neem oil marijuana

Organic Pesticides for Cannabis: Neem Oil

Neem oil is one of the most used organic pest control products out there because it can not only prevent but also eliminate a wide variety of bugs and pests while not affecting beneficial insects that are friendly to your plants.

This organic pesticide is used in almost all crops, not only cannabis and even though it doesn’t affect the bugs directly, it prevents them from feeding and laying eggs, forcing them to look for other plants to feed from.

1. What is Neem oil made from?

Neem oil comes from the Azadirachta indica tree, commonly found in India, South Asia, and introduced to lots of other subtropical and tropical countries for its importance in organic farming and medicine.

Not only is it used in plants, but Neem oil is also good for the skin in the treatment of several diseases, used as anti-bacterial, anti-fungal, but remember you shouldn’t use it unless your doctor recommends it because there have been reports of Neem oil poisoning 1 in adults and children, so be careful.

When a Neem tree flowers they produce not only small white flowers but also a small green or yellowish fruit that resembles an olive, these fruits (and the seeds) are where Neem oil is extracted from.

By grinding and pressing the fruits and seeds, manufacturers can obtain the purest form of this oil, although it can also be extracted with solvents it will diminish the quality.

2. How to use Neem oil

Before using your preferred mix of Neem oil, you should always test it on one leaf and wait for 24 hrs to see how your plants react to it after you know it is safe to use it, you need a sprayer to completely coat your plant, including the branches and underside of the leaves so the bugs don’t have a spot to run away from it.

Here are a couple of recipes that aren’t too strong, you can always increase the amount of Neem oil you mix but these ones are quite light and won’t have a bad effect on your plant.

Neem oil alternatives

5ml of baking soda per 1L of water

500 ml of 70% alcohol with 500ml of water

Have in mind that Neem oil indeed can be used in the flowering stage but only on the stems and branches, but bugs will run away from it and hide where you haven’t applied Neem oil (the buds), so it is better you don’t use it.

Also, plants absorb neem oil and it stays in their vascular system and can alter the taste and flavor of your buds, so it’s better to use the alternatives given in the table above before applying Neem oil.

3. How and when to apply Neem oil

Neem oil can be used as a foliar spray and used as a drench to water the soil in any stage of cannabis’ plant growth (although it is not recommended on the flowering stage), it has shown to be more effective as a foliar spray but will depend on what you’re using it for.

If your plants are suffering from fungus gnats larvae or other bugs that live in the soil, you can use it as a drench, Neem oil will last up to 22 days in the soil but only 45 minutes when mixed with water to be used as a foliar spray.

So depending on what you’re using it for, you will have to repeat the process a couple of times.

Neem oil against bugs

A Neem oil insecticide is super effective against more than 200 kinds of bugs including Aphids , Mealybugs, and Whiteflies .

So, how does Neem oil work ?

Despite not killing bugs automatically, this organic pesticide can prevent insects from feeding, larvae from maturing, reduces mating, and can also coat the bugs, preventing them from breathing.

Depending on your case (if you’re preventing or controlling a pest) and the percentage of Neem oil present in the product you’re using you should dilute it in water, for example, a product that contains 70% Neem oil should be mixed at a ratio of 7ml per liter of water and used as a drench or sprayed throughout all the plant, including the underside of the leaves.

If you’re using it as prevention, you should use it once a week or even once every two weeks but if you’re trying to control and eliminate bugs already present it should be used once every 5-7 days.

Neem oil as a fungicide

There are several ways of dealing with fungi, and Neem oil is one of them.

A Neem oil fungicide can be used to treat Root rot and Powdery mildew but will depend on the stage your plant is in, if your plant is in the vegetative stage you’ll be fine but if it’s in the flowering stage you should avoid using it.

Is neem oil safe for flowering plants?

Even though Neem oil is safe for flowering plants, it will alter the taste and aroma of the flowers.

Neem oil has a really strong and unpleasant smell and taste, it is not recommended to use it either as a foliar spray or in the soil in the flowering stage because neem oil is absorbed by your plant and it will stay in the vascular system for a while.

If you need to treat fungus or bugs in the flowering stage you’ll be better off using alternatives such as mixing alcohol or baking soda with water.

Is neem oil safe for humans?

Since Neem oil is very potent, it is not 100% safe for humans and animals. Ingesting as little as 20ml can cause vomiting and convulsions. Even though it may seem a bit crazy to drink Neem oil, there have been lots of cases of Neem oil toxicity and it can also affect liver and fertility.

It is advised children and pregnant women stay away not only from Neem oil but from all Neem products in general.

In some parts of Europe (like the UK) the sale of Neem oil is controlled and regulated , so even though it’s organic and considered safe, you should always avoid touching your face when dealing with Neem products.

4. When not to use Neem oil

You should not use Neem oil on plants that have suffered from overwatering , overfeeding, or nutrient deficiency stress recently, even though you can if you need to control a pest fast, it’s better to wait until your plant completely recovers before applying it.

Also, you should not spray neem oil with the lights on (if you’re growing indoors), plants in direct sunlight outdoors or in extreme cold or hot should not be sprayed with neem oil because it can burn the leaves, branches, and stem, you should apply it at night or when the sun sets, and when the temperature is around 20 o C to avoid having problems.

5. In Conclusion

Neem oil is a great way to get rid of pests organically, but make sure you don’t use it in the flowering stage because it will affect the smell and flavor of the buds and leave them with an unpleasant harsh smell.

There are alternatives to Neem oil use in the flowering stage if you want to keep your harvest safe. If you’ve had a good (or bad) experience with Neem oil or have other homemade recipes please leave us a comment below!

External References

1. US National Library Of Medicine National Institutes Of health

Neem oil is a natural product used to prevent and eliminate pests, being widely used on all types of plants including cannabis because it's organic.

Neem Oil: The Organic Pesticide Of Choice For Cannabis

Neem oil can act as both a preventative tactic and cure for a number of insect and fungus problems. It doesn’t affect friendly insects and acts as a growth tonic that keeps marijuana vibrant. Neem oil is a must-have for the serious organic cannabis grower.



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.

Neem Oil


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 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.

Neem oil controls over 400 different insects and a number of pathogens that can affect cannabis. Don't put up with pests any longer by purchasing neem oil.