Ants on your houseplants are rarely the real problem. More often, they are a tell-tale sign that something else is lurking among the leaves.
Unlike some pests, ants do not feed on healthy plant tissue. Instead, they are attracted to the sweet, sticky honeydew produced by sap-sucking pests such as aphids, scale and mealybugs. If you spot ants marching up and down your plant, there is a good chance they have found a rather convenient food source.
So, before you reach for the ant killer, it is worth investigating what has attracted them in the first place. Find out why ants appear on houseplants, which pests they could be pointing towards, and how to tackle the problem at its source.
What Are Houseplant Ants?
The ants you find indoors are usually common garden ants, around 3 to 5mm long, black or dark brown, foraging for food and moisture. They are not a houseplant-specific pest. They come inside looking for sugar and water, and a pot of moist compost with a honeydew-producing infestation offers both.
Why Ants Appear on Houseplants
There are three main reasons ants take an interest in a pot.
They are farming honeydew
Aphids, soft scale, mealybugs and whitefly all excrete a sticky, sugary residue as they feed. Ants harvest this and will actively protect the pests that produce it, even moving them to fresh growth. If you see ants, check the undersides of leaves and the stem joints for these pests. Our notes on treating mealybugs and getting rid of scale cover the usual culprits.
The compost is a good nest site
Warm, undisturbed, occasionally moist potting compost is close to ideal for a small ant colony, especially if the plant is not watered often. You may see loose soil pushed up at the surface or ants streaming from the drainage holes.
They followed a sugar trail indoors
Sometimes the plant is simply on the route between an outdoor nest and a kitchen. That sticky residue you can feel on the leaves is the giveaway. Our guide to sticky residue on houseplants explains what to look for.
The Damage Ants Cause
Ants themselves do little direct harm to a houseplant. The problems are indirect but real:
- They protect and spread sap-sucking pests, letting a small aphid or mealybug problem become a large one.
- The honeydew they farm feeds sooty mould, a black fungal film that coats leaves and blocks light.
- A colony nesting in the pot disturbs roots and creates air pockets, so water runs straight through without wetting the compost.
How to Get Rid of Ants on Houseplants
Immediate Steps
Isolate the affected plant away from the rest of your collection so nothing spreads. Wipe down the leaves and stems with a damp cloth to remove honeydew and any pests you can see. If you suspect a nest in the pot, the most reliable fix is to submerge the pot in a bucket of room-temperature water for 15 to 20 minutes. The ants will float out or leave. Let the pot drain fully afterwards.
Deal With the Pest They Are Farming
You will not clear the ants for good until you clear the honeydew source. Treat the underlying aphids, scale or mealybugs directly. A plant-safe contact spray such as BioBizz Leaf Coat physically coats and smothers soft-bodied pests, and for a stubborn infestation Provanto Ultimate Bug Killer gives longer control. Repeat every 7 days until both the pests and the ants lose interest.
Natural Deterrents
Ants navigate by scent trails, so disrupting the trail helps. Wiping surfaces near the plant removes the pheromone path. A few neem leaves tucked into the top of the pot are a traditional, gentle deterrent, and letting the top few centimetres of compost dry out makes the pot a far less attractive nest site. You will find our full pest range in the fungal and pest control collection.
Preventing Ants From Coming Back
Prevention is mostly about denying them food and a home. Check new plants for sap-sucking pests before they join your collection, and quarantine anything you are unsure about. Do not let plants sit permanently wet, since a soggy pot and a honeydew infestation are the two things ants want most. Clean up any sticky residue promptly so sooty mould and ant trails have nothing to work with. If a colony keeps returning to the same pot, a full repot into fresh compost is the cleanest reset. If fungus gnats are also in the mix, our guide to fungus gnats in potting soil pairs well with this one, since both thrive in wet compost.