Terrific Tuber Tips
Keep your potatoes from sizzling in the sun by hilling your plants.
As potatoes grow, they send out underground stems, to which the tubers themselves are attached. In some cases, those stems may hover near the soil surface, and when that happens, sunlight will hit the top of the tuber, turning the skin green. In addition to being unsightly, that green portion of the tuber is bitter and, believe it or not, mildly toxic. By hilling the potatoes, or covering the base of the plant with soil or mulch, you can prevent sunlight from reaching the tubers.
Begin hilling when the plants are 8 to 10 inches tall and repeat once or twice during the growing season. If you don't have enough surrounding soil to hill your potatoes, use compost, shredded leaves, hay or straw (fresh or slightly rotted); just be sure to add enough of whatever you use to cover the soil surface to a depth of one to 2 inches. Be careful in the process because you don't want to accidentally damage any shallow stems.