Generally, potatoes have a shallow root system. Most moisture is taken up from the top foot of soil. Be particularly careful to avoid overwatering during the first weeks after planting. After plants have emerged, irrigate every three to five days, thoroughly wetting the soil to a depth of about 2 feet. Do not subject potato plants to water stress, as this will result in lower yield and misshapen tubers.
Water stress is indicated by wilting and a dark gray-green hue to the foliage.
Leaflets may roll slightly. Maximum water use occurs during vine growth and early tuber development. To prevent the maturing tubers from being predisposed to rot organisms, reduce watering when vine death begins. In the home Garden, weeds are most easily controlled by hoeing, pulling and light cultivation before the plants reach 8 to 10 inches tall. Avoid cultivation after this stage, as root damage may occur which will reduce yield.