How To Keep Ants Out Of Garden Naturally

Some gardeners must hate ants because they are constantly talking about natural ways to get rid of them in the garden. If you thought home remedies are popular for things like slugs or weeds, it doesn't compare to the number of solutions available for getting rid of ants naturally.

A lot of research has been done on fire ants, and for good reason. They bite and sting and their sting is painful.

What does the science tell us about controlling ants outside? Let's have a closer look at natural home remedies for getting rid of ants.

How to Get Rid of Ants Naturally, In the Garden

How to Get Rid of Ants Naturally, In the Garden, photo by Brian Mai

Ants in the Garden

Before I look at how to get rid of them, lets understand the problem they cause in the garden.

For the most part ants are not a problem in the garden. They don't eat plants, except in very dry locations. Sure, you might find them on a half eaten strawberry but something else took a bit out that strawberry and the ant is just sucking up some of the left over juices.

When they make a nest they add a lot of air to the soil, which can raise the height of the soil. This can be a problem when trying to mow the lawn, but in most cases that is a minor inconvenience.

Ants even fertilize your plants. It has now been shown that ant excrement provides the plant with nutrients.

Fire ants do bite and sting. It certainly makes sense getting rid of these and nobody wants ants in the home.

Garden Myths book by Robert Pavlis

Ants can harm plants if they build their nest right under smaller plants, or under plants whose roots can't tolerate the extra air and dry conditions of the ant nest. They can be a problem in rock gardens. The ants like the sandy soil of these gardens and the plants are so small that it doesn't take much to kill them.

You can also find ants on plants that have aphids. The ants actually farm the aphids and get honeydew from them. The ant is not really the problem, it's the aphids. Get rid of the aphids and the ants usually leave the plant alone.

Ants are also very valuable for the garden. They collect a lot of dead insects and they aerate the soil. To better understand the value of ants in the garden see Secrets of a Super Organism.

Soil Science for Gardeners book by Robert Pavlis

For the most part, ants are not a big problem but for some reason gardeners want to get rid of them. You have to understand that this is impossible. If you kill the ants in your garden, or chase them away, other ants will simply find your garden and start living there. Getting rid of ants is never going to happen and with the except of fire ants, you might as well learn to live with them.

Ants Are Not Just Ants

That heading is not exactly true, ants are ants, but there are many different kinds of ants. There are some 22,000 species , and yet when people talk about home remedies to get rid of ants, they rarely mention the type of ant being controlled. A certain concoction may actually work on a certain type of ant but without full details, anecdotal reports are mostly meaningless.

Fire ants are frequently mentioned, but in at least one online discussion any red ant was considered to be a fire ant, which is not true. How many gardeners can actually identify a fire ant? I can't.

Building Natural Ponds book, by Robert Pavlis

I live in zone 5, Ontario, and have always thought fire ants only occurred in warmer zones, like the southern US. It turns out that even in Ontario we have fire ants, but they are not the same fire ant found in the southern US or is this just a myth? More on this in another post.

Why is all this important?

Except for scientific studies and government reports, the type of ant is rarely mentioned. We can't assume that a remedy for one type of ant works on all other types. That makes it hard for me to reach any conclusions in this review. If I know the type of ant being discussed, I will mention it. If not, I'll just call them ants. Any testing that has been done has only been done on a few species.

Natural Home Remedies for Ants

In just one Facebook Group discussion, 20 different home remedies for ants were mentioned. Not one of them had supporting evidence to show they worked. Here is the list.

cornmeal
dish soap
coffee grounds
nematodes
peppermint oil
diatomaceous earth
cinnamon
boiling motor oil
vinegar
bay leaf
chalk dust
marigolds
cedar mulch
salt
baking soda
corn starch
plant chives
plant garlic
boiling water
cucumber rinds

Some of these will just chase ants out of your garden and others will actually kill them, or so it is claimed.

You will have no problem finding someone who has used one of the above remedies and swears it works, even though most do not work. Why is that?

In some cases the ants move a few feet away to a spot that is less visible and the gardener thinks they're gone. Some ants have multiple entrances into their nest. If you fiddle with one opening, or place something there that they don't like, they just fool you and use another entrance.

It is virtually impossible for a home owner to confirm that the ants in a nest are killed, but they claim it all the time. Seeing some dead ants proves nothing. You have to kill all of the queens to kill the nest. Good luck proving that.

Does Diatomaceous Earth Kill Ants?

