How to Plant Seed Potatoes

You should always plant with certified seed potatoes from your local farmer's market or garden supply store when possible, as they're guaranteed to be disease free. If you're using your own potatoes saved from last year as seed, select those with smooth, firm unblemished skin. Using supermarket potatoes for seed is chancy at best because they may have been treated not to sprout.

Ideally, potatoes should be planted no earlier than one or two weeks before the last predicted hard frost in your area. They appreciate well-drained, fertile loamy soil and full sun, but may wilt or even die in temperatures above about 90 degrees Fahrenheit.

Seed potatoes

Sharp knife

Shovel or large spade

Store your seed potatoes in the refrigerator or another cool, dry, and dark spot until about a week before planting time. Keep them well away from onions; exposure to onions may cause the potatoes to soften faster. One week before planting, place the potatoes in a bright, sunny window.

Cut the seed potatoes into pieces at least a day before planting time. Each piece should be no smaller than two inches square, and each piece must have at least one eye. Lay the cut potatoes out on a tray or on sheets of paper towel to dry overnight.

Use the shovel or a large spade to dig a trench in the garden where you plan to plant your potatoes. The trench should be between 3 to 4 inches wide and 6 to 8 inches deep. Place your seed potatoes in the trench, cut side down, eyes facing up, each piece of seed potato between 4 and 15 inches apart. How far apart you space them determines the size of the potatoes; planting close together yields fast harvests of baby potatoes, while plants spaced further apart will take longer to mature, but will produce much larger potatoes.

Cover the potatoes in the trench with 3 or 4 inches of soil. Once the potato sprouts emerge over this layer of soil, fill in the rest of the trench with the other 3 to 4 inches of soil.

Water your potatoes regularly--the soil should be moist but not wet.

You can also plant potatoes in garbage cans--make sure to drill a couple of holes in the bottom and low sides of the can to provide adequate drainage--or in stacks of old tires. Just plant the potatoes in the bottom of the garbage can and cover them with a couple inches of soil. When the sprouts poke through the soil, add a few more inches of soil. Once the sprouts poke through that layer, add more soil, and continue this until the potatoes reach near the top of the garbage can. Increasing the length of the stems in contact with the soil means more potatoes.

Planting in a stack of tires works basically the same, except that you start with potatoes planted in a single tire, then add more tires on as necessary to support more soil.

Your potatoes will appreciate being fertilized with compost. Put the compost in the trench below the seed potatoes, mix about an inch of regular soil in with this, then plant the seed potatoes on top of the fertilizing organic matter.

Once you've grown potatoes in a particular plot, you should give that plot a two-year break before planting potatoes, or related plants, again. This helps prevent the spread of disease.