Got a particular plant that needs regular watering? These petite glass vessels slowly release water into the soil, and look great doing it—just fill with water, insert the cork, and turn them over in the earth. Adjust the cork and the soil contact as needed to obtain the right flow of water; typically they will drip for 3 to 4 days. Each holds about 7 ounces of water and they measure about 4 inches long—choose between the single crystalline vessel or the two-stone set.