Planting: In cold winter regions, plant seed potatoes in spring as soon as the soil can be worked. For a summer crop where the soil temperature does not climb above 85°F (20°C), plant 2-3 weeks before the last frost. For a fall crop, plant in late spring. In mild-winter regions, plant in late winter—4 to 6 weeks before the last frost—for a summer crop. Plant in late summer for a winter-into-spring crop. Potatoes are tolerant of cool soil and late frost. Set seed potatoes 2-4” (5-10 cm) deep and 12-18” (30-45 cm) apart in all directions. Plant in soil rich in compost and rotted manure.
Growing: When plants are 12” (30 cm) tall, draw soil up around them—called “hilling”—so just a few inches (5 cm) of the plant is seen. Hilling will protect potatoes from sunburn and from turning green. Grow potatoes in full sun. Keep the soil just moist. Add a side-dressing of high phosphorus fertilizer to the soil after 1 month of growth.
Harvesting: Potatoes planted in early spring will be ready for harvest in 90-110 days; planted in late spring, 100-120 days; planted in late summer or fall, 110-140 days. Dig early for “new potatoes” when plants begin to bloom and fade; dig for mature, full-size potatoes when the vines yellow and die. To harden the potato skin before harvest, stop watering 2 weeks before harvest; cut away the top foliage 10 days before harvest. Carefully lift potatoes with a garden fork, staring 8-10” (20-25 cm) away from the plant, then work closer t the vine. Brush but do not wash clinging soil from tubers. Store potatoes in a dry, dark, well-ventilated place for up to 6 months.
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