How to Make and Use Your Own Dormant Oil Spray at Home

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Dormant oil spray protects plants against insect damage by killing the eggs and insects that remain on the plant during the winter season. These pesticides are non-toxic, but their effects are short-lived and need repeated treatments.

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Dormant oil spray is used as a preventative measure to protect plants (especially fruit trees) against insects like scale, aphids, and mites. These insects may hide in the plant’s branches over the winter, and some also lay their eggs in the branches, which then hatch in spring and feed on the tree’s new growth.

Dormant oil sprays are an environmentally conscious and effective way to minimize the damage insects can cause to fruit trees. There are several ways to make a homemade version of dormant oil spray from ingredients that are already found in most homes. Homemade sprays are just as powerful as commercially available options, provided they are made and applied correctly.

What is Dormant Oil Spray Made From?

Dormant oil spray’s main component is either a plant- or petroleum-based oil, along with some type of emulsifying agent to allow it to combine with water for even spraying. In addition, some types of dormant oil spray contain fungicides or other treatments depending on the specific type of plant and issue they target.

Dormant oil spray works by coating the predatory insect’s exoskeleton or egg membrane, preventing it from getting oxygen. This kills the target insect but requires direct contact with the oil to be effective. The effect is short-lived, as dormant oil spray loses efficacy once it dries. This pesticide has no residual effects.

While no solution can completely eliminate the insects that feed on fruit trees, dormant oil can reduce the population significantly over the following growing season if used properly.

When Should Dormant Oil Spray be Used?

Dormant oil should be used when the plant is dormant, but not in extremely cold temperatures. It functions best at temperatures between 40 and 70 degrees F, so a warm late-winter or early-spring day should be appropriate for application. Use dormant oil sprays at least a few days before the first blossoms open.

How to Make and Use Your Own Dormant Oil Spray at Home

Moisture makes the spray less effective, so choose a time when the trees are dry and humidity is low. Check the weather forecast for the next 24 hours and do not treat plants if rain or cold temperatures are predicted. It is also best to avoid spraying on sunny days, as foliage can be burned by being exposed to direct sun before the oil has dried.

How to Make and Use Your Own Dormant Oil Spray at Home
How to Make Your Own Dormant Oil Spray

While there are many commercial dormant oil sprays available, many gardeners choose to mix their own. It can be more cost-effective and gives you more control of which ingredients you prefer to use in your garden.

There are several recipes for making your own dormant oil spray. Each one contains an oil base and an emulsifier, plus water. They should all work equally well, so you can choose which one suits your needs based on what ingredients you have on hand or what you prefer to use on your plants.

How to Make and Use Your Own Dormant Oil Spray at Home

Regardless of the recipe you choose to make your dormant oil spray, it is imperative that you stir or, preferably, shake the mixture thoroughly. This allows the oil and water to emulsify and prevents uneven application of the oil on your plant. Uneven application of a dormant oil spray might leave some insects alive if the oil doesn’t touch them, and it can also cause your sprayer head to clog.

How to Make and Use Your Own Dormant Oil Spray at Home

All of the recipes are provided based on a quart of water; for larger batches of dormant oil spray, multiply the amounts accordingly while maintaining the same ratios.

Recipe 1:

1 tablespoon canola oil
3-4 drops laundry detergent
1 quart water

Recipe 2:

0.25 cup vegetable oil
1.5 teaspoon liquid soap
1 quart water

Recipe 3:

0.5 tablespoon canola oil
1 teaspoon baking soda
1 quart water

How to Make and Use Your Own Dormant Oil Spray at Home
How to Use Dormant Oil Spray

Once you have mixed your dormant oil spray thoroughly, add it into a sprayer of the appropriate size for the area to be treated. For most typical gardeners, a pump sprayer works well, but a battery or gas-powered sprayer may be required for larger jobs. A hand sprayer may be sufficient if the treatment area is small.

How to Make and Use Your Own Dormant Oil Spray at Home

With your prepared sprayer, coat the plant with an even but thorough layer of the dormant oil. Be sure to spray the undersides of leaves as well as crevices on the stems and branches, as eggs are likely to be in these locations.

How to Make and Use Your Own Dormant Oil Spray at Home

The oil and water in your homemade dormant oil spray will naturally begin to separate, so shake the sprayer regularly as you treat your plants. Clean the sprayer immediately after finishing the treatment to keep it clear of oil blockages. A bit of dish soap can make the cleanup process faster and easier.

Is Dormant Oil Spray Safe?

In general, dormant oil spray is safe to use. It is non-toxic to humans and animals, and does not harm beneficial insects because they are generally not active in the winter. Be sure not to use dormant oil spray on trees that are already stressed, as the oil can cause additional damage. Only use this treatment on healthy plants.

Note that some plants can be damaged by oil treatments, so be sure to research the specific plant to be sure it is safe to use dormant oil spray. Also be sure to protect nearby plants from overspray.

How to Make and Use Your Own Dormant Oil Spray at Home

Oil sprays are generally not harmful to humans, but they can irritate eyes and skin upon contact. It is a good idea to use proper protection when handling and applying dormant oil sprays. The ingredients in dormant oil sprays can also create dangerous compounds when used in conjunction with sulfur-based sprays, so wait at least one month between treatments.

How to Make and Use Your Own Dormant Oil Spray at Home

Keeping in mind the warnings above, you should be ready to make and apply your homemade dormant oil spray. Remember that you will likely need to do multiple treatments for maximum effectiveness, but it should prove worthwhile once you see the dramatic reduction in insect populations on your fruit trees the following spring.