If you tend to buy healthy/organic/non-toxic versions of many household products, you may have seen ‘neem oil’ listed in the ingredients.
It’s used in formulations such as toothpaste and shampoo, or you may use a neem oil soap.
As a natural insecticide, fungicide and bactericide, people have been using neem for thousands of years.
And many of the benefits we get from using it ourselves translate to the garden, too.
To get those benefits, you want to find a pure neem oil that’s a cold pressed neem oil, organically produced.
So what is neem oil? It comes from the seeds of the neem tree, Azadirachta indica, now grown in over 70 countries all around the world.
For many years I avoided using neem oil for plants because I tend to stay away from anything that might be considered a pesticide, but I’ve been reading more about it over the past couple of years and my opinion has changed.
I started experimenting with it on my fruit trees last year, and now believe it’s one of those rare phenomenons that repels pests without causing too much trouble for the beneficial organisms in our organic gardens.
I successfully controlled aphids and mildew, and the really cool part is that the leaves I sprayed were noticeably healthier than the ones I didn’t, which proved to me that this is not like most pesticides that harm plants.
There’s even anecdotal evidence, mostly coming from organic orchardists who swear by a whole list of neem oil uses, that it’s actually helpful for the soil and arboreal food web.
That’s why I called it the ‘healthy’ pesticide.
I still wouldn’t spray it haphazardly around the garden, but if you experienced some pest damage last year, I believe cold pressed, pure neem oil is potentially one of the best options to improve your situation this year. Read on below to see why…
First, Does Pure Neem Oil Cause Any Problems?
The neem tree, Azadirachta indica, is native to the Indian subcontinent including Sri Lanka, Bangladesh, Pakistan and Nepal.
The great thing about neem seed oil is that it mainly affects plant-feeding insects that suck or chew on leaves, so beneficial insects including bees, butterflies and other pollinators that feed on nectar aren’t much affected.
Other beneficials such as ladybugs, earthworms and spiders aren’t affected either unless they’re sprayed directly with a fairly heavy dose.
Research shows that only repeated applications of very high concentrations of neem – far exceeding those you’ll be using – had a small impact on some bee populations.
Personally, I still wouldn’t advocate blanketing the whole garden with neem oil like I do with microbial inoculants and liquid fertilizers, but some advocates including well-known orchardist and author Michael Phillips do use it as part of a regular spray program, mixed with liquid fish and other biostimulants.
As for human safety, pure neem oil is not only natural, but is actually used in many applications for our health – neem oil for skin, neem oil for hair, neem oil for dogs, and so on.
The residue from spraying your vegetables is non-toxic, but you don’t want to ingest it. Neem oil can be irritating to eyes, skin and stomach, and negatively impact fertility, so as with most things we spray in our garden, don’t drink it or go splashing it all over your face.
WebMD says, among other things, “Taking neem seeds or oil by mouth is LIKELY UNSAFE for children. Serious side effects in infants and small children can happen within hours after taking neem oil. These serious side effects include vomiting, diarrhea, drowsiness, blood disorders, seizures, loss of consciousness, coma, brain disorders, and death.” and “Neem oil and neem bark are LIKELY UNSAFE when taken by mouth during pregnancy. They can cause a miscarriage. Not enough is known about the safety of need during breast-feeding. Stay on the safe side and avoid use.”
Neem breaks down quickly without a lasting residue and has a low environmental impact. You can spray neem pretty much up to the day of harvest as it breaks down quickly.
The only thing to be careful of is not to spray too close to waterways because neem oil has been shown to be mildly toxic to aquatic organisms.
Neem Oil Pesticide – How It Works
Neem oil insecticide uses. Pure neem oil can kill soft-bodied insects and mites on contact, which is one reason why you want to spray it in the early morning or evening when the pollinators aren’t out as much, to avoid spraying them.
But that’s not the main method of action of how it controls pests.
First, neem oil repels insects and other animals directly when they encounter it on the leaves.
And when you spray it on the soil, the plant will take it up systemically, which will deter insects from feeding even more.
But for those insects who do still feed, the oil contains many different components that are not going to bode well for them, the most active and well-researched being a metabolite called azadirachtin.
When a plant-feeding insect feeds on a leaf that has been sprayed with pure neem oil, the azadirachtin interferes with the insect’s hormonal system, which inhibits their eating, mating and egg laying patterns. It also inhibits growth which prevents larvae from moulting and eggs from hatching.
Because azadirachtin acts on the hormonal system, insects don’t develop resistance in future generations, thereby making it a sustainable solution.
While azadirachtin is the most researched metabolite, I expect there are many others that are involved.
Neem oil fungicide uses. Organic compounds in the oil spark an immune response to prevent fungal diseases such as mildew, black spot, rust, rot, scab, leaf spot and blights.
And a quality, cold pressed neem oil will occasionally control some of these diseases when they’re already present.
