What is Dormant Oil

Defined and Refined

So just what is dormant oil? While usually referred to in the more general terms of “horticultural oil,” dormant oil is a type of oil-based insecticide that is applied to trees, shrubs, and other plants during their dormant periods, before buds begin to open and there was no foliage. Though there was once a definite difference in formulations, horticultural oils have now become more refined and lighter-weight, which means that their application period is no longer limited to months of dormancy. Instead, “dormant oil” is now generally more a matter of timing, rather than type of horticultural oil.

Oiling It Up

Confused? You’re not alone, which is one reason many property owners leave the question to the professionals and hire a landscaping maintenance team who have their finger on the trigger when it comes to specialized lawn spraying services. To put it in layman’s terms for anyone even considering going the DIY route, however, the best place to start in answering the question of “What is dormant oil?” would lie in first defining horticultural oil itself. Across the board, whether referred to as “all-season,” “summer,” or “dormant,” horticultural oil is an insecticide made of oil, combined with an emulsifier that is then mixed with water and sprayed onto plants. Most oils used are mineral-based, though some formulations rely on vegetable oils that are naturally effective as insecticides. Think cotton seed oil, soybean oil, and canola oil. Regardless, they’re safer than chemical pesticides and insecticides, which also makes them ideal for edible gardening.

Early formulations of horticultural oils had heavier ratios of oil to emulsification agents, which also made them physically heavier and harder for plants with active growth to handle, because they could be damaging to delicate foliage. This is where the designation of “dormant oil” came in, because that heaviness made it necessary to adhere to an application that was limited to dormancy, when the foliage factor was taken out of the equation. Refining processes being what they are, horticultural oils are now lighter weight and cause no damage to foliage, so they can also be applied during active periods of growth; and now, if you run into a situation that actually specifies “dormant oil,” you’re simply being advised on when to apply the oil, rather than on which specific type of oil.

Give bugs the slip and make them toil with oil! Call the team at Executive Landscaping, Inc., a call today!