Ants nesting in soil are a nuisance, whether tunneling through lawns, raising mounds in gardens, or inhabiting potted plants. While not always directly harmful, their tunneling disrupts delicate root systems and causes soil to dry out prematurely. Furthermore, ants often protect sap-sucking pests like aphids and scale insects, farming them for sugary honeydew, which indirectly causes plant damage. Addressing an ant problem requires selecting a method that penetrates the colony effectively while minimizing harm to the surrounding environment.
Natural and Physical Removal Techniques
Non-synthetic methods focus on physically eliminating the colony or creating an environment inhospitable for the ants. One direct approach for garden mounds is slow drenching of the nest with a large volume of very hot water. This technique can eliminate a significant portion of the colony, including the queen, but must be applied with caution to avoid scalding the roots of nearby plants.
Diatomaceous Earth (DE) is a naturally occurring powder made from the fossilized remains of tiny aquatic organisms. DE works as a mechanical insecticide; its microscopic, sharp edges abrade the ant’s waxy exoskeleton upon contact. This physical damage leads to fatal dehydration over 24 to 48 hours, but the powder must remain dry to maintain effectiveness.
For nests near plant bases, a drench using insecticidal soap or horticultural oil can be applied directly to the colony entry points. These solutions kill ants on contact by dissolving their outer cuticle and blocking respiratory openings, leading to suffocation. A targeted application ensures the solution reaches deep into the nest channels. Alternatively, repeatedly disturbing the nest by digging or flooding can encourage the colony to relocate.
Using Targeted Baits and Insecticides
Chemical controls target the colony’s reproductive center, offering an effective solution for large or persistent colonies. The most successful method uses ant baits, formulated with a slow-acting poison mixed with an attractive food source like sugar or protein. The slow action allows foraging worker ants to consume the bait and carry it back to the nest before succumbing.
The contaminated food is shared with the queen and larvae through trophallaxis, the mutual exchange of liquid food between colony members. Poisoning the queen halts the colony’s ability to produce new workers, leading to the eventual collapse of the entire nest over several days to a week. Baits are preferred for soil infestations because they eliminate the source of the problem, unlike contact sprays that only kill visible foraging ants.
For immediate control of visible mounds, contact insecticides in the form of dusts or granules can be applied directly to the nest opening. These products, often containing pyrethroids, kill ants by disrupting their nervous systems as they walk through the treated area. When using any chemical product, follow all label instructions carefully and take precautions to prevent environmental contamination, such as avoiding application near water sources. Always wear appropriate protective equipment and keep children and pets away from treated areas until the product has settled or dried.
Treating Potted Plants Versus Garden Beds
The contained volume of soil in a potted plant requires a different approach than a garden bed. For potted plants, physical methods are often the safest option to avoid root damage or chemical contamination. A highly effective technique is submerging the entire pot in water for 15 to 20 minutes, forcing the ants to flee the soil and collapsing their tunnels.
If using baits, place them in enclosed stations outside the pot rather than directly in the soil to prevent contaminating the growing medium. Any drench or soil treatment must be done gently to avoid washing away the soil or causing phytotoxicity to the roots, which are vulnerable in a small container. The limited drainage of potting mix means concentrated products can easily become trapped around the root ball.
In contrast, garden beds and lawns benefit from broader, more scalable treatment options. Granular baits and contact insecticides are typically broadcast over a wider area or applied directly to individual mounds. Granular products require light watering after application to dissolve the active ingredient and carry it down into the soil. A perimeter treatment around the garden or home foundation can establish a long-lasting barrier against new ant invasions.