How to Kill Ants on Gardenias

Locate the anthill and slowly pour hot water into the entrance of the ant colony. Ants breathe air, and scalding water will penetrate and soak their home, killing much of the colony on contact. Repeated treatments can soak the ground until the ants find it uninhabitable.

Soak the ground around the ant colony with the garden hose and sprinkler. Doing this over a number of days will make the ground uninhabitable to the colony. The soggy earth will often collapse on the colony, and drive the remaining ants to another location.

Mix equal amounts of borax, sugar and water. Pour the pasty solution around the base of your gardenias and the entrance to the ant colony. Like vacuum cleaners, the forager ants will consume the food and return to the colony to feed the underground members. Sugar attracts the creatures, and borax kills them. This is an approach that can kill the entire colony.

Deposit small amounts of rice and oatmeal on the ground around the ant colony and around the stems of your gardenias. When ants eat the dry grains and then drink water, the grain expands, killing the ants.

Place small amounts of coffee grounds around an anthill, and around the base of your gardenias like a small berm. The chemicals in the coffee grounds are toxic in ants. A small pile of coffee grounds will provide the ants with a fatal meal they can't refuse.