Neem Oil is extracted from Neem trees and contains a compound called Azadirachtin that is useful for fighting common plant pests such as fungus gnat larvae, spider mites, and grasshoppers (see larger list below). Once Azadirachtin has been ingested by pests, it acts as an appetite suppressor and growth inhibitor causing failure to molt and starvation.
Used as a soil drench, Neem Oil acts as an systemic pesticide, meaning the plant will absorb the Azadirachtin compound and distribute it throughout its vascular system. Once distributed, any part of a treated plant a pest ingests will also contain the Azadirachtin.
Used as a foliar spray, the same principals of ingestion by insects still apply but primarily the Neem will act as a physical inhibitor to the insects by coating their bodies in the oil. By coating their bodies, the insect’s spiracles or “nostrils” become blocked and the insect suffocates.
Plant Pests Controlled with Neem:
Why Make Your Own?
The main reason we started making homemade Neem Oil spray is that most store-bought Neem sprays contain low levels of Azadirachtin, the primary ingredient responsible for pest control. Azadirachtin naturally degrades over time and can degrade within days if left at room temperature. Since most store-bought sprays sit at room temperature for several days or months before purchase, this can reduce the effectiveness by the time the product is used. Excessive heat exposure can also reduce effectiveness by breaking down the compound which is why it is important to buy Cold Pressed Neem Oil.
How to Make and Use Neem Spray
This is the recipe we use to help fight against fungus gnats and white and red spider mites in our nursery. This recipe is safe to use on plants but always test a small area before treating an entire plant or tray of seedlings. Do not include the soap if working with carnivorous plants.