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How to Use Horticultural Oil in the Garden

As the days get warmer and your garden begins to flourish, it’s the perfect time to have a plan of attack against pests that may harm your burgeoning blossoms and vivacious veggies. Learning how and when to use horticultural oil to combat garden issues is a valuable skill to have. Read on for our guide on how to use horticultural oil in your garden.

What is Horticultural Oil?

Horticultural oil is known by many other names. You may have heard terms like dormant oil spray; all seasons spray oil, volck oil, or summer oil. Each type is different, but they all fall under the umbrella of pesticides that help protect plants from insects and disease. Pesticides that are oil-based are effective and more eco-friendly than older versions of pesticides. These oils were developed for home gardeners that need some help controlling pest issues. Many of these oils are created to be able to be mixed with water to form a spray for easier use.

Horticultural oils are what you call in when you’ve used other tricks to deal with plant pests and disease. Think of horticultural oil as your tough cousin that you only call when you need the big guns. Knowing how and when to use horticultural oil is key: try other forms of pest control like natural neem oil or insecticidal soaps before you turn to horticultural oil.

How do Horticultural Oils Work?

Horticultural oil is composed of mineral oils, which is petroleum that has been refined. It’s a harsh chemical that will kill off many types of insects, good or bad. Because it’s deadly to insects, you should use it sparingly to protect good bugs and to prevent needless chemical damage to your garden. You should always check the label before using any product on your plants, and be sure to follow directions.

Types of Horticultural Oil

How we use horticultural oil has evolved over the years, and the product itself has had to change, too. Some types of horticultural oil were too powerful and would easily kill any plant matter it touched. Depending on your pest control needs and the time of year, you can select a horticultural oil that will help. Below are some terms to become familiar with when buying horticultural oil. If you’re feeling overwhelmed, remember you can also contact us for help.

Dormant Oil is applied during a plant’s dormant stage in winter. It’s applied before the plant starts to grow in spring.

Delayed Dormant Oil can be applied after a plant’s deep dormancy but before it starts to grow too much. You can apply it when buds are just beginning to show, between 1/16- ½ inches.

Summer Oil, Superior Oil, or Supreme Oil can be applied to leaves that are fully grown. These products don’t contain harsh sulfur that can burn leaves. There are subtle differences between the three of these products, but they will essentially serve the same purpose.

Nonselective: If you see this term on an oil product, be aware that it will kill both pests and beneficial insects alike. Use with caution.

Knowing what horticulture oil you are using will also help guide how you use it. It may be wise to pick up a few kinds or opt for an all-purpose oil that you can use throughout the year.

What Pests Can Horticultural Oil Help With?

Horticultural oil is incredibly useful against an array of different pests and diseases. Some of the most common pests that drive people to use horticultural oil are mealybugs, mites, thrips, scale, whiteflies, leafhoppers, and aphids. Horticultural oil can also help with issues like powdery mildew and various plant viruses.

How to use Horticultural Oil in the Garden

The first step before learning how to use horticultural oil is to determine if you need horticultural oil. Research the issue you are having with your garden and try other pest control products or treatments. Once you have determined that it’s time to call in the horticultural oil, make sure you are using the right kind for your type of plants. Keep in mind that many types of trees like maples, junipers, spruce, evergreens, and smoke trees are not compatible with horticultural oils. You should also keep oils away from any water sources as it is deadly to fish. If you notice the leaves are yellowing after your first application of horticultural oil, stop the application process and reassess: you should probably try an alternative treatment.

Horticultural Oil Safety

Remember that horticultural oil is a pesticide, be sure to protect your plants, your property, and yourself when using it. Always check out other ways to treat pests before resorting to harsh chemicals. When you use horticultural oil, you’ll notice how quickly the excess oil dissipates. This is a safety feature that prevents leftover toxins from lingering and causing a hazard to people and pets. Finally, consider the health and safety of your plants and garden. Improper horticultural oil use can lead to phytotoxicity, which is essentially a plant chemical burn.

Other Tips for Using Horticultural Oil

Do wait for a mild day to apply horticultural oil. Avoid very hot days (100 degrees or higher) or freezing temperatures.

Don’t use horticultural oil on plants that are stressed or struggling with drought.

Do learn how to use horticultural oil during the appropriate season. Generally speaking, avoid fall application, which makes plants susceptible to horticultural damage.

Don’t use horticultural oil on plants that are wet or in high-humidity environments. Too much moisture will slow down the excess oil’s evaporation process, leaving behind enough of the chemical to burn the plant.

Don’t be intimidated! Learning how to use horticultural oil is a great skill to have and will help you in all your future gardening endeavors.

If you’re looking to find out more about how to use horticultural oil In Allentown, come visit us! We’re always here to help you troubleshoot any gardening issues you’re struggling with.


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