The potato is a tuber, or special underground stem that stores energy for the plant. It develops below the soil, straw or mulch covering. Each tuber is capable of sprouting a new plant from special structures called eyes. Since several eyes exist on each potato, they are often cut into pieces to increase the number of plants from each seed potato.
Digging the Soil
Regardless of which method you plan to use to grow your potatoes, you need to dig the soil to a depth of 8 to 12 inches. Potatoes grow best in loose, well-drained soils. Hard packed soils and clays inhibit the formation of potato tubers and produce misshaped potatoes. The soil needs to be loose enough that the tubers can easily expand.
Seed potato pieces need to be planted approximately 9 to 12 inches apart in furrows 2 to 3 inches deep. Cover the pieces with soil and keep the soil moist.
Straw potatoes are grown differently. Plant the potatoes in a trench dug 4 inches deep and 12 inches wide. Place the seed potatoes directly onto the surface of the prepared soil and push them into the soil about 1/2 inch. Fill the trench with 4 inches of straw or loose mulch. The potato plants emerge and grow above the straw, while the tubers form on the surface of the soil.
Potatoes grow well in large containers when supplied with loose, well-drained soil. The container must have holes for drainage to prevent the potatoes from rotting. Plant one or two seed pieces in each container, approximately 2 to 3 inches deep.
Growing Vertical Potatoes
Another method of growing potatoes in a small space calls for planting the potatoes on the surface of the soil and covering them with 2 to 3 inches of soil. As the potatoes grow, continue to cover the vines with more soil, leaving only the growing tip with a few leaves above ground. Tubers will grow on the covered stems. Use late season potatoes for this method
Covering Growing Tubers
As the potatoes grow, some may push through the surface of the soil or straw. Left exposed, they will turn green. Prevent this by covering exposed potatoes with more soil or straw to keep them out of sunlight.