Boise’s winters may be cold, but that doesn’t mean pests take the season off. In fact, many insects overwinter (or in other words, live through winter) in tree bark, crevices, and on shrubs, patiently waiting for spring to return so they can infest your lawn. One of the best ways to protect your trees and shrubs from these pests is by applying dormant oil in early spring. This method is an effective, environmentally-friendly way to keep your landscape healthy and pest-free.
What is Dormant Oil?
First, let’s be sure we understand what dormant oil is. Dormant oil is a highly refined horticultural oil that’s mixed with water and sprayed onto trees and shrubs during their dormant period (late winter to early spring). The oil works by smothering insect eggs and overwintering pests such as aphids, mites, and scale insects before they become active in the spring, basically suffocating them before they have the opportunity to emerge. Because dormant oil is applied before new growth begins, it helps prevent infestations without harming beneficial pollinators that arrive later in the season. Good for your trees and the bees! Learn more about dormant oil by reading this article.
Which Plants Are Safe for Dormant Oil Use?
So which plants are okay to treat with dormant oil? Dormant oil is safe for use on a variety of trees and shrubs, including:
- Fruit trees: apple, pear, cherry, peach, etc.
- Shade trees: maple, oak, birch, etc.
- Ornamental shrubs: boxwood, lilac, roses, etc.
- Evergreens: certain pines and spruces, although some species may be sensitive—check with a professional before application to be sure you don’t damage your trees!
While these plants are generally okay with dormant oil, it’s always best to consult with an expert, like our team at All Seasons Lawn Care, to determine whether your specific plants are suitable for dormant oil application. Have questions? Click here to send us a message.
How is Dormant Oil Applied?
Although the process may seem simple from our description, applying dormant oil requires the right timing and technique. Here’s how it’s done:
1. Choose the Right Time – Apply dormant oil in late winter (typically March in Boise and the surrounding area) when temperatures are consistently above freezing but before buds begin to swell.
2. Proper Mixing – The oil needs to be diluted with water to the appropriate ratio for safe and effective application.
3. Thorough Coverage – The oil is sprayed onto trees and shrubs, ensuring all bark crevices, branches, and stems are coated to target overwintering insects.
4. Drying Period – The oil must dry before temperatures drop to prevent damage to plants. A good rule of thumb is when outside temperatures stay above 32 degrees for at least twenty-four hours.
Is Dormant Oil Safe?
Dormant oil is considered safe for the environment, pets, and humans when applied correctly. It’s low in toxicity and doesn’t linger in the environment like synthetic pesticides because it breaks down faster. However, proper application is key to avoiding plant stress or damage. This is why professional application by experienced lawn care specialists is recommended. It’s always better to play it safe!
Will Dormant Oil Harm Beneficial Insects?
Remember, dormant oil usually only targets one life cycle of pests. Since it primarily targets overwintering insect eggs and pests, it’s one of the most eco-friendly pest control options available. It doesn’t harm beneficial insects like bees, ladybugs, and butterflies because it’s applied before they emerge in the spring. By the time these pollinators are active, the oil has dissipated, leaving no harmful residues.
Quick Tips for Dormant Oil
- Follow label instructions for every application
- Monitor your plants to determine which life stage the overwintering insects are in
- Give yourself plenty of time for application – a proper application requires thoroughness
- Don’t use on sensitive plants
- Test one section of the plant to determine eligibility
- Don’t mix with sulfur-based fungicides
Professional Dormant Oil Application in Boise, ID
Applying dormant oil at the right time and in the right way is crucial for protecting your trees and shrubs. Let the professionals at All Seasons Lawn Care handle it for you! Our team has years of experience providing expert lawn and tree care throughout Boise and the surrounding Treasure Valley area, ensuring your landscape stays healthy and pest-free well into the spring and summer.
Call today or send us a message to schedule your dormant oil application in March and enjoy a beautiful, insect-free landscape this spring!
