How Use Neem Oil on Plants as an Organic Insecticide

Neem oil is the answer to many needs of gardeners. Do you need a fungicide, an insecticide, an antibacterial for your plants, Houseplants, flowers or crops but you don’t want to use chemical products?

Don’t worry, Mother Nature already has the solution: neem oil of course. Its popularity with gardeners and amateurs alike is growing very fast, and for good reason.

Neem oil is natural oil extracted from Azadirachta indica, or Indian lilac, and it works perfectly well as an insecticide, a fungicide and an antibacterial remedy for plants. It is fully natural and perfectly safe for your plants. Compared to synthetic products, it has many advantages, and it is safe to Humans too as long as you don’t ingest it.

So, if you want to know how it is made, when and how to use neem oil on plants , and, maybe above all, how to use it safely, you have come to the right place because this is exactly what we are going to see.

What Is Neem Oil?

What Is Neem Oil

Neem oil is the oil obtained by pressing the seeds of Azandirachta indica, also called neem, Indian lilac or neemtree. It is an evergreen plant that grows very fast and tall, which makes it very profitable to grow.

As one of its names suggest, it comes from the Indian Subcontinent, though it can be found in some areas of the Middle East as well.

Its fruits look a bit like olives, and the trees can be very big indeed; they can grow to be 130 feet tall, which is 40 meters, though most are about half as tall.

Making neem oil is, in fact, not dissimilar to making olive oil; when the stone is pressed, it releases an oil that can be of different colors, from golden yellow, to dark brown, brownish green ore even of a bright red shade. Its smell is very distinctive, and it will remind you a bit of peanuts and garlic combined.

What Is Neem Oil Useful for?

What Is Neem Oil Useful for

Neem oil has three main properties that you can use to treat your plants:

  • It is an insecticide and insect repellant; it actually has both these functions. If they ingest it, they feel sick, but the very presence of the oil on a plant keeps them away. It also stops them from laying eggs, so, a thing which is lesser know, it can be used for insect population control.
  • Neem oil is a fungicide; you can therefore use it to treat fungal infections.
  • Neem oil has antibacterial properties; this means that you can use it to keep noxious bacteria away from your plants.

As you can see, it is actually three products in one. This should already make it climb the top of the list of treatments to have for your plants, outperforming most synthetic products.

What Makes Neem Oil Useful For Plants?

The Advantages of Using Neem Oil

Plants contain active ingredients, what chemists technically call “drugs”; these are the active principles of medicines and not only.

Neem stones contain azadirachtin, limonoid, which is also an antifeedant, a substance that stops insects from feeding. Basically, insects and pests cannot eat it, so it protects your plants.

There are at least 200 series of insects that cannot stand neem oil, and possibly even as much as three times this number!

But there is more; neem oil affects the hormones of insectsBecause of this, they will not be able to lay (as many) eggs and reproduce. Stretching it a bit with a metaphor, we may see it as giving insects “early menopause and andropause”.

The damage to the hormone system of the insects that get in touch with neem oil also thwarts their growth.

This is not all; neem oil kills fungithis has been known for millennia in India, in fact, it has been used in Ayurvedic medicine to cure skin fungal infections and other ailments since time immemorial. And it is very effective at that too, especially nail fungus.

Finally, neem oil has antibacterial properties. In fact, it contains some isoprenoids that kill bacteria, in your plants and not only.

This is how it can be used for plants, but you may have grasped that neem oil also has great medical properties for Humans and animals too. But this is not what this article is about.

This may all sound a bit scientific, but don’t worry; while it is only fair that you know why and how a product works, we will now focus on how to use, it, when and how to do it safely.

The Advantages of Using Neem Oil

The Advantages of Using Neem Oil (1)

But why should you use neem oil, when there are so many chemical products on the market?

Some of you have already answered this question, and if it is for the reason I suspect, I agree with you…

But let’s look at the advantages in detail.

  • Neem oil is natural;if this was your reason for choosing it, you have my blessings. This is arguably the most important reason for choosing it, the ethical one.
  • Neem oil is fully biodegradable; ok, this follows from the previous one, but compare it with having substances that stay in your garden, pots and even in the air you breathe for a long time… That’s what you would get with a chemical product.
  • Neem oil can be produced organically; you only need to press the stones to get the oil, so, the environmental impact can be very low indeed.
  • Neem oil does not harm plants; in fact, it is fully metabolized by plants; they absorb it and use it for their own life. No problems with substances that can (and will, even if in the long run) damage your beloved plant.
  • Neem oil is safe; synthetic chemicals can end up affecting your health, that of your children and pets… Neem oil is toxic in comparatively large quantities, but it is safe; we will come to that…
  • Neem oil has many purposes; think about it… with one single product, you can solve many problems. Just get your big bottle and lock it in a cupboard; it will come in handy. This is quite convenient compared with running to the store to buy a specific product for each problem…
  • Neem oil is comparatively cheap; you can get about a liter for $18.