Diatomaceous earth (DE) is the skeletal remains of marine diatoms. They are abrasive and have a drying ability. It is this drying ability that makes them dangerous to insects. Insects stay hydrated by excreting waxy material onto their bodies. The DE absorbs these materials, the insect dries out and dies.

One of the problems with DE is that it is only works when dry. If it gets wet, it no longer works. If wet DE dries out, it becomes active again.

For DE to work, you need to put it in a location where the ants come into contact with it. Dusting it into nest openings works well. Ants then carry it deeper into the nest where it affects other ants.

Does DE work on fire ants? "Horticultural-type DE applied to mounds as a dust or water suspension may move ant colonies, but probably not eliminate them." DE kills some ants, but not all of the ants in a nest.

Does Borax Kill Ants?

Borax is quite toxic to ants. They can't smell it or taste it. When it is mixed with sugar, the ants take it back to the nest along with the sugar, feed it to the larvae and queen. Over time they die from boron poisoning.

Borax is also used as the active ingredient in various commercial ant products.

There are numerous home remedies being promoted and some are quite complex and include other ingredients which are completely unnecessary. The simplest formula is to mix borax and sugar 50/50 and place it near a nest. You can also dissolve that in water if you want a liquid form. Some formulas use less borax.

Borax contains boron, an element that is toxic to both plants and animals and putting too much in the soil near plants can kill them. Borax has been used for many years as a cleaning agent, so it is relatively safe for humans, but make sure you, your children or pets don't eat it.

Does Cornmeal Kill Ants?

The claim goes like this. Put cornmeal near the nest. Ants will eat the cornmeal and once it's inside their stomach it absorbs water, expands and the ants blow up.

Cool story – but complete nonsense.

To start with, adult ants do not eat solid food. They would never eat cornmeal. Besides, cornmeal will not blow up any insect, not even slugs.

The ants might pick up some cornmeal and take it into the nest to feed larvae who can eat solid food. The larvae then regurgitate digested cornmeal in liquid form, which the adults eat. Cornmeal is actually good food for ants.

How did this myth start? I'm just guessing, but cornmeal is frequently used in chemical ant baits. The ants love corn, so they take the cornmeal, along with the pesticide, back to their nest. The pesticide then kills them.

Imagine the ants in their nest, sitting by a cozy fireplace, laughing their heads off at the human gardeners who keep feeding them cornmeal.

Will Nematodes Kill Ants?

There are commercial products which contain nematodes (Steinernema carpocapsae, or Steinernema feltiae) and claim to "attack and kill young ant larvae in nests and repel adult ants from building new nests in treated areas. "

The University of Florida, Extension Office, has this to say, "they have not proven effective for actually reducing fire ant populations or fire ant colonies in the field. We are not aware of any credible scientific evidence that documents any nematode species to be efficient for controlling imported fire ant colonies. These nematodes are able to kill individual ants in the laboratory, but in field trials the ant colonies usually respond to nematodes by moving, sometimes splitting colonies in the process." When tested in nursery pots, the nematode was ineffective at controlling fire ants and this report concluded that, "Strains tested to date caused ants in treated mounds to temporarily move away from the treated mound, but few colonies were actually eliminated. "

I contacted two companies that sell such products and asked them for research that supported their claims. One never responded and the other had this to say, "this product does not kill the ants. It irritates them, so they move away. Unfortunately how far away is unknown until you have made your first application and repeat applications are needed every four weeks until the ants are gone", but provided no research.

There seems to be very little testing of nematodes for ant control, and the suppliers of products provide no research to support their claims. None of the Integrated Pest Management (IPM) procedures for ants even mentions the use of nematodes.

To apply nematodes, you need to water them in. This works fine for grubs that live right below the sod layer, but trying to water them in so that they get to the bottom of an ant nest is just not very likely.

Will Boiling Water Kill Ants?

Many people claim that pouring boiling water onto an ant nest will kill them. The truth is that ant nests can go very deep in the ground, as much as 6 ft (2 m) for fire ants. At the first disturbance to a nest, the queen is moved lower in the nest. Unless the boiling water reaches her, and kills her, the nest will survive.

Here is what the experts say about using boiling water on fire ants, "1-2 gallons of very hot to boiling water will kill FRESH fire ant mounds 60% of the time. Be careful not to cook plants!" The University of Florida says, "Scalding water (190ºF-212ºF) has been used on mounds (fire ants) with an elimination success rate of 20%-60%. Slowly pour at least 3 gallons onto the mound, being careful to avoid getting burned. A mound may need several treatments to reach and kill the queen and brood. Hot water may injure plants near the mound."

