquatic animals as it is moderately toxic to them.

If you have a current issue, or want to take proactive measures to help prevent an infestation, here’s how to mix, treat, and use neem oil on your house and outdoor plants.

There are two main ways to use neem oil on plants as a preventative way to treat and stop infestations from insects and mold including applying a mixture to the leaves and stems, or by placing it in the soil or potting mix. When applied topically to plants it can suffocate the younger insects and helps stop the reproductive cycles of adults and molds. 

When used via the roots in your watering cycles it can impact some of the insects that suck sap like Aphids and Whiteflies from the leaves and stems to help prevent them from breeding. The added benefit of stopping the sap sucking insects is they won’t be able to produce honeydew which traps the mold and allows black sooty mold and other fungus infestations to harm the plant.

Pro-tip: Always wear gloves when using neem oil as it could be an irritant to human skin.

To make your neem oil mix you’ll need:

• A 1 liter spray bottle

• Teaspoons

• Neem oil extract

• Mild soap or detergent

• Water

The steps to treat plants with neem oil are:

1. Mix 1 and ½ teaspoons of neem oil extract with 1 teaspoon of a mild soap or detergent and combine with 1 liter of water.

2. Shake or stir well.

3. In the late afternoon or evening, spray the leaves and stems of your plant (on all sides including the top and the bottom of the leaf) with a thin and even layer of the mixture.

4. Let the neem oil dry naturally.

Pro-tip: When applying neem oil to a leaf, do it in the evening so the oil has time to dry up and does not cause leaf burn or sun damage when the sun’s light can be amplified.

When you add neem oil to your watering schedule every once in a while (monthly or every three months should be enough), the plants spread it through their vascular systems to help prevent infestations from insects that bite through and suck the sap.

Pro-tip: Test the mixture on a single plant or two plants and watch for any signs of distress or damage. If the plants show no signs of being unhealthy, use the mixture on the rest. If the plants are unhealthy, your mixture may be too strong.

You will need:

• 1 gallon container

• 1 tablespoon

• Neem oil extract

• Mild soap or detergent

• Water

The steps to follow are:

1. Mix a few drops of a mild dish soap into a gallon of warm water (not hot or cold).

2. Add in two tablespoons of neem oil extract into the water and soap mixture.

3. Water your houseplants like normal, for outdoor plants water in the early morning or late evening so the plants can absorb the mixture without the sun drying it out.

Neem oil is one of the best all-natural ways to help prevent and treat specific insects and some mold infestations. It works for both houseplants and garden plants, and can be one of your best kept secrets to keeping your plants healthy.