Because plants are frequently watered and provide sustenance, ants will often build nests among the roots. But ants and plants don't always make good neighbors. Some ants can strip the bottoms of plant stalks so effectively that the plants cannot survive. If you have an ant problem in your garden, it can be difficult to remove the colonies without harming the plant itself. Homemade remedies such as pouring boiling water on the colonies will not work without damaging plants, but there are other effective solutions.
Apply an organic ant bait containing spinosad around your plant in the early evening hours. Organic ant baits are typically made of corn grit soaked with oil. The forager ants take the bait back to their colony and feed their queen, which eventually kills the colony. Do not administer ant baits early in the day when they can become saturated with dew. This will cause the oil to become rancid.
Brew a pot of mint tea. Mix the tea with insecticidal soap according the package directions. Pour the tea into a spray bottle. Spray ants whenever you see them. These spot killers will kill worker ants that emerge from the ant hill but not the ant colony.
Measure the size of your ant mound with a measuring tape. Mix a liquid formula containing an insecticide such as dursban, diazinon or sevin and water in a bucket. Use the amount of insecticide recommended on the brand's packaging. Typical mixes include one to two tbsp. of insecticide per gallon of water.
Using 1 gallon per every 6 inches of mound diameter, pour the liquid formula over the mound and the ground around it in a 3-foot radius to cut off any side passage routes ants can use to escape. Drench treatments are most effective during sunny weather when the temperature is below 90 degrees.
Mix together 1 cup water, 1/2 cup sugar and 1 1/2 teaspoons of boric acid. Saturate cotton balls with the mixture and place them in the bottom of plastic water bottles. Leave the lids off of the bottles and lay them on their side around the plant where ants can get to them. The ants will take the bait back to the colony and slowly kill it.
Scatter dry grits around the entrance of the colony. Ant will eat the grits, which expand when eaten and kill the ants.