Planting Time - When soil is 55-70F. Usually early to mid-May in Montana.
Soil Preparation - Till the soil as deeply as possible to encourage good drainage. Dig a trench approximately 6” deep and place seed pieces in bottom of trench 8-12” apart. If you want larger potatoes use the wider spacing. If you want smaller potatoes or plan to harvest early, 8” is sufficient. Cover seed pieces with 4” of soil. As the potatoes emerge, fill in the rest of the trench.
Hilling - When the stems are 8” high, gently hill with soil brought from both sides. Hill two more times at two week intervals.
Fertilizing - At the second hilling, side-dress with compost, or a small amount of granular fertilizer. Manure can be used, but it often promotes the development of a disease called scab.
Watering - Keep potatoes evenly moist but not too wet. Maintaining even moisture as the tubers form will reduce the development of scab.
Weed and Pest Control - Hoeing should take care of emerged weeds. If you suspect a disease problem, contact your County Extension agent.
Harvest - You should be able to harvest “new potatoes” after ~60-70 days. Dig around the edges of the plant with a fork and see if you can rob a few tubers to determine size. You can dig anytime they are large enough for your use. If you plan on taking the potatoes to maturity and storing them over the winter, reduce water in late summer and let the vines die back naturally or cut the vines. After the vines have been dead 2-3 weeks, often after the first frost, dig potatoes and remove as much of the dirt as possible. Store in a cool dark place (not in a refrigerator).