How to Plant Seed Potatoes

seed potatoes

The Spruce / Sandhya Moraes 

Potatoes are one of the easiest vegetables to grow. All you need is a mature potato from the variety that you want. It grows vegetatively, meaning you transplant a whole or part of the actual potato. This is a seed potato. This term can be a bit confusing since they are not seeds at all. If you have ever wondered why you do not see potato seeds packets for sale, it's not that potatoes don't set seeds; rather, potatoes grow more expediently by vegetative propagation. (Potato seeds are available, but growing from seed potatoes is actually easier for many home gardeners.)

When to Plant Seed Potatoes

Potatoes do best in full sun. They can be planted in the early spring 2 to 4 weeks prior to expected last frost date. Seed potatoes planted in soil that is too cold or soggy may rot. Generally, potatoes will not grow until the soil temperature has reached 45 degrees Fahrenheit. You can plant a second crop as late as June 15 and harvest the potatoes as late as possible. Potato plants will tolerate a light frost, but protect plants from freezes with row covers, or harvest before a freeze arrives.

Working With Potatoes

Potatoes are aggressively rooting plants and will produce the best crop when planted in a light, loose, well-drained soil. Potatoes prefer a slightly acid soil with a pH of 5.0 to 7.0. However, potatoes are prolific growers and often adaptable to poor soil and climate conditions. Make sure to rotate where you plant potatoes in the garden, as soil-borne diseases can linger in the ground and affect future crops.

When selecting seed potatoes, do not try growing potatoes from potatoes you buy at the grocery store. Grocery produce is often treated with a growth inhibitor, which keeps potatoes fresher longer but also prevents sprouting or stunts growth.

Organically grown potatoes may be free of growth inhibitors, but they are prone to any diseases carried over from their growth period (like ring rot or fusarium wilt). You need disease-free, certified seed potatoes. Discard any seed potatoes that have a soft spot, cracks, bruises, or signs of rotting.

Before you plant your seed potatoes, you may also decide to chit or pre-sprout your potatoes. If you decide to encourage stem growth on your potatoes, this process will add 2 to 4 weeks to the process. However, many gardeners find that chitting potatoes produces a quicker, slightly larger harvest.

Project Metrics

  • Working Time: 30 minutes
  • Total Time: 4 weeks (depending on if you chit your potatoes)
  • Material Cost: Approximately $1 per pound of seed potatoes

What You'll Need

Equipment/Tools

  • Knife

Materials

  • Seed potatoes
  • Powdered sulfur (optional)
  • Bag (optional)
  • Egg carton, box, tray, or screen (optional)
materials for planting seed potatoes
The Spruce / Sandhya Moraes 

Instructions

  1. Chit Your Potatoes (Optional)

    Although potatoes will sprout in the dark, you will get long, pale shoots that easily break. Instead, place them in a cool spot with bright light for 2 to 4 weeks. This way, the sprouts will grow stocky, sturdy, and dark green. This process is also called greening. You can place your seed potatoes upright in an egg carton or box, on a tray, or screen with the majority of eyes, or buds, facing up. Do not pile them. You can start 1 month before your outdoor planting date.

    seed potatoes in a cardboard planter
    The Spruce / Sandhya Moraes 
  2. Cut the Potatoes (Optional)

    You do not need to plant a whole, intact potato. Seed potatoes can be cut into pieces. Each piece should have at least one eye each. An "eye" is the bud that sprouts into a new plant. Use a sharp, clean knife to cut the seed potatoes into 2-inch squares. If you are going to cut them, do it about two days before you plan to plant. This allows the pieces to callus or seal which prevents rotting while the pieces sprout and take root. If your seed potato is smaller than a ping pong ball, though, plant it whole.

    cutting seed potatoes in half
    The Spruce / Sandhya Moraes 
  3. Plant the Sprouted Potatoes

    Plant your potatoes as soon as the sprouts are 1/2 inch to 1 inch long. Handle the seed potatoes carefully, so the sprouts do not break off or become damaged. Plant with the sprouts facing up and cover lightly with soil. If you've cut the seed potatoes, make sure the cut side is facing down.

    seed potatoes being planted
    The Spruce / Sandhya Moraes  
  4. Plant in Rows

    Potatoes grow best planted in rows spaced 3 feet apart. Dig a trench 6 to 8 inches deep. Place cut side down, with eyes facing up. Space the seed potatoes 12 to 15 inches apart. Fill the trench with 4 inches of soil. As the plants grow, add more soil to mound around the plants.

    seed potatoes planted in rows
    The Spruce / Sandhya Moraes
  5. Water Well

    Keep potatoes well-watered throughout summer, especially when flowering. During flowering, the plants create tubers. Potatoes need 1 to 2 inches of water per week to produce well.

  6. When to Harvest

    When foliage turns yellow, discontinue watering to begin the curing process for harvesting. You can harvest baby, or "new" potatoes 2 to 3 weeks after flowering ceases. Dig around the plants carefully to remove new potatoes for fresh eating, and leave smaller potatoes to continue to grow.

    For potatoes you plan to store, harvest the crop 2 to 3 weeks after the foliage dies back. Carefully loosen the potatoes with a garden fork and remove them from the bed. If the weather is dry, leave the potatoes in the garden, unwashed, for 2 to 3 days to cure, or move them to a protected area, like a garage or shed, to cure.

    harvesting seed potatoes
    The Spruce / Sandhya Moraes 

Planting Seed Potato Tips

  • You do not have to chit the potatoes to get a good crop. However, you might want to chit your potatoes if you notice them beginning to sprout or if you want an earlier harvest date. If you plan to eventually cut them before planting them, chit before cutting them.
  • When planting whole seed potatoes or pieces of potatoes, in general, more eyes per piece equals more potatoes. Smaller potatoes with one or two eyes per piece mean fewer potatoes, but they will be larger.
  • To further protect your seed potatoes, you can dust them with powdered sulfur right after cutting them. Place the potatoes in a bag, add the sulfur and shake. Then lay the pieces out and let them dry for three to four days.
  • If you have to postpone planting because of weather or some other reason, move them to a cooler spot to slow down their growth. Don't wait too long; your seed potatoes may start to dehydrate and shrivel.
  • On average, one pound of seed potatoes should yield about 10 pounds of potatoes. One pound of seed potatoes should plant a 5 to 8-foot row, depending on the variety.
  • Potatoes also perform well in grow bags, which is a good alternative if you have issues with voles in the garden. Fill a grow bag halfway with potting mix, plant the seed potatoes, and continue to add more soil to the bag as the potatoes grow. To harvest, spread out a tarp or sheet, and dump the bag. Kids especially enjoy sorting through the bag to find potatoes!