How to Grow Potatoes

Step 1: Choose Seed Potatoes

Start with organic, certified disease-free seed potatoes obtained from a catalog or farm store. (Grocery store potatoes that have been treated with a sprout-retardant are not suitable for planting.) If you buy from a farm store, as I do, try to select tubers which have already sprouted. Otherwise, pre-sprout them by simply laying them out on your kitchen counter. Pre-sprouted potatoes can be harvested a few weeks earlier than their non-sprouted kin.

Step 2: Separate the Eyes

Only small, golf ball-sized potatoes should be planted whole.

Cut large tubers into pieces. I cut mine so that each segment has two or three "eyes" (the little bumps from which sprouts emerge, as shown in the photo). The reason for cutting the potatoes is because the many eyes on a large potato will create a crowded, multi-stemmed plant, with each stem competing for food and moisture, and in the end, bearing only small potatoes.

Step 3: Cure the Cut Pieces

Next, "cure" the cut pieces. Either set them out in the sun, or place them on a table or counter in a warm (about 70°F), moderately lit room for three to five days. This step permits the cuts to become calloused. Calloused seed potatoes will help prevent rot.

Step 4: How & When to Plant Potatoes

Plant seed potato segments cut-side down (eyes up) in a 6-inch-deep hole or trench. Space each segment 12-inches apart on all sides.

Between each segment, sprinkle 2 tablespoons of a low-nitrogen, high-phosphorous fertilizer. Then cover both potatoes and fertilizer with 2-inches of soil, and water the soil well.

When do you plant potatoes?

This will vary depending on where you live. Gardeners in warm climates often plant around Valentine’s Day, while those in cooler areas may get them into the ground near Easter, or early spring. A good rule of thumb is to aim for 3-4 weeks prior to your last frost date.

Step 5: Hill Around the Stems

Because new potatoes form on lateral stems, or "stolons" above the seed potato, it’s necessary to "hill" the vines. When the green sprouts achieve 8 inches in height, bury all but their top 4 inches with soil, chopped straw, or shredded leaves. Hill again when potato plants grow another 8 inches. The more you hill, the more prolific your harvest is likely to be. I usually hill mine to a height of 18 inches. Stop hilling when the vines flower.

Potato tubers, like vampires, need to live in darkness. In fact, they will turn green if exposed to light. And a green potato can cause sickness if consumed. Therefore it is absolutely essential to keep the tubers covered with soil or mulch.

Step 6: How & When to Harvest Potatoes

Two weeks after the vines have flowered, you can, if you wish, reach into the soil or mulch and retrieve a few baby potatoes. Otherwise, wait until the vines die back. Dead vines signal that the tubers have reached maturity. Now reach into the soil with your hands and pull the tubers up.

How long do potatoes take to grow? Small new potatoes can be ready as early as ten weeks. However, full sized potatoes take about 80-100 days to reach maturity.

Step 7: Store Your Potatoes

Since my potatoes are grown for storage, I leave them in the ground until cool weather arrives. Why? Because potatoes will only store well if they are placed somewhere cold, but not freezing. The closet in my mudroom doesn’t cool off until the outside temperatures plunges to 45° at night. So harvest time for me is usually a sunny day in late October.

After digging the tubers, I let them sit on top of the raised beds for a few hours to dry, as illustrated. This brief drying-period toughens their skin, and prepares them for storage. Then I gently brush off any loose soil from the tubers, and place them in double thicknesses of paper bags.