There are several different recipes available for homemade dormant oil. These concoctions are effective at smothering many common garden pests, such as spider mites and aphids, as well as killing fungi that lie in wait for warmer weather to attack fruit trees and other valuable plants. Dormant oils are applied roughly between November and March, or when the plants in question are dormant.
Combine 4.5 litres (1 gallon) of water, 2 tbsp of ultra-fine canola or horticultural oil and 1 tbsp of baking soda. This mixture was developed by researchers at Cornell University. Shake the mixture well to combine all ingredients.
Pour the mixture into a sprayer or hand-held spray bottles for small-scale jobs, individual plants or precise applications.
Spray the oil on your plants on a sunny, windless day. Try to achieve the most complete coverage you can.