There are two basic types of potatoes: summer potatoes, also called early or new potatoes, and fall potatoes, also called late or storage potatoes. As the name implies, the summer potatoes will be ready for harvest in July, they are wonderfully sweet, but must be eaten within a week of harvest. The fall potatoes, on the other hand, can keep for up to six months when stored in a cool, dark, and semi-humid place.
The key to successful potato growing is buying healthy seed potatoes. The potatoe plants and tubers can be plagued by a number of diseases, so certified disease-free seed potatoes are a must. Many local nurseries carry several varieties of seed potatoes in spring, usually beginning in early March. Buy your seed potatoes early, because they will often sell out in early April. There is no hurry in planting them, though, because they need close to 60 degrees in the soil to sprout and start growing rapidly. Planting too early in cold, wet soil will subject them to diseases or simply just delay their sprouting. Early April is usually a good time to plant summer potatoes, and mid-May through mid-June for fall potatoes. You can keep the seed potatoes from sprouting too early by storing them in the refrigerator for several weeks. Seeds potatoes weighing about 1/4 lb each are best: smaller ones take longer to develop sturdy plants and may reduce the yields, larger ones are a waste of money. I never cut the seed potatoes, because keeping them intact will guard against soil-borne disease. Summer potatoes will get a quicker start if they are allowed to develop sprouts before planting. Keep the seed potatoes in a shallow box in a light but not too warm place for a couple of weeks until the sprouts are about 1 inch long. Do not allow the sprouts to grow longer, otherwise they will easily break when transporting and planting the seed potatoes.
The potato plot must not have any lime or manure added to it within 6 months of planting to avoid scab disease. Plant the seed potatoes shallowly, so that the bottom of the seed potatoes are just 4 inches below ground level. Cover them with soil and wait for a week or two until they sprout and grow about 4 inches above ground level. Then hill up soil or compost along the stems almost all the way to the top of the plants, covering the stems and lower leaves. This will force the covered portion of the stem to produce more potatoes. When the plants have grown another 4 inches, repeat the hilling one or two more times, until the stems have been covered for a total height of 8-12 inches. Then, add a layer of newspapers on top of the hills around the plants to keep the moisture from evaporating and the soil temperature more even. Finally add a thin layer of straw, grass clippings or leaves on top of the newspapers to keep them in place and make the potato patch look more appealing. Thus hilled, the potato plants can go without watering for most of the growing season, and only when the weather has turned hot and dry by mid-summer should they be watered, but always thoroughly and only once a week. Too frequent watering is the most common mistake, leading to disease and low yields.
Harvest your summer potatoes as you need them, beginning in early July. The fall potatoes should be left in the ground until the temperature stays permanently around 60 degrees or less. The plants will die back in late August or early September. Immediately remove the dead potato tops from the site to prevent any blight spores in them from spreading to the tubers. Then wait for a dry harvest day in October, carefully dig the tubers with a pitch fork, lifting them up from below to avoid spearing them, and place them in well-ventilated crates in the sun for a couple of hours to dry. Do not wash the potatoes, otherwise they will not keep. Store the crates an unheated garage, basement, root cellar or any other dark, semi-moist space where the temperature never drops below freezing. Optimum storage temperature is in the mid-30s. During very cold weather, cover the crates with a thick blanket. The potatoes are living organisms which generate some heat, and covered under a blanket they will not freeze even if the surrounding air temporarily drops below freezing.