Potatoes: Potatoes can be a rewarding crop if you have room in your garden. Each plant takes up four square feet of garden space with vines growing about two feet high; however, for each pound of seed potatoes planted, the average yield is 10 pounds of potatoes. Planting dates Potatoes can be planted from March to June.
In Yellowstone County, the first crop can often be planted on Good Friday, or as soon as the soil can be worked. If you plan to store potatoes through the winter, plant a second crop as late as June 15. Choosing the site Choose a location that is sunny, with light, well-drained soil. Potatoes planted in poorly drained soil often produce deformed, knobby tubers.
Preparing the “Seeds”
A potato “seed” is just a cut piece of potato, usually about the size of a small egg and having at least two “eyes” from which sprout will emerge. the cut pieces can be left to dry overnight and planted the next day or they can be left in a light place indoors until they form 1/2 inch long green sprouts and then planted outdoors. Several varieties do well in our area. You may choose either early or late potatoes, depending on whether you plan to store them. Color choices include red, white, gold and even blue!
Planting: There are two ways of planting potatoes-either covered by soil or mulched over with straw. Either way, you can speed up the growth by covering the rows with clear plastic to warm the soil in March and April.
1. Soil Method-Place seed potato pieces cut side down in a 4 inch deep trench. Space the pieces 15 inches apart. Rows should be 2 1/2 to 3 feet from each other. Cover chunks with 2 inches of soil. As spouts emerge, add another 2 inches of soil to the furrow. As potato vines grow, continue mounding soil up over each row until mounds are approximately 4 inches high and 18 inches wide.
2. Straw Method-Place seed pieces cut side down directly on top of the ground 15 inches apart in rows 2 1/2 to 3 feet from each other. along each side of the row, place four inch-thick “flakes” of straw (from a bale) side-by-side on top of the cut seed pieces. Allow the vines to grow up through the center row of straw flakes. The foliage should never be completely covered after it has emerged from beneath the straw.
Fertilizer: At planting time, fertilize in bands along both sides of the row with a fertilizer formulated for our soils, such as Jirdon® Vegetable Fertilizer (12-16-14). Keep the band of fertilizer at least 2 inches from the seed potatoes.
Watering: Keep potato vines well watered through the summer, especially during periods of drought. Try to water only in the mornings in order to allow foliage to dry before evening. Wet foliage can make a plant more susceptible to several potato blight diseases. Discontinue watering after foliage turns yellow.
Cultivation: Since new potatoes form between the cut piece and the soil surface, it is necessary to avoid hoeing weeds too close to the row. Instead, hand weed on top of the rows and scrape soil from between the rows up around the stems of the vines. Another method is to mound straw around the base of each plant. Either way, the goal is to cool the soil, maintain a more constant moisture level, and protect the developing tubers from the sun, which would turn them green and inedible.
Harvesting: Potatoes can be harvested during the season by gently loosening the soil and removing the largest tubers, leaving the smaller ones to continue growing. Usually, early potatoes can be harvested when you see the plants begin to flower. If you used the straw method of planting, simply reach beneath the straw layer. If you want late potatoes for storage, wait 2 weeks after the foliage begins to die back. Remove the potatoes with a spade, being careful not to bruise the skins. Allow the potatoes to dry, unwashed, for two-three days. Store unblemished potatoes only, in a well-ventilated, dark, cool (about 40 degrees) location. If these conditions are met, potatoes should keep well for three-six months.