If these advantages don’t convince you, I don’t know what would. Neem oil is becoming very popular because it is an excellent natural solution to many health problems of your plants.

Using Neem Oil: Safety First

Using Neem Oil_ Safety First (1)

We have said that neem oil can be toxic, but only if ingested in substantial quantities. This does not mean that you should regard it as “poison” with the little skull and bone sign.

There are many products we use every day that you can’t ingest… But there are some safety measures you want to use:

  • Keep the bottle of neem oil out of your children’s reach. This goes without saying, of course.
  • Never ingest neem oil; note that there are neem oil products (like capsules) that you can ingest, but pure neem oil is dangerous. When you ingest 20 ml, it can have very serious consequences on you, like vomiting, seizures, acidosis and encephalopathy.
  • Do not spray neem oil on crops before harvesting. Leave three weeks before you harvest. True, neem oil is not as bad as chemicals; it does not enter into your plant and hides there, but a safe time will avoid any problems (even if you are unlikely to ingest big quantities from crops) but, above all, neem oil can be tasted on vegetables and fruit for a few weeks.
  • Wash your hands with soap after using neem oil; you must use soap, as water does not dissolve oils…
  • Don’t apply or spray neem oil on your plants in direct sunlight; wait till the light is dim, as the droplets can act as lenses and cause leaf burn.
  • Aerate after using it or when using it; this is extra precaution, but better safe than sorry. This is not actually necessary, but you may not like the smell.

These, you may notice, are the normal precautions you would need to take not only with synthetic products like pesticides etc., but also with normal home cleaning products like bleach etc.

So, while they may look “scary”, they are not, and remember, unless you swallow it, nothing will happen to you

Is Neem Oil Safe for Pets?

But how about if you have cats, dogs or a gerbil and you want to use neem oil? Here’s the good news: neem oil is not actually toxic and animals will just not touch your plants if they have neem oil on it.

You don’t risk seeing your puppy licking up neem oil from a plant, nor even if you put it in a bowl; there’s no worry on that side.

They will just stir away from it. And they can smell it, don’t worry; breathing it has no adverse effects.

Can You Use Neem Oil for Prevention?

You may be wondering, “But if neem oil keeps insects, bacteria and fungi away, can I just use it on my plants as a form of prevention?” I am pleased to tell you that, yes, you can.

Neem oil will work as a preventive treatment for all the ailments and problems it cures.

So, if you think your Philodendron is at risk of attracting pests, you can spray it with neem oil and the pests will not come.

Similarly, especially with succulents and dry loving plants, indoor conditions are often far too humid for them, and they may risk fungal infections. Give them a little spray of neem oil once in a while and you will keep them safe.

In fact, if you grow plants professionally, especially in a greenhouse, it is not at all a bad idea to give them a little spray of neem oil every month or so to keep them healthy.

How Long Will Neem Oil Last on Your Plants?

How Long Will Neem Oil Last on Your Plants

So, if you use neem oil as prevention, how often should you apply it to keep pests and fungi at bay?

The safe answer is every ten days.The oil will completely coat your plants for about this time, after which, it will start to dissolve.

Of course, this is a general rule, but considering the operation is simple and straightforward, it may be worthwhile, especially of your plants are at risk or if you have a lot at stake.

What Does Neem Oil Quality Depend on?

Neem oil is not all of the same quality, like all products. Good quality neem oil will have a high concentration of active substances, like azadriachtin. But this depends on a few things, including:

  • The plants it comes from.
  • The process used for making it.
  • Whether it is pure or not.

The best quality is obtained by cool pressing the stones. This is the same as with extra virgin olive oil, and with most (maybe all) oils. But this is, of course, more expensive.

Still, the good news is that even fairly low quality neem oil will suffice for most plant problems. Very high quality neem oil is more common for therapeutic uses for Humans.

In fact, look up online for high quality neem oil and you will find treatments for many, many health problem, especially skin problems.

So, you can make do with a fairly good bottle of neem oil at a very decent price for your plants, flowers and crops.

Ways of Using and Applying Neem Oil

Let’s get practical now: are there different ways of applying neem oil, and if so, which are they? The answer is that yes, there is not a single method for using neem oil.

In fact, many gardeners have developed their own methods; they find that by “tweaking” the basic methods they find solutions that work well for them.

So, here are the two key ways of using neem oil:

  • Dabbing it onto affected areas. 
  • Spraying it.

