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When to Apply Dormant Oil?

Many gardeners know dormant oil is extremely useful in controlling scale and mites effectively BUT timing is essential.

Wait until the daily temperature is at least 40 degrees F. (4 C.), and will stay that way for at least 24 hours and when in  a 24-hour period,  no rain or high winds are predicted.

You can use a commercial product or a 2-3% solution of Canola Oil with a squirt of Dawn Dishwasher soap.  (2-3 tablespoons per gallon). Bottle end sprayers are helpful if you  have a lot of bushes to do.

Drench the branches and trunks. Start at top and move around the bush to soak it down.
Yews, magnolia, apples, crabapples, plums, quince and pears all benefit from dormant oil treatment, as do gooseberry and currant bushes. Know blue junipers will lose their blueness afterwards.  Do not spray japanese maples.
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Organic Insect Control

Late March/Early April is a good time to apply dormant oil spray to fruit trees,  cane fruits (raspberries, blackberries),  and ornamental shrubs and trees such as arborvitae, magnolia, yews, hemlock, spruce and junipers. Insects such as scale, mites and aphids are easily controlled this way.

The key is to wait for outside temperature to be above 40 degrees F. for a 24 hour period. 

Use a commercially available Dormant or Volck Oil spray but you can also use household canola oil, too. I recommend a 2% spray solution. For homeowners,  use a dial and spray bottle sprayer, with the gauge moved to 2 tablespoons per gallon. A tank sprayer can be used also.

Secondly, drench the leaves until spray ‘runs off’ leaves and branches.