It’s also been used as a seed treatment to successfully prevent phytopathogenic fungal diseases, but I’ve not used it for that myself.
A Brief Word On “Pests”
I’m using the word pest a lot in this article and I’d like to speak to that.
We call something a pest because it’s doing something we don’t like, but really, it’s just an animal or microorganism doing its job.
I may think about the tomato hornworm as a pest when it chows down on my tomato plants, but in reality, the reason it’s doing that is because my tomato plants aren’t optimally healthy.
As I’ve talked about before, insects and diseases don’t cause much problem when our plants are healthy, so when we see that they are causing problems, our first plan of action should be to improve plant health, not to reach for the pesticide, because that won’t solve the root cause of the problem.
Both of these help boost plant health, sometimes enough to make the “pests” go away entirely, sometime just enough so they don’t cause as much of a problem, and sometimes it doesn’t seem to help much at all, because it may be that something else is going on.
So the other thing I do is think about what else could be contributing to the problem – improper watering, airflow, sun exposure, soil imbalances, etc. There’s always a reason, whether or not I can figure it out.
Traditionally, an organic pesticide is the last thing I reach for. Now, the cool thing about pure neem oil is that it actually seems to boost plant health too, whereas most pesticides harm plants, so I do reach for it sooner than I would with other pesticides.
But I still want to remember to also bring in some foliar nutrition and some beneficial microorganisms, to take more of a holistic approach to addressing the root cause of the problem.
So yes, I use the word “pests” because then we can all understand what I’m talking about, but really, they’re just insects and fungi that are trying to remove the unhealthy plants from my food supply.
I suppose we should be saying thanks to the pests, but we do love our tomatoes don’t we?
Okay, back to neem oil…
Other Pure Neem Oil Benefits
Neem oil is nutritious, so it actually acts as a foliar fertilizer.
But perhaps more important, the fatty acids are especially good for plants and some fungi.
A lot of research I’ve come across states that neem is good for soils, too, but they don’t usually say much more than that, so I can’t speak to it much. I think because most research is focused on using neem oil for plants as a pesticide that the soil benefits are considered secondary.
But I do know that a ‘neem cake’ is made from the organic residue after pure neem oil is pressed from the seeds, and that cake is used as a soil conditioner.
Do You Need Neem Oil For Plants?
If your plants are generally healthy and you don’t have much in the way of insect or disease problems, I wouldn’t suggest neem oil.
Some proponents recommend it be used regularly, almost like a broad spectrum fertilizer, and maybe there’s something to that, but personally, I don’t want to kill insects unnecessarily, so I save this for plants that really need some extra help.
In that case, it’s my number one choice. It helps control nearly 200 species of insects, 15 of fungi and allegedly some bacteria and viruses.
It’s most effective for either eradicating or at least deterring insects feeding on leaves. Here is a list of some of the main insects it can help control:
black headed caterpillars
boring insects (many types)
Colorado potato beetles
corn ear worms
fruit sucking moths
Mexican bean beetles
mites (not an insect)
moths and moth larvae
red palm weevil
root weevil adults
Some people have also had success controlling snails and slugs, but not always.
Finding A Quality Neem Oil
In terms of where to buy neem oil, be sure to seek out a product that is a cold pressed, 100% pure neem oil, preferably organic.
Pure neem oil for sale that was cold pressed contains much higher levels of active ingredients, which makes it more effective.
If possible, try to find the percentage of azadirachtin. This particular product varies between 1800-2200ppm. A higher ppm is achievable, but often by way of chemical extraction.
Commercial neem sprays often have chemicals added to them and often only include a neem oil extract with just the azadirachtin which greatly limits the effectiveness.
The Garden Safe neem oil and Bonide neem oil brands both have 30% “Other” ingredients and they don’t disclose what those are.
What you want is a pure, cold pressed neem oil, not an extraction, and free of additional harmful ingredients.
How Much Neem Oil Do You Need?
I just keep a 16oz size around my house because that’s plenty for my home garden.
That size will do about 1000 square feet of orchard for a whole growing season, and several times that size for a vegetable garden.
How To Use Neem Oil For Plants
You can use neem oil throughout the growing season on all types of plants. Just be careful with seedlings and young plants in general, as they tend to be more vulnerable to any type of spray.
It’s best to start early in the season to prevent the main infection period of fungi, disrupt egg hatch of soft-bodied insects and target overwintering moths in the trunk and soil.
On plants that you know will have pest problems, you can spray for prevention every 1-2 weeks starting in late winter, and especially when the problem season approaches for that plant, and then for maintenance every 2-4 weeks after that.
If you have a specific pest to control, you can spray every 3 days for at least 2 weeks. This is approximately the length of one life cycle for many insects.
It’s best to apply early in the morning or even better is in the evening to make sure you’re avoiding the hot sun, as some sensitive plants may get burned.