These two methods are different in both the preparation and possible uses for treatment. Still, both are simple and straightforward. Shall we now look at them?

1″: Dabbing Neem Oil on Your Plants

Welcome to the simplest me most straightforward way of using neem oil to treat your plants. This method is more laborious than the next one, but it is so easy and focused that it does have its functions, and we will see which.

Here we go:

  • Pour some neem oil into a bowl or vessel with a wide opening.
  • Take a cloth. Don’t use a sponge or any similar material, as that will soak up most of the neem oil; plus, you will risk making a mess when you squeeze the sponge.
  • Dip the cloth in the neem oil.
  • Gently pass the cloth over your plant.

As you can see, the preparation is simple but if you have many plants to treat, passing the cloth on each leaf, top and bottom, each branch etc can be a rather slow and laborious process.

Nevertheless, this method is very effective if:

  • Only a part of a plant or or some plants are affected. For example, if you spot the beginning of a fungal infection, you can put it to rest by using this method and covering the infected area abundantly.
  • You have a rather urgent treatment to carry out. This method is ideal for advanced (but circumscribed) cases of fungal infections, very stubborn infestations, or to help with rot by killing some of the bacteria that cause it.

On the other hand, this is not a method you can apply to big plants or large gardens or even large parts of gardens of course. Still, in an emergency, don’t be afraid to use it.

What is more, this is certainly not a method you can use as prevention.

You should keep an eye on your plants after applying neem oil this way; this is only to make sure that the plant gets better and to be read it to repeat the operation as necessary.

2: Spraying Neem Oil on Your Plants

Spraying Neem Oil on Your Plants

Spraying neem oil on plants is by far the most common and practical method. However, you cannot spray pure neem oil directly on plants.

Actually, in theory you can, but it’s quite hard to spray oil; it offers a lot of resistance when you spray it and it may not come out uniformly. So, what can you do?

The trick is to melt the neem oil in water, but maintaining all the active substances that neem oil is rich in. But here there’s another problem: neem oil does not mix with water, like all oil.

Oil is fat and fat is hydrophobic, which means that it repels water molecules and does not mix with them. I am sure you have noticed it even with cooking oil…

So, what can we do? Simple, mix it with soap water. By the same principle you use to wash your dishes and glasses, you can mix neem oil with water. And here is how you can go about it:

Preparing Your Neem Oil Spray

  • Warm up 1 liter of water.
  • Melt a small bar of natural soap (like Castile soap). You can do this in many ways; you can heat up the bar on bain-Marie, or grate it into the hot water and allow it to melt. 
  • Stir well.
  • Wait till the water has cooled and reached room temperature.
  • Add a tablespoon of neem oil. You can add more actually; do adjust according to how serious the problem is… But a tablespoon will be enough if you are trying to prevent problems.
  • Take a funnel.
  • Pour the mix into a spray bottle.
  • Shake well.
  • Spray your plants abundantly, trying to reach the most hidden and innermost parts of the plants.

That’s about it. Don’t worry if the mix falls onto the potting soil or on the ground; it is perfectly safe for your plants…

Now, this method may require a slightly longer preparation but it has many advantages:

  • It can be used for large plants, large gardens or groups of plants.
  • The application is very quick.
  • It is cheap, as you will need little neem oil for a lot of plants.
  • It is easy to cover whole plants; dabbing is fidgety and there may be areas you can’t reach. By spraying, you will make your life easier.
  • The soap itself makes life harder to some pests; yes, many insects need to stick to the plant to “feast” on it; soap makes it hard for them to have a good grip, and they slide off…
  • It is excellent for prevention.

If you use this method, make sure you are easy to apply the spray after 10 days or so. The neem oil will have vanished, dissolved and disappeared at about that time…

So, as you can see, neem oil is very easy to use, and it has no downsides at all…

Neem Oil: Is It the “Miracle Cure” for Your Plants?

From what you have read, you may be excused if you believe than neem oil is like a panacea, a miracle cure for most of your plants’ problems. But is it so?

Well, like many organic remedies it is becoming more and more popular by the day… The reason is of course that you don’t need to handle synthetic chemicals, nor will you be dispersing them into the environment if you use the oil of this beautiful plant.

But there is more, it is very easy to use, it is widely available, safe, and – let’s not forget – it treats an awful lot of problems and ailments your plants may have, and it prevents them too!

Still, it does not treat all ailments and health issues;there are some that even neem oil cannot solve, like root rot, some very stubborn pests etc. Having said this, I think it will be hard, in a few years, to find neem oil missing from the cupboard of any organic gardener…

But one thing can treat your plants better than neem oil, yes, and that one is actually free: it is simply called love and tender loving care…

Updated on by Amber Noyes

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