Family: Solanaceae
Genus and Species: Solanum tuberosum
Climate
Potatoes are a cool weather crop. If you live in a cool climate, plant potatoes in early spring three weeks before the last frost. If you live in a warm to temperate region, plant your potatoes in late winter. In a truly hot climate, plant potatoes in the fall to grow over the winter.
Soil
Potatoes need fertile, well-drained soil. Potatoes need high amounts of nitrogen, potassium, and phosphorus. Mixing compost into your bed and making sure there is plenty of organic matter will help ensure good soil conditions for your potato crop. Make sure your soil is easy to dig around in, it will make harvesting the potatoes easier. Potatoes need soils at least 45° for sowing and 60°-65° for optimal growing. The ideal pH for potatoes is 5.0 - 5.5 to prevent scab.
Spacing
The common practice is to keep potatoes 6"-12" apart with row spacings of 30"-36".
Direct Seeding
Potatoes are not normally thinned so make sure you plant the potatoes at the proper spacing to begin with to avoid crowding. Plant seed potatoes 6"-12" apart in a shallow holes 3" deep. Use row spacings of 30"-36". Direct seeding is possible for some cultivars but planting seed potatoes is the much more common method of starting potatoes. Seed potatoes are actually nothing more than either a whole or sections of a whole potato. Plant the seed potatoes in early spring, about 3 weeks before the last frost.
An alternate method is to dig a trench 6"-12" deep and place the seed potatoes in the bottom of the trench 12" apart. Cover them with 3" of soil. The trench method allows you to add soil back into the trench as the potato plants continue to grow.
Seed potatoes need some preparation before planting. The practice of greening and pre-sprouting seed potatoes before planting encourages early growth and hastens the development of the potatoes.
Spread the potatoes to be used as seed potatoes in a open-top box, crate or flat. Place the potatoes in the container so that the side with the most 'eyes' (the little dimples) is face up. Do not stack the potatoes. Keep the flats of potatoes warm and in a spot where light levels are medium to intense. The warmth will stimulate development of strong sprouts from the bud eye clusters and the light will keep the sprouts short and strong.
To get more potato plants from one seed potato cut the seed potato into chunks so that there at least three healthy sprouts per chunk. Make sure the potato chunks are at least 1-1/2" across. Allow these to air dry for a day or two before planting.
Seeding For Transplants
Transplanting potatoes is not normally practiced.
Transplanting Into the Garden
Potatoes planted in a hill will dry out quicker so watch the soil moisture carefully. Keep potatoes evenly moist and water deeply during dry spells.
Watering
Potatoes planted in a hill will dry out quicker so watch the soil moisture carefully. Keep potatoes evenly moist and water deeply during dry spells.
Harvesting
Potatoes are mature when the leaves die back. New potatoes are immature potatoes picked several months after planting but before the potato plants reach maturity. New potatoes can often be found when the potato plants blossom.
Mature Potatoes: Once the leaves of the plants have died back, use a garden fork to gently loosen the potatoes from the ground. You will see why it is important to have well drained, light soil- it makes the harvest a lot easier.
New Potatoes: Carefully poke around in the potatoe hill (or under the mulch) by hand to see what's there. New potatoes are often harvested as small as a marble up to the size of a golf ball. If you find something worth taking, pluck it gently from the roots so as not to disturb the rest of the potato plant.
In either case, drier soils are an advantage to harvesting potatoes.
Post-Harvest Handling
Brush the soil from the potatoes but don't wash them. Potatoes need to cure several weeks before storage. Store them in a cool, dry, dark place during this time.
Storage
Potatoes can be stored for 5-10 months in temperatures from 40°-50° and 90% relative humidity for mature potatoes. New potatoes should be stored at 50°-60° and 90% relative humidity.
Mature potatoes are sensitive to ethylene gas so do not store them with fruits and vegetables that produce ethylene gas.
Diseases
Potato Blight, Speckle Leaf, Black Leg, Early Blight, Late Blight, and Ring Rot.
Pests
Colorado Potato Beetles and Pocket Gophers.
Comments
Hill Method: When the potato plants are 1' tall, use a hoe to "hill" the soil around the plant. Hill the potato plants with soil so that just the top few leaves are exposed. This helps prevent the potatoes from turning green and allows the plants to produce more potatoes.
Mulch Method: A good alternative to hilling, especially if your soil is shallow, rocky or compact, is to use mulch to bury the plants. The best mulch to use is loose, seed-free hay or straw. Leaves and dried grass clippings can also be used. Cover the potato plants at least a few times during the growing season.
Cage Method: Grow your potatoes in vertical boxes, cribs, barrels or wire cages. Do not use old tires to grow your potatoes in! Plant strong seed potatoes at the bottom of the container/cage and cover them with 3"-4" of loose soil. As the plants grow, add mellow compost, mulch or soil. Cover the potato plants at least a few times during the growing season. This method is known to produce 2-3 times the amount of potatoes. Watering requirements will be greater if using a wire cage because of the increased soil surface area exposed to air.
References
Bradley, F. M. and Ellis, B. W.(Ed.). (1992), Rodale's All-New Encyclopedia of Organic Gardening: The Indispensable Resource for Every Gardener, Emmaus, Pennsylvania: Rodale Press.
Ronnigers Family Farm, 2003, Ronnigers Potato Farm, Moyie Springs, Idaho, Ronnigers Family Farm.