12 essential oils for plants that treat pests, fungus, and more

• marquis matson
• Apr 22, 2023
• No Comments

Plant essential oils are natural substances that can be used in holistic aromatherapy, in natural beauty products, or…

…to improve the health of indoor and outdoor plants.

We know some essential oils for their ability to help with common gardening issues, such as controlling pests and improving plant growth.

There are many essential oils and it is important to choose the right one for the task at hand. Just like when working with a pure essential oil in beauty products and with aromatherapy, a little goes a long way. Too much and you can cause more harm than good.

Before using essential oils for anything on your plants, read through this entire post, including how to administer the essential oil. It’s important to use essential oils cautiously so that you don’t burn your plants.

For now, let’s dive into the science behind essential oils for plants, and find out which are the best essential oils for your indoor plants.

Best essential oils for plants and gardening

Plant essential oils are made with steam distillation, which extracts the active ingredients from the plant material. The distilled oil is a highly concentrated form of medicine or, when too much is used, poison.

Essential oils have been studied for years and continue to be studied because of their medicinal properties and for use as pesticides and herbicides in agriculture. In fact, plant material inspires modern medicine so the more we know about essential oils, the more advanced medicine and agriculture become.

Even cooler, many essential oils work synergistically with one another, making them even more effective than when used alone.

I’ve collected a list of different essential oils for plants from here and will summarize the relevant research findings that can help you choose the best essential oils for your houseplant needs.

How to make essential oil plant spray

No matter what kind of essential oil plant spray you’d like to make for your indoor or outdoor plants though, the preparation and administration is roughly the same. You mostly just need a spray bottle, your chosen high-quality essential oil, and filtered/distilled water.

What you need:

• glass spray bottle
• filtered water
• chosen essential oils

Instructions: 

• Mix the recommended amount per essential oil with filtered or distilled water in a glass spray bottle (about 500 ml / 16 oz). 
• Spray on plant leaves from 6 inches away. 
• Stop treatment if the plant shows signs of stress.

I recommend a glass spray bottle in a darker color. This way, the plant essential oils do not mix with the plastic like when using a plastic spray bottle. Plastic releases hundreds of pollutants into the liquid it contains, some of which could interact with the plant essential oils (and pollute your plant soil).

I also like the darker amber colored glass because it prevents too much sun and light from getting into the water. Algae more easily grows in water with ample light, so the amber color helps protect your mixture so that it will last longer.

When spraying your mixture, hold it about 6 inches away from your houseplant and mist lightly on one area of the houseplant to test.

If the infestation is terrible, then it’s possible that the plant is too weak to sustain strong treatment. Testing a small area and diluting your mixture further if you suspect that your plant may be sensitive to treatment. 

Recipe: essential oil spray for plants

These are the most powerful all natural insecticidal recipes that you can make today. Clove oil is a popular choice among gardeners, so a simple clove oil spray may be enough. If not, then I also include a robust insecticidal recipe that combines the most effective essential oils against garden pests.

Clove oil insecticide recipe

Clove oil is more powerful than neem oil, so a simple mixture of just clove essential and filtered water will work here.

• 8-10 drops of clove essential oil
• filtered water

Essential oil pesticide recipe

All the ingredients in this recipe are general repellents and cinnamon oil is the most proven to be effective of the repellents. Garlic oil will help terminate any existing pests that are hiding under plant leaves or at the roots, like spider mites, mealybugs, scale, or larvae of any kind. 

This is a powerful insect repellent, so use cautiously. Do not spray directly onto plant leaves. Spray from 6 inches away and let the mist lightly coat the plant leaves.

• 2 drops of cinnamon essential oil
• 2 drops of garlic essential oil
• 2 drops of clove essential oil
• 2 drops of oregano essential oil
• 2 drops of citronella essential oil
• filtered water

Essential oils for bugs on plants

Where there is direct research to support a treatment method for a specific kind of insect, I’ll list it here. Otherwise, my recommendations are based on the general insecticidal research per essential oil.

Essential oils for gnats

Citronella is effective against gnats and the rest of the ingredients are effective against flies. This spray is the ultimate fly repellent, or fumigant as they call it in the science world.

• 3 drops of citronella essential oil
• 2 drops of basil essential oil 
• 2 drops of lavender essential oil
• 2 drops of orange essential oil
• filtered water

Essential oils for aphids

This study combined four essential oils together and found that the combination was 20 percent more effective as treatment for aphids than each of the essential oils could do on their own. The synergistic effect of the essential oils makes this spray so powerful.

• 2 drops of black pepper essential oil
• 2 drops of eucalyptus essential oil
• 2 drops of rosemary essential oil
• 2 drops of tea tree oil essential oil
• filtered water

Essential oils for mealybugs

Citrus oil is effective against vineyard mealybugs and could be effective against the mealybugs on your potted plants. Try spraying this mixture on affected areas to begin with. Spray your plant every few days, skipping days if your plant responds negatively. If the mealybugs are especially bad, then they’re likely in the soil too. Spray around the base of the plant and sprinkle cinnamon powder on the soil and around the base of the plants. 

• 10 drops of citrus essential oil
• filtered water

Essential oils for thrips

This scientific review found that plant essential oils are effective in treating thrips, most notably extracts of chili pepper, neem, orange peel with African curry leaf (Gmelina arborea L) or orange peel with Gmelina arborea L. 

While these exact essential oils are difficult to find, I’ve listed below oils from the same families. Mix these essential oils together to treat your thrips.

• 1 drop of chili pepper essential oil
• 2 drops of neem oil
• 2 drops of orange essential oil
• 2 drops of curry leaf essential oil
• filtered water

Essential oils for brown scale

Scale is relatively easy to manage by introducing natural predators but you may want to try essential oils first. In that case, I recommend first removing all visible scale with a cotton swab dipped in rubbing alcohol. I also like to use a toothpick to remove the smaller scale, which are translucent and harder to see. Once everything is removed, then you can spray the plant leaves with this all natural repellent. The garlic oil will help terminate any remaining scale that you may have missed.

• 3 drops of cinnamon essential oil
• 3 drops of garlic essential oil
• filtered water

Essential oils for spider mites

Rosemary oil is the most effective type of essential oil against spider mites. Spray this mixture on plant leaves and around the base of the plant every few days. Stop treatment if you notice the plant becomes stressed.

• 10 drops of rosemary essential oil
• filtered water

Common questions

Are essential oils safe for plants?

Yes, in most cases. In fact, essential oils are studied for agricultural pest control, meaning that millions of dollars per year are spent on trying to understand how to make a bug spray that not only can repel bugs but also is safe for humans and plants. That being said, it is important to note that essential oils are extremely concentrated and the active constituents are more powerful per volume than you might find out in nature. So without proper dilution, you could accidentally harm your plants instead of helping them. Use these with caution and pay close attention to how your plants respond. Infested plants often have weakened immune systems and may not be able to handle strong treatment.

Will peppermint oil hurt plants?

Peppermint oil shows promise as an effective insecticide, so it definitely can work well with plants. The important thing is that you dilute the pure essential oil significantly, like around 10 drops per 16 ounces.

What essential oil kills fungus?

• citronella essential oil
• clove essential oil
• cinnamon essential oil