Ants are common on indoor and outdoor plants. While they rarely eat foliage, their presence signals an underlying issue that requires attention. Natural, non-toxic methods can effectively remove them and prevent their return. This approach focuses on addressing the root cause of the infestation using simple physical and barrier techniques.
Understanding the Ant-Plant Relationship
The primary reason ants congregate on plants is to harvest honeydew, a sweet substance excreted by sap-sucking pests. These pests include aphids, mealybugs, and scale insects, which feed on the plant’s vascular tissue. Honeydew is a sugary waste product that ants use as a carbohydrate source for their colony.
This dynamic creates a mutualistic relationship often called “ant farming.” The ants actively protect these honeydew-producing pests from natural predators like ladybugs and lacewings, guaranteeing their food supply. They may even move pests to new parts of the plant to encourage better feeding. To remove the ants permanently, you must first eliminate the secondary pest infestation drawing them to the plant.
Direct Physical Removal Techniques
The quickest first step is physically dislodging the ants and the pests they are farming. A strong, targeted blast of water is highly effective for immediate removal. For durable outdoor plants, use a garden hose to spray infested areas, focusing on the undersides of leaves where pests hide.
For indoor or delicate plants, use a kitchen sink sprayer or shower for a gentler stream. The water washes away both ants and soft-bodied pests like aphids. If a stem or leaf is heavily colonized and damaged, pruning that section immediately reduces the total pest population. You can also use a soft, damp cloth or cotton swab to gently wipe honeydew and pests directly off tougher leaves.
Topical and Barrier Treatments
Once the immediate population is reduced, topical treatments eliminate remaining pests and deter new ants. A simple insecticidal soap spray can be made by mixing mild liquid dish soap (which acts as a surfactant) with water. A common formula is 2.5 tablespoons of mild liquid soap and 2.5 tablespoons of vegetable oil mixed into one gallon of warm water. The soap’s fatty acids break down the waxy outer layer of soft-bodied insects, causing dehydration and death upon contact.
Before treating the entire plant, test the solution on a single leaf for 24 hours to ensure the plant is not sensitive, preventing leaf burn. Apply the spray thoroughly, covering all leaf surfaces, and reapply every few days until the pest population is controlled.
To create a physical barrier, use Diatomaceous Earth (DE), an organic powder made of fossilized diatoms. These microscopic, sharp edges cut the exoskeletons of insects like ants as they walk over it, causing dehydration. Sprinkle a thin layer of DE around the rim of the pot or the base of the plant. Ensure it remains dry to be effective, reapplying after watering or rain.
Strong scents also disrupt ant trails and serve as natural repellents.
Natural Repellents
- Sprinkle kitchen ingredients like ground cinnamon or coffee grounds around the base of the plant container.
- Spray a few drops of peppermint oil or citrus oil mixed with water around the perimeter to mask the pheromone trails ants use for navigation.
Targeting the Colony for Long-Term Control
For a lasting solution, disrupt the entire ant colony, not just the foraging workers on the plant. Identify the location of the nest by following the ant trail; the nest may be in the soil of a potted plant or nearby ground.
One effective strategy is redirecting ant movement using strong-smelling substances. A simple solution of equal parts white vinegar and water can be sprayed along established ant paths to erase the chemical pheromone trail. This confusion forces ants to re-establish a route, often leading them to abandon the current food source.
A highly effective long-term method uses a slow-acting, natural bait that worker ants carry back to the colony, eliminating the queen. A common bait recipe is a mixture of one part borax to three or four parts sugar, dissolved in warm water to create a syrup. This bait must be placed in a secure container, such as a jar with small holes, positioned well away from the plant, children, and pets. The sugar attracts the ants, and the borax acts as a stomach poison distributed throughout the nest, providing source control.