Today 
Tomorrow
Of the black, red and yellow ants that are commonly seen in the garden, only the red ones (from the Myrmica species) sting. Other than that, ants are more of a nuisance than a pest. They feed mostly on insects, including other ants, and honeydew, the sweet sticky substance that aphids excrete. Ants are known to defend aphids against predators in return for a harvest of honeydew.
Solution
Organic
Ants are persistent and it's almost impossible to eliminate them in the garden. You can flush them out from containers by giving the compost a thorough drenching with water. Repeat as necessary, although take care not to drown your plants!
Keep ants off the benches in a greenhouse by wrapping a grease band around each bench leg, or standing the legs on a block of wood in a dish of water. Use a stiff brush to remove ant hills in the lawn.
Chemical
There are many ant killer products on the market, but they are mostly more effective at killing ants that stray indoors, than complete nests in the garden.
