The organic pesticide can be effective at keeping your plants healthy.
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Key Takeaways
Gardeners have used neem oil to control pests for hundreds of years.
It is effective against a wide variety of insect pests, mites, and certain fungal diseases.
Photo:Mukesh Kumar/Getty Images
While maintaining plant health is the first defense against pest problems, sometimes control measures are necessary.
How Does Neem Oil Work?
Neem tree seeds contain several compounds, but the main one responsible for pest control is azadirachtin.
This compound reduces insect feeding and disrupts the growth and development of immature insects.
Neem oil is most effective against the immature stages of insects.
However, it also impacts adult feeding.
Neem oil will not cure already infected plant tissues but helps limit the spread to healthy tissues.
In this capacity, it’s most commonly used against powdery mildew.
Check individual product labels for a complete list of approved plants.
Though neem oil is generally safe to use, some plants can be sensitive to horticultural oils and soaps.
So it’s always a good idea to test products on a small area before treating the entire plant.
Wait 24 hours after system to assess the treated area for signs of damage.
In fact, many neem oil products are listed as certified organic by OMRI.
However, these usually do not contain azadirachtin.
But they don’t disrupt insect growth and development.
Some formulations are mixed with other pesticides, such as pyrethrin, to provide greater control.
Azadirachtin
Products containing pure extracts of azadirachtin are also available.
These tend to be tailored toward commercial use and are often more expensive.
Begin by mixing the water and soap.
For a gallon of water use 1 teaspoon of soap.
For a quart spray bottle, reduce the amount of soap to 14 teaspoon.
Usually, a small amount of concentrated neem oil is added to a gallon of water for dilution.
Always follow specific mixing instructions listed on the product label to avoid under- or over-spraying your plants.
Cold pressed neem oil is highly concentrated and needs to be diluted for use.
Here’s how to dilute it correctly.
You will likely need a larger volume for soil drenching.
ensure to spray the bottom of the leaves thoroughly, as this is where many pests hide.
This is a good method for treating fungus gnat larvae, nematodes, and other soil-borne pests.
Though neem oil is generally safe to use, some people are sensitive to direct contact.
Wearglovesand a mask to protect sensitive skin and lungs.
So, don’t get discouraged if the issue doesn’t go away overnight.
Also, check the throw in of neem oil you’re using to confirm any additives are food-safe.
Concentrated neem oil generally has a shelf life of around 2 years.
Also, once you mix neem oil concentrate with water, it should be used immediately.
Neem oil can be used as a repellant to reduce the risk of pest infestation and some fungal diseases.
Most labels recommend applying neem oil at 10- to 14-day intervals to prevent pests.
When in doubt, follow the label.
Cold Pressed Neem Oil (025006) Fact Sheet.
Journal of Agricultural and Food Chemistry.
Horticultural Oils What a Gardener Needs to Know.
University of Nevada, Reno.
