By Luke Sholl Reviewed by: Gloria Payá


Neem oil affects a wide variety of insects and plays an important part in an organic pest and pathogen management program. Sometimes, it appears as a deep green or mustard yellow, dark red, or pale green colour depending on the region and the extraction method used.

The neem tree grows prolifically on the Indian subcontinent. It is prized for the powerful effects of the concentrated triglycerides and triterpenoids contained within its oils. Neem oil is pressed from the seed and fruit of the neem tree and has been used horticulturally and in Ayurvedic medicine for centuries.

The list of benefits of neem oil for the human body are quite astounding. Those interested in natural medicine will really find some interesting uses. To this day, neem soaps and cosmetics are still produced and preferred in India.


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.

The application of neem every ten days acts as a prophylactic measure for pests and pathogens. Prevention is always the best policy. If there is not an active harm prevention policy in place, an infestation of some kind can occur. In this case, neem oil can also be used as a direct pesticide.

Examples Of Use:

  1. Removing the webs of spider mites, then spraying with neem will cure an infestation and return vigour to new growth.
  2. Fungus gnats are more difficult to control as they swarm, but leaf damage is far less with neem oil as the leaves become inedible. Used in conjunction with sticky strips, gnats can be brought under control quickly.
  3. When rinsed through the growing medium with water, neem destroys bad nematodes and makes the bodies bioavailable as nutrients.
  4. Aphids succumb quickly to neem oil, but it will not harm overfed lady bugs.
  5. With one application, leaf miner infestations disappear overnight.

how to use neem oil cannabis


How to mix 100% first press neem oil:

  1. 1 teaspoon of neem oil per litre of water. Neem oil is temperature sensitive and will solidify into neem butter or jelly at lower temperatures. This does not harm the oil; in fact, chilled neem will last much longer. A water bath of 30°C will return it to its liquid form for easy measuring.
  2. Warm water. It is always preferred to use warm water when mixing, then waiting for it to cool. The neem remains a liquid longer, and the surfactant emulsifies more efficiently. Use warm, not boiling water as some beneficial compounds can degrade.
  3. 4-5 drops of surfactant. Neem oil is hydrophobic on its own, and a surfactant needs to be used when mixing it with water. Standard liquid dishwashing soap, preferably non-phosphate, does a perfect job. Literally only use four or five drops per litre.

Once mixed, use an atomiser or one-hand pressure sprayer on the finest mist setting possible. Mist the top and bottom of the leaf surfaces. Turn plants 360° where possible to ensure complete coverage. When applied once every ten days, plants will have an invisible armour against pests and fungi.

Avoid using neem three weeks before harvest. The lingering oil can affect final flavours. Although, it would be very bad luck to have something go wrong in the last three weeks.

Used regularly during all growth phases, neem plays an important role in maintaining plant health. First, as pest and pathogen prevention. Secondly, as a topical solution if there is an infestation. Neem is an essential addition to any organic cannabis garden.

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