image by Hans Thoursie/sxc.hu
Potatoes are cool-season vegetables that are easy to grow in home gardens. Potatoes are not actually roots--they are tubers, or specialized underground storage stems. More than 100 varieties of potatoes exist. Along with wheat, rice and corn, potatoes are an important staple for humans.
Decide what variety of potatoes you are going to grow in the garden. Purchase certified seed potatoes (small potato tubers) because they are inspected for diseases. Supermarket potatoes should not be planted because they are treated with growth inhibitor that prevents them from sprouting.
Plan and prep the garden site. Plant the potatoes as soon as the threat of frost is gone and you can work with the soil. The area should get full sun and have deep, well-drained soil. Use a tiller to loosen the soil 12 to 15 inches deep. Mix in a 2- to 4-inch layer of compost. Dig trenches with a spade or shovel that are 6 inches wide by 6 inches deep and 30 to 36 inches apart. The University of Illinois recommends spacing rows 24 inches apart as the plants shade the soil, preventing high soil temperatures that inhibit tuber development.
Cut the seed potatoes into 1- to 2-inch cubes three to five days before planting. This allows the cut surfaces on the seed potatoes to heal. Make sure there is at least one "eye" (or spot on the potato where they sprout) in each seed piece.
Place the seed potatoes 10 to 15 inches apart. Cover the potatoes with about 4 inches of soil. You can cover the rows with a clear plastic film to promote early growth if the soil temperature is low. You can also grow the potatoes above ground in mulch. Place the seed potato pieces on top of the soil and cover with a layer of straw or pine needles that is 12 to 18 inches. This method makes harvesting easier.
Water the potatoes with 1 inch of water per week (via rain or manually watering). Watering is especially important six to 10 weeks after planting the potatoes, when the potatoes start forming. Add organic mulch to the potato plants after they start emerging. This will help avoid weeds and keep moisture levels down. Build a low ridge of loose soil by hoeing in the direction of the plants. The ridge can become 4 to 6 inches high by summer. This will reduce the number of "sunburned" or green tubers.
Harvest the potatoes about 10 weeks after planting them with a shovel or spading fork. Harvest the plants after the vines die and the tubers develop tough outer skin. An exception to this is harvesting "new potatoes" (the smaller potato variety), which can be dug up before the vines die, usually sometime in July. Other potatoes are usually ready in August or early September.