I spray just a bit into the soil as I’m filling the container. Ensures that any eggs that came in with the soil are neutralized.
RQS says this:
The organic cannabis grower will find the benefits of neem oil to be a pest and fungus-free garden. Neem oil remarkably only targets bad bugs in your garden and leaves good bugs alone. A regular application will suppress spider mites and white flies, fungus gnats, and nasty nematode infestations. Ladybugs and butterflies, bees, and earthworms all remain unaffected.
Regular application also suppresses a number of other pathogens that can affect cannabis. Powdery mildew and rust, rose black spot, and other fungi endemic to humid and still conditions cannot take hold. Neem oil can also be watered into the growing medium to prevent or control root rot, while acting as a mild growth stimulant.