Potatoes can be started in your garden from small seed pieces cut from a potato. Each seed piece must contain an "eye" from which the plant will develop. One important factor to consider when planting your seed pieces is the spacing between each plant. In a study published in Volume 33, Issue 3 of Potato Research, it was found that the spacing between plants affects root growth, ability for stems to branch and the size of tubers produced. You can control these factors more by giving your plants plenty of space.
Select an area with well-drained soil to plant your potato seed pieces. Loosen the soil in your garden to a depth of 6 inches with a shovel, and add compost to the soil evenly to improve drainage.
Dig a 3-inch deep trench in your garden area. Make rows of trenches that are each spaced 24 inches apart. A spacing of 24 inches allows room for your potato plants to grow, while also providing shade when foliage develops so that soil temperatures don't get too hot for tubers to develop.
Lay the seed pieces so that they are spaced a foot apart within each trench. Spread 2 inches of soil over each trench once all the seed pieces have been sown.
Dig a 3 1/2-inch trench that is spaced about 6 inches to each side of your plants when they are about 6 inches tall. Add 10-20-20 fertilizer to the trench in a 2-inch band, and cover it with soil. Use approximately 2 lbs. of fertilizer for every 100 feet of row.
Mound the soil around the base of each plant once they are 6 inches tall. Add a 1-inch layer of mulch around the plants to keep the soil cool. Continue to mound dirt around the plants once they are 1 1/2 feet tall so that there is a 4-inch mound of dirt around each.