Ants in the garden are a puzzle, because they are both useful and troublesome at the same time. They aerate the soil, eat the eggs of pests, and clean up dead insects. They also farm aphids, protecting them from predators in exchange for honeydew, and a colony that is farming aphids on your roses can make an aphid problem far worse than it would otherwise be. They undermine paving, nest in pots, and bite if disturbed. The question is rarely whether to get rid of ants entirely — it is whether the ants in your garden are helping or harming, and what to do about it if they are harming.
This guide explains how to tell what the ants are doing, when they are a problem, and organic-first control in order — starting with the aphids they farm, then barriers, then least-toxic options. If the ants are farming aphids, the aphid guides are the place to start: see our aphids on roses and aphids on peppers guides.
How to identify ants
Garden ants are small, usually 2–5 mm long, dark brown or black, with a narrow waist, elbowed antennae and six legs. They live in colonies in the soil, under paving, in pots and in lawns, and they follow well-worn trails to food. The most common garden species are small and dark, and they are active in the day, especially in warm weather. Winged ants appear in summer, when the colony produces flying males and queens — a swarm of flying ants is alarming but harmless, and it lasts only a day or two.
Ants are sometimes confused with termites, but termites are pale, have straight antennae and a thick waist, and are rarely seen above ground in the garden. If the insect is dark, has a narrow waist and elbowed antennae, and is walking in a trail, it is an ant.
What ants actually do
Ants are generalists. They eat dead insects, the eggs of pests, seeds and honeydew, and they move soil as they dig their nests, which aerates it. They also farm aphids: they stroke the aphids with their antennae to encourage them to release honeydew, a sweet liquid the ants eat, and in exchange they protect the aphids from ladybirds, lacewings and other predators. This is the main way ants harm a garden — not by eating plants themselves, but by protecting the aphids that do.
Ants rarely eat plants directly, though they can damage seedlings by undermining the soil around the roots, and they can hollow out a strawberry or a soft fruit to reach the sweet flesh inside. They nest in pots, where their tunnelling dries the compost out and disturbs the roots, and they undermine paving slabs, causing them to sink. They also bite if a nest is disturbed, though garden ants are not dangerous.
A small number of ants is not a problem worth solving. They are part of the garden's food web, and a garden without ants would have more of some pests, not fewer. Act when you see ants farming aphids on a valued plant, when they are nesting in pots, or when they are undermining paving.
Organic-first control, in order
1. Inspect first. Follow the ant trails and find the nest. Look for aphids on the plants above the trails — if the ants are farming aphids, the aphids are the problem to solve first. Check pots for nesting, and check paving for undermining. Note which plants are affected and how many ants there are.
2. Deal with the aphids. This is the most important step, and the one most gardeners miss. If you remove the aphids, the ants lose their reason to be on the plant. Blast aphids off with a strong jet of water, hand-pick them, or encourage ladybirds and lacewings. See our aphids on roses guide for the full method. Once the aphids are gone, the ants usually leave the plant alone.
3. Barriers. Sticky bands around the trunk of a fruit tree or the stem of a valued plant stop ants climbing up to farm aphids. Apply the band in early spring, before the aphids arrive, and check it regularly — it needs replacing when it becomes clogged with dust or insects. For pots, stand the pot in a saucer of water to create a moat the ants cannot cross, or move the pot to a new position. For seedlings, a ring of diatomaceous earth around the base can deter ants in dry weather.
4. Traps. Bait traps can reduce a colony, but they work slowly and they are not selective — they may also attract other insects. If you use them, place them along the ant trails, away from children and pets, and follow the label. They are a supplement to dealing with the aphids, not a replacement.
5. Beneficial insects and birds. Ants are eaten by birds, ground beetles and other predators, and a garden with plenty of ground cover and bird activity supports them. Avoid broad-spectrum sprays, which kill the predators faster than they kill the ants, and which also kill the ladybirds and lacewings that would otherwise eat the aphids.
6. Least-toxic options last. Diatomaceous earth dusted on the nest entrance and along trails can reduce numbers in dry weather, but it needs reapplying after rain. Boiling water poured on a nest is sometimes suggested, but it kills soil life as well as ants and it rarely reaches the queen, so the colony usually recovers. Insecticidal soap sprayed directly on ants kills them on contact, but it does not reach the nest. Always check your local extension service for products approved in your area, and remember that wiping out a colony entirely is rarely necessary — and often counterproductive, since a new colony will move in.
Prevention
Prevention is about the aphids and the nesting sites. Keep plants healthy and well watered, since stressed plants attract aphids, and check roses and other aphid-prone plants weekly from spring onward. Remove dead wood and debris where ants nest, and keep pots raised off the ground on feet so ants are less likely to nest in them. Seal gaps in paving and keep the edges tidy. Grow roses and other aphid-prone plants where you can reach them easily for inspection, and plant marigolds and other flowers nearby to attract the ladybirds and lacewings that eat aphids. A garden with a good population of aphid predators will have fewer aphids, and therefore fewer ants farming them.
Frequently asked questions
Do ants damage plants? Rarely directly. The main harm is indirect: they farm and protect aphids, which damage plants. They can also undermine seedlings and nest in pots, drying the compost out. Deal with the aphids first, and the ant problem usually fades.
Should I get rid of all the ants in my garden? No. Ants are part of the garden's food web — they eat pest eggs, aerate the soil and clean up dead insects. A garden without ants would have more of some pests, not fewer. Control them where they are causing a problem, and leave them alone elsewhere.
How do I get ants out of a plant pot? Stand the pot in a bucket of water for half an hour so the compost is soaked through — the ants will leave. Then move the pot to a new position and stand it on feet so ants are less likely to nest in it again. Check the plant for aphids, since ants often nest in pots that have aphids above.
Why are there ants on my roses? They are almost certainly farming aphids. Check the stems and buds for clusters of small green, black or pink insects — those are the aphids. Remove the aphids and the ants will leave. See our aphids on roses guide for the method.
Do ant repellents work? Scent repellents and diatomaceous earth can reduce ant activity in a small area, but they need reapplying and they do not reach the nest. They are a supplement to dealing with the aphids and proofing the plants, not a replacement — and check your local extension service for products approved in your area.
Ants are a pest where the real problem is usually something else. Find the aphids, deal with them, put a sticky band on the trunk, and keep the pots raised — and the ants will go back to being a useful part of the garden. For the aphids themselves, see our aphids on roses and aphids on peppers guides, and for general help use the pest identifier helper.