Potatoes aren't started by seed, they're started from Seed potatoes or "slips". Slips are shoots that are grown from a mature tuber. Seed potatoes from a catalog either online or print are generally the best way to go, as supermarket potatoes are treated with a chemical growth inhibitor to prevent sprouting.
The soil should be evenly moist, but not wet or soggy. If the soil is waterlogged when you dig, your seed potatoes will probably rot before they grow. Potatoes are a hardy crop and can tolerate climatic aberrations, light frost etc..,but you should provide some frost-protection for the young plants. A temporary ground cover (ventilated), or mulch.
Full Maturity at 95-125 days.
Early [New or Baby] Potatoes at 75-80 days
Color - Skin: Golden Yellow Flesh: Light Yellow
Size: Grade C - See Potato Sizes for explanation
Spacing - 10"-12"
USDA Hardiness Zones 3 - 9
Full Sun - at least 6 hours of sunlight daily.
Height 18-24 Inches
Spread 8 - 10 Inches
Soil ph 4.5 - 6.0 Acceptable. 4.8 - 5.5 is optimal.
Potatoes do well in proximity of Beans, Cucumber, Corn, Kohlrabi, Parsnip, Pumpkin, Rutabaga, Squash family, Sunflower, Turnip, Fennel. Horseradish, planted at the edges of the potato patch will provide protection against some insect scourges, as will Marigolds