It works some of the time, on new nests, but you need to use a lot of water.

As ant nests get older, they get larger and deeper, and then boiling water becomes less effective and it's only an option when the nest is not near plants.

Coffee Grounds and Ants

Both my own experiments and that of Dr. Wizzie Brown, an entomologist at Texas AgriLife Extension show that coffee grounds do not affect ants.

Does Mint Kill Ants?

Ants crawling all over mint leaves

Mint and other aromatic herbs are frequently recommended for controlling ants.

Gardeners have reported ant hills being built right under their mint plants – I think that is very telling. I have also looked at the effect of mint on ants in more detail and found absolutely no effect. In fact, ants seem to enjoy walking all over the mint.

What About Cinnamon Ant Control?

Cinnamon treats all kinds of pests and I have done a complete report on its antifungal properties and discovered most people don't buy the "real' cinnamon. You can read more here: Cinnamon – Does it Stop Damping Off in Seedlings?

Dr. Wizzie Brown, an entomologist at Texas AgriLife Extension has also tested cinnamon on fire ants and found no effect.

Cinnamon essential oil was tested and found to not only repel ants, but to also kill them, which may have led some gardeners to assume cinnamon works. This kind of incorrect use of scientific results is common. The research only looked at essential oils, a very concentrated form of cinnamon and all of this work was done in the lab. No field tests were done. This research, although interesting, tells us nothing about how cinnamon powder works in the field.

Ants and Essential Oils

Essential oils are extracts from plants that contain various chemicals in a concentrated form. The attraction for using these is that they are natural, and probably less toxic to humans than other pesticides.

Studies have found that various oils slow down the feeding behavior of fire ants, or reduce the number of workers sent to food, however, these effects are short lived and they don't cause the colony to move or to die out.

A lab study of Argentine ants found that essential oils did deter ants, but the effect was short lived.

It would be incorrect to assume that the plants from which these oils are extracted have any effect on ants.

Peppermint oil was one of the solutions proposed on Facebook, but no formula for application was given. Testing has shown that a 1% solution may deter ants, but it needs to be applied weekly.

Citrus oil extract has also been shown to work as a nest drench (1.5 fl oz Orange Oil and 3 fl oz Dawn® Soap/ gal water per mound ).

Can Aspartame Control Ants?

The legend says that if you put some sweetener containing aspartame on the nest it will kill the ants (thanks to the Laidback Gardener for this one).

In 2006, Spoof News posted an article detailing the toxicity of aspartame on ants. The title was, FDA Certifies Aspartame as Ant Poison, and goes on to say, "That crap (aspartame) kills ants dead. It works on carpenter ants, silverfish, roaches, and almost anything in fact."

The article ended with, "The story above is a satire or parody. It is entirely fictitious", but that did not stop the internet gods from spreading the myth and numerous sites and newspapers still claim that aspartame kills ants.

The mythical articles that developed from this spoof are quite entertaining – if it was not so sad. Here is a glimpse at what one said.

How does it Work: Aspartame is a neuropoison. It most likely kills the ants by interfering with their nervous system. It could be direct, like stopping their heart, or something more subtle like killing their sense of taste so they can't figure out what is eatable, or smell, so they can't follow their trails, or mis-identify their colonies members, so they start fighting each other. Not sure what causes them to end up dying, just know that for many species of ants it will kill them quickly and effectively.

None of the information in this paragraph was in the original spoof – it is all made up nonsense. Aspartame does not kill or deter ants.

Ever Wonder What an Ant Nest Looks Like?

Things That Don't Control Ants

People seem to just make stuff up, or they hear some facts and interpret them incorrectly. The net result is that most home remedies don't work and that also goes for DIY ant control. None of these have any scientific support: dish soap, vinegar, bay leaf, chalk dust, marigolds, cedar mulch, salt, baking soda, corn starch, chives, garlic, cucumber rinds, club soda, wood ashes, shoveling ants from two nest together. If you find some scientific support for these, let me know in the comments.

How To Control Ants

What does work?

Step one is to decide if ants are really a problem. It is unlikely that you will get rid of them in the garden.

If they do need to be controlled, the following work to some extent.

Diatomaceous Earth
Borax
Peppermint Oil
Citrus oil

What about commercial products? The University of Florida had this to say, "Commercially available organic products that contain ingredients such as boric acid or diatomaceous earth can kill ants, but their effectiveness to kill whole colonies has not been consistently demonstrated."

In each case, these treatments need to be repeated each time new ants come to your garden. Nothing keeps ants out of the garden, except maybe an anteater.