Horticulturalists don’t categorize ants as garden pests, because they don't actively damage plants nor do they transmit any diseases around the garden. In fact, there are some benefits to garden ants.
Still, many people still consider ants unwelcome in the garden. Some can be aggressive enough to inflict painful bites, especially the notorious fire ant of the South, which seems to expand its territory northward year by year. And there are other reasons why you might prefer an ant-free garden. But before bringing out toxic chemicals, consider whether the problems posed by ants outweigh the benefits.
Problems Caused by Ants in the Garden
Some ants maintain a mutually beneficial relationship with aphids, which are indeed damaging to plants. As the tiny aphids feed on plant juices, they produce a sweet byproduct known as honeydew, which the ants crave as food. In exchange, ants care for and protect the aphids from predators and parasites; they essentially "farm" the aphids. A struggling plant is sometimes blamed on the ants covering, but they are usually a secondary guilty party. Look closely and you'll probably see lots of aphids.
Ants can also ruin the aesthetic of cut flowers—such as an otherwise perfect spring bouquet of peonies. Finally, ground-nesting ants can sometimes undermine the soil to a degree that a specimen shrub's root system can be compromised, or extensive ant tunnels can hasten erosion. So there are some legitimate reasons why you might want to get rid of these otherwise harmless insects. Before you do though, consider the benefits.
Benefits of Ants in the Garden
Ants do have several virtues in the garden:
- Ants are natural predators that eat the eggs and larvae of some damaging pests.
- Ants are pollinators. This role has become increasingly important as other pollinators have been threatened. Ants transfer pollen as they march from plant to plant.
- Ants aerate the soil by digging tunnels. Especially in dense soils, ant tunnels help transport air, water, and nutrients to plant roots.
For the most part, the tiny garden ants, red or black in color, are relatively harmless in the garden, while the larger carpenter ants of fire ants pose a more real risk. But if the problems outweigh the benefits for you, there are several methods for ridding your flower garden of ants.
6 Ways to Get Rid of Ants
Create a Homemade Ant Repellant
Ants are very sensitive to odors, as any picnicker can tell you. Just as they are attracted to sweets, certain smells repel them. Experiment with cotton balls soaked in ant-repelling essential oils. Ants detest mint, camphor, tansy, and clove oil.
Another method is to place hot peppers in a blender with a bit of water to create a dense mash, which you can spread in problem areas. Faced with this odor, ants are likely to vacate the area. This homemade remedy also works as a preventive repellant.
Use Borax Bait
Baits laden with an insecticide are more likely to target just the ants without harming other insects. You can mix a cup of borax with a cup of honey or jelly and place it near an area of ant activity. Ants will feed and carry this toxic mixture back to their queen, which will result in the death of the entire colony.
You must be patient to see the results of this method, as borax is a slow-acting poison, and it requires time for the workers to distribute the toxin throughout the colony. If this homemade solution is too messy, you can purchase ready-made boric acid ant bait.
Be careful with using borax or boric acid where pets or wild animals can access it. These substances are mildly toxic to animals. Borax will also kill spiders, but it doesn't harm most beneficial insects.
The same pesticides that kill ants are also toxic to many insects that gardeners want around the flowerbed, like Monarch butterflies caterpillars and ladybugs. Avoid traditional spray pesticides unless you can carefully target the ant colony.
Bait Ants With Baking Soda
Like borax, baking soda is toxic to ants, and it is less poisonous to other animals. Mix a 50-50 concoction of powdered sugar and baking soda and place it near the ant colony. Although the mixture is harmless to most animals, they will be attracted to the sugary mixture, requiring you to reapply the bait regularly.
Use Sticky Traps
Ants are attracted to sweet foods, and this includes many fruits and some nectar-rich flowers. Peonies, in particular, seem to attract ants just as buds turn to blossoms. Although ants rarely inflict damage to flowers or fruits, no gardener wants to mar the joy of harvest with a handful of swarming ants.
You can use sticky traps to prevent ants from ascending the plant of concern. Buy a commercial sticky product, such as Tanglefoot, or make your own sticky traps from adhesive paper strips wrapped around the base of the plants.
Combat the Aphids
If you notice a congregation of ants gathering on one of your garden specimens, be suspicious. Ants are purposeful creatures, not given to leisurely gatherings. Look closely, and use a magnifying glass if necessary. You will probably discover an infestation of aphids.
The ants are enjoying the sweet honeydew excreted by the aphids. In exchange for this nourishment, the ants protect the aphids from their enemies, attacking such beneficial insects as ladybugs. You must treat the plant-damaging aphids first; the ants will then seek food elsewhere.
Treat Fire Ants as an Emergency
Fire ants deserve less of the flower gardener’s tolerance and sympathy. These aggressive invaders can crawl quickly up the gardener’s arm or leg, delivering dozens of painful bites before the victim detects them. They also prey on wildlife, such as lizards, frogs, spiders, and even birds in the garden.
If you have any fire ant mounds on your property, you must destroy them. Cover the mound with a container, and pour boiling water around the container. Wait one minute, then turn over the container with a stick and pour an additional gallon of boiling water into the ants seeking refuge in the container. Repeat as necessary.
A deluge of ordinary household vinegar will also dispatch an ant colony instantly, though it can also acidify the soil unless you immediately drench the area with water. Fire ants require this kind of emergency treatment with boiling water or vinegar, but a colony of carpenter ants should also be treated seriously, especially if it is near your house.
What Causes Ants in the Garden?
Sometimes the very things we use to care for our gardens have the unfortunate side effect of drawing ants. The compost pile you nourish attracts ants when it sends the sweet aroma of rotting cantaloupe rinds and banana peels into the air. To discourage ants, maintain a hot compost pile, using the proper ratio of green and brown ingredients. An elevated compost tumbler can also prevent ant infestations.
A thick layer of wood chip mulch is important for weed suppression and moisture retention in the garden but also creates a cozy habitat for many ant species. If this makes you dread digging in the soil for fear of unearthing a swarm of angry ants, try an inorganic mulch like crushed rocks, ground-up tires, or synthetic landscape fabric. These materials won't enrich the soil, though, so you may still want to add compost or manure at planting time.
How to Prevent Ants in the Garden
It's fairly hard to ant-proof your entire garden, but specific plants can often be protected by spraying them with a citrus-based horticultural oil. The oil is toxic to ants, and its smell destroys their scent trails and often sends them away. Even a simple 50-50 mixture of lemon juice and water will likely repel ants.
Keeping the ground fairly clean of fallen flowers and other debris will also eliminate the habitat that favors ants.
Do Garden Ants Fly?
As with all ant species, garden ants in the reproductive stage are flying insects. The common black garden ant usually takes wing to mate in the fall. These are quite small insects, however, so you may not recognize them as ants unless you see them emerging from ground tunnels.
How Long Do Garden Ants Live?
Worker ants can live as long as four years, but queens have been known to live for 15 years or longer if the colony remains undisturbed.
Do Garden Ants Bite?
All ants are capable of biting, but the typical red and black garden ants are small creatures that generally don't bite unless you accidentally touch them. The bite can be momentarily painful, but usually simply leads to an itch. These ants do not sting in the ferocious way that fire ants do, hence there is no real reason to fear them.
Are There Any Plants That Repel Ants?
Some fragrant herbs tend to repel ants. Mint, lavender, and rosemary are among the plants known to keep ants away. Plant some of these in your garden and ants are less likely to be a problem.
Aphids. Entomology at the University of Kentucky.
How to control invasive pests while protecting pollinators and other beneficial insects. Michigan State University.