Here’s what orchardist Michael Phillips says about when to use neem oil: “I apply pure neem oil along with liquid fish at the week of quarter-inch green, pink, petal fall, and 7 to 10 days after that. This early season program addresses many orchard health fronts including the primary infection period of fungal diseases like scab and rust. I continue to use neem through the summer on a 10 to 14 day schedule, again coinciding with any other specific spray needs. A late August spray on the later varieties finishes up the use of neem oil for the season here in northern New Hampshire.”
If you want to know what he means by “quarter-inch green” and so on, here’s an example for an apple tree.
Like unrefined coconut oil, pure neem oil becomes solid and thick at cooler temperatures, so if necessary, you can warm up the whole bottle by placing it in a pot of warm water, or you can just mix the neem directly with warm water before spraying. Don’t use hot water as heat destroys azadirachtin.
The oil and water will separate, so you’ll need to use an emulsifier to stabilize the mixture. Generally what’s used is liquid soap, which also has insecticidal properties. Unfortunately, dish detergents are quite hard on plants, so I use a non-toxic Castile soap such as Dr Bronner’s. More on this below.
Total application rate of neem oil is 1-2 cups per 1000 square feet per year, which could be divided into small-dose, weekly sprayings or larger-dose, monthly sprayings. For example, if you spray 6 times this year, that’s about 3-6 Tbsp of neem oil per 1000 square feet each time. Lean to the lower end if your plants are small, like vegetables in spring.
To mix, add the soap to the warm water first and then slowly stir in the neem oil. Per gallon of water, mix 1/2 teaspoon of non-toxic liquid soap and then add 1.5 Tbsp of neem oil and shake like crazy before and during application to keep it emulsified. Don’t use dish detergent – use a true liquid soap.
This makes for a 1:170 ratio of neem oil to water (1:150 to 1:200 seems to be the normal recommendation). That amount will do about 250-500 square feet, but don’t spray too much on young seedlings – it’s better to wait until plants are bigger for most types of foliar spraying, as tiny plants can be quite vulnerable to overapplication.
If you’re using a standalone sprayer and plan to spray, for example, 3 gallons of water, that’s about 1/2 Tbsp of soap and then 4.5 Tbsp of neem oil. For soil and trunk applications in early spring and late fall when there are no leaves on your trees and shrubs, you can double the dilution to 3 Tbsp of neem oil per gallon of water, but let’s stick with 1.5 for this example.
If you’re using my hose-end sprayer or a similar pint-sized sprayer, here’s how I do it. Fill it 3/4 full with warm water, add 1/2 Tbsp of non-toxic liquid soap, and shake shake shake. Then, slowly pour in 4 Tbsp of neem oil while vigorously mixing the liquid. This is similar to how a good salad dressing is made – the oil needs to be added slowly and mixed really well in order to emulsify it. Alternatively, using a blender to mix this all together can work, but then your blender smells like neem, which isn’t very nice.
Then set the hose-end sprayer to setting 10. The reason I mix it with so much water in the sprayer is that it’s almost impossible for the sprayer to pull up straight neem oil, so mixing it with this water makes it less thick, allowing it to be pulled up. If it pulls up too fast, you can go down to setting 5.
Even better, use less water and instead add some liquid fish and/or liquid seaweed fertilizer and spray them at the same time. I always try to combine products when possible since I’m out there spraying anyway, and fish and seaweed are the best matches for pure neem oil.
I don’t mix this with microbial inoculants because I don’t think the microbes would like the oil, so I come through with my EM or compost tea a few days later or whenever I get to it.
Use your neem and water mixture within 8 hours because it will break down afterward. Then clean your sprayer immediately to keep it from clogging up with oil.
When you spray the leaves, make sure that you also spray the undersides because insects like to hide there.
It’s always useful to spray the soil too because insects lay their eggs in the ground, and because the fatty acids in the oil are beneficial for the soil food web.
Don’t be discouraged if you don’t see immediate effects. Remember that neem oil concentrate primarily works not by contact, but by disturbing the hormonal systems of insects, so it can take some time.
If you have any questions about neem oil, let me know down below.
I go into more detail about ordering on the main page, but here are a few quick things I’d like to mention:
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Neem Oil For Sale – Order Now!In summary, this neem oil:
- Helps control nearly 200 species of insects and 15 of fungi, without causing much harm to beneficials such as bees, butterflies and earthworms, but I still suggest it be used sensibly only on plants that need it.
- Also seems to act as a biostimulant, encouraging a healthier soil food web. It is especially advocated by organic orchardists such as Michael Phillips as part of a regular spray program.
- Is 100% pure and cold pressed, which makes it much more effective than the cheaper products that are just extracts of neem.
As a free bonus when you order today, I’ll also enrol you in my online course on controlling plant predators.
Just click ‘Add To Cart’ up above!