Gardeners can control snails effectively by removing any hiding places, applying physical barriers, using traps, handpicking snails, and using natural predators or remedies such as nematodes, diatomaceous earth, or copper tapes. They can also discourage snails by watering in the morning, using drought-tolerant plants, and practicing good garden hygiene. Additionally, gardeners should avoid using chemical pesticides that can harm other beneficial insects and the environment.