Given the fluky weather in so many places, it's hard to tell if plants have gone dormant and even harder to know if they'll stay dormant. So it's no wonder I've been getting questions about when it's safe to apply dormant oil.
Dormant oil used to refer a certain type of horticultural oil. The first dormant oils were so heavy you couldn't safely use them on actively growing plants or you could damage the foliage. Dormant oils have since been refined, to produce lighter-weight oils that can be applied during the growing season without harm to most plants. Now a days, when the term dormant oil is used, it generally refers to the application timing, during the dormant season, rather than a type of oil. Here's the lowdown on what actually counts as a horticultural oil and when and why to use them safely.
Photo: © Marie Iannotti
Comments
Marie – You are absolutely correct in your descriptions of and use recommendations for a dormant oil spray. Dormant oils used in season do carry a risk of leaf damage, especially to tender crops. We recommend that if you want to apply in-season you carefully and fully follow the label directions and that you apply on a cool(er)day.
Best
Don Allison
Bonide Products
All mentioned products plus Neem oil are quite effective against spider mites, insects, and scale early in the year. Problem – phototoxic – don’t use it on bright days especially in warm weather.
I have added a link to a year-round natural horticultural oil enhanced with cedar oil for increased effectiveness.