Neem oil is a natural and safe insecticide that is effective against many common cannabis pests. Learn how to use it directly in the grow room! Neem oil is made from the seeds of the Azadirachta indica tree, which is native to South Asia. The active insecticidal component in neem is azadirachtin. What makes Neem so special is that it is 100% natural and safe. It is not toxic to humans and animals. When used correctly, neem oil has no negative effects on the plants. Neem oil is very effective against many of the most common cannabis pests. It is particularly suitable against soft-skinned insects such as spider mites, aphids and greenhouse whiteflies. It is also fungicidal and is effective against fungi, mold and mildew. In order to maximize its positive effects, it is important to understand how neem oil works.