As an organic gardener, I prefer using natural pesticides whenever possible, especially when it comes to my vegetable plants. I’ve read a great deal about neem oil and how it is excellent to combat insect infestations and fungal diseases. But, also, I have read mixed reports about its safety. So, I decided to delve into it and find the truth.
Is it safe to use neem oil on plants? Yes, neem oil is safe. Neem oil has been used as an insecticide on plants in India for over 400 years. Applying neem oil does not harm the plants, vegetables, or people eating them. Precautions do need to be taken when spraying neem oil, as some people may have an allergic or respiratory reaction.
Neem oil, it turns out, is an excellent resource in the great fight against garden pests. It doesn’t solve every problem, but it is a valuable tool to incorporate into the arsenal. The insecticide in neem oil is natural and is only found in neem. It is non-toxic as an applied insecticide. The type of neem used matters, as is the application process. Here’s what is important to know before starting to use neem oil for garden pest infestations.
If neem oil is sprayed on the plants, such as lettuce and kale, can I harvest and eat those greens right away, or do I have to wait a certain length of time?
As long as the greens are washed thoroughly, it is okay. However, spraying the oil on kale before harvesting doesn’t make sense. Harvest the kale first, then spray. Neem oil breaks down in 2-5 days on plant leaves. The ideal situation is to spray long before intending to harvest.
Is neem oil safe for humans, dogs, and cats?
The FDA rates neem oil as generally safe for humans. Neem oil extracts and components are used in toothpaste, shampoos, and soaps. The products aren’t fully concentrated neem, though, and not quite the same as what is used in insecticides.
Neem is potentially toxic if not used properly. The correct application of neem oil to plants and vegetables will not result in toxic amounts. However, it is best to wash all vegetables treated before eating. A thorough washing with water will remove the oil.
Neem oil may cause skin irritation or an allergic reaction. Caution is always advised when working with neem, for example, wearing protective clothing.
The ASPCA does not list neem as toxic to dogs or cats. Neem oil is moderately toxic to aquatic animals.
Which pests does neem oil kill?
Neem oil only works with soft-bodied insects, larvae and eggs. It does not kill hard-bodied insects, like beetles, though it can kill their larvae. It also works as a fungicide against white powdery mildew.
Some of the pests neem oil works against include aphids, mealybugs, caterpillars, spider mites, lace bugs, thrips, whiteflies, cabbage looper, leafhoppers, leafminers, and beetle larvae.
Not only that, but we rejoice in our sufferings, knowing that suffering produces endurance, and endurance produces character, and character produces hope, and hope does not put us to shame, because God’s love has been poured into our hearts through the Holy Spirit who has been given to us.
Romans 5:3-5
How does neem oil work?
Neem oil works as two functions. The sprayed oil coats the plant’s leaves. When the insect eats the leaf, the oil gets into the respiratory system and suffocates the insect.
The natural insecticide, Azadirachtin, disrupts insect systems. They don’t feed, fly, or mate; it inhibits all their hormonal behaviors, and eventually, they will die off.
Neem oil doesn’t work immediately. It takes approximately 72 hours for the insects to die completely. Results sometimes can be seen within 24 hours, but the full effect takes longer.
Does neem oil harm beneficial insects?
Beneficial insects like bees, butterflies, and ladybugs are not affected by the insecticide because they are not eating the sprayed leaves. They may land on the leaves, but that is not harmful. Eggs and larvae of butterflies or ladybugs could be affected if they are on the leaves. Be judicious and use it only on the plants infested with pesty insects; don’t do a widespread application.
When sprayed, neem oil kills all insects because the oil clogs up their airways and suffocates them. To avoid harming beneficial insects, do neem oil applications in the morning before butterflies and bees are out. Also, only spray the affected plants to minimize any harmful impact.
Which neem oil product is best?
At the garden store, there are many ready-spray neem-based insecticide products. Most of these contain hydrophobic extract of neem oil. This extract is parts of the neem oil combined with alcohol or a chemical. It doesn’t include the natural insecticide, azadirachtin. Don’t bother with these products. They don’t do anything more than vegetable oil does.
The best neem insecticide product is cold-pressed 100% neem oil. This contains all the properties of the neem seed, including azadirachtin. It needs to be mixed before use, but that is a simple process.
Here is a link to the 100% Cold Pressed Neem Oil that I used in the above pictures from Amazon.
How to Mix Neem Oil
Items needed
- A spray bottle or pump sprayer for mixing and application.
- 100% cold-pressed neem oil
- natural liquid dish soap (no chemicals, dyes, or fillers)
- water
Formula:
To 1-gallon water, add 1 tablespoon neem oil and 1 teaspoon dish soap.
*Up to 2 tablespoons neem oil may be used, but it is always best to start with the smallest amount.
Method:
- Add all the ingredients to the container and shake well to ensure the mixture is emulsified (combined). This is the purpose of the dish soap.
- If the oil is separating away from the water, add a bit more dish soap and shake again. The mixture should stay emulsified for at least 30 seconds. Add more dish soap if needed, but don’t overdo it as it will affect the way the oil adheres to the leaves.
- Use within 7 days.
How to Apply Neem Oil
- Wear protective clothing, like a long-sleeved shirt, long pants and a face covering.
- Do a test spray of one leaf to ensure the mixture won’t harm the plant. A mix with too much soap or too much oil may damage the leaves of some plants.
- Spray the entire plant, top to bottom, including underneath leaves where eggs and larvae are most likely to appear.
- Spray the soil around the plants.
- Apply every 7-14 days, as needed.
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Resources
Oregon State University, National Pesticide Information Center
Oregon State University, Profiles of Organic Pesticides
Clemson Cooperative Extension, Less Toxic Insecticides
Campos EV, de Oliveira JL, Pascoli M, de Lima R, Fraceto LF. Neem Oil and Crop Protection: From Now to the Future. Front Plant Sci. 2016;7:1494. Published 2016 Oct 13. doi:10.3389/fpls.2016.01494
