What is horticultural oil and how is it used?
Horticultural oil is extremely refined oil, suitable for use on outdoor plants to smother scale insects and insect eggs that are on branches and stems. It is sometimes called dormant oil. An even lighter weight oil, called superior oil or summer oil, is sold for summertime use. It’s an important distinction because a heavy application of oil when temperatures are high could cause burning of plant tissues. These refined oils can be from petroleum or from plant oils, depending upon the manufacturer.
