How to Grow Potatoes
Wondering how to grow potatoes? The taste and the texture of homegrown potatoes are far superior to those of store-bought spuds, especially the early varieties. Here’s how to plant, grow, and harvest potatoes in your garden.
When to Grow Potatoes
Potatoes need a cool climate, and also need to be watched to prevent sunburn. In warmer climate zones, potatoes can be grown as a winter crop.
Potatoes prefer cool weather, well-drained, light, deep, loose soil (45° to 55°F), high in organic matter. Unlike most vegetables, potatoes perform best in acid soil with pH 4.8 – 5.5. (Scab is less of a problem at low pH. If pH is more than 6.0, use scab-resistant varieties.)
Folklore offers many “best days” for planting potatoes:
- Old-timers in New England planted their potato crops when they saw dandelions blooming in the open fields.
- The Pennsylvania Dutch considered St. Gertrude’s Day (March 17, aka St. Patrick’s Day) to be their official potato-planting day.
- Many Christians believed that Good Friday is the best day to plant potatoes because the devil holds no power over them at this time.
- Yet another tradition suggested planting before the vernal equinox (March 19 or 20).
All of these “best days” suggest an early spring planting!
How to Plant Potatoes
- Plant 0 to 2 weeks after last spring frost. (See local frost dates.) You may start planting earlier, as soon as soil can be worked, but be aware that some crops may be ruined by a frost.
- Spread and mix in rotted manure or organic compost in the bottom of the trench before planting. (Learn more about soil amendments and preparing soil for planting.)
- The best starters are seed potatoes—whole tubers from which “eyes” protrude. (Do not confuse seed potatoes with potato seeds or grocery produce.) Use a clean, sharp paring knife to cut large tubers into pieces that are roughly 1 to 4 ounces each, making sure that there is at least one eye on each piece. (Tubers that are smaller than a hen’s egg should be planted whole.)
- If you are cutting up potato pieces for planting, do so 1 to 2 days ahead of time. This will give them the chance to “heal” and form a protective layer, both for moisture retention and rot resistance.
- With a hoe or round-point shovel, dig a trench about 6 inches wide and 8 inches deep, tapering the bottom to about 3 inches wide. Put a seed potato piece, cut side down, every 14 inches and cover with 3 to 4 inches of soil.
- In 12 to 16 days, when sprouts appear, use a hoe to gently fill in the trench with another 3 to 4 inches of soil, leaving a few inches of the plants exposed. Repeat in several weeks, leaving the soil mounded up 4 to 5 inches above ground level (this is called “hilling”).
Companion Plants for Potatoes
Potatoes are deep-rooting vegetables, which logically suggests that the best companions will be those with above-ground growth habits that do not infer with the root systems of the potatoes. Lettuce, spinach, scallions, and radishes are shallow-rooted veggies that are a good choice for occupying the spaces between potato plants. Because potatoes are harvested late in the season, the best choices for planting right around the potato hills will be early season vegetables that will be harvested well before you need to stomp around the garden to keep up the potatoes.
There are several plants that are said to enhance the flavor of the potato tubers, including chamomile, basil, yarrow, parsley, and tyme (they also welcome in beneficial insects). Beans, cabbage, and corn all will help potatoes grow better and hence improve the flavor of the tubers.
Horseradish is said to make potatoes resistant to disease, and petunias and alyssum will also attract beneficial insects that feast on insects destructive to potatoes. Colorado potato beetles are a particular problem for potatoes, and among the plants that repel this damaging pest are tansy, coriander, and catnip.
How to Grow Potatoes
- Do not allow sunlight to fall on the potatoes, which develop under the surface of the soil, or they will turn green.
- Do the hilling in the morning, when plants are at their tallest. During the heat of the day, plants start drooping.
- If your garden soil is very rocky, put the seed potato pieces directly on the ground and cover them with straw or leaves, hilling the material up as the potatoes grow.
- Maintain even moisture, especially from the time when sprouts appear until several weeks after they blossom. If you water too much right after planting and not enough as the potatoes begin to form, they can become misshapen.
- Potatoes need consistent moisture, so water regularly when tubers start to form.
- Hilling should be done before the potato plants bloom, when the plant is about 6 inches tall. Hoe the dirt up around the base of the plant in order to cover the root as well as to support the plant. Bury them in loose soil.
- Hilling keeps the potatoes from getting sunburned, which can cause them to turn green and produce a chemical called solanine. Solanine gives off a bitter taste and is toxic, so do not eat green potatoes.
- You will need to hill potatoes every couple of weeks to protect your crop.
How to Harvest Potatoes
- Harvest baby potatoes 2 to 3 weeks after the plants stop flowering. For mature potatoes, wait 2 to 3 weeks after the foliage has died.
- Dig potatoes on a dry day. Dig up gently, being careful not to puncture the tubers. Avoid cutting or bruising potato skin. The soil should not be compact, so digging should be easy.
- If the soil is very wet, let the potatoes air-dry as much as possible before putting them in bags or baskets.
- “New potatoes,” which are potatoes that are purposefully harvested early for their smaller size and tender skin, will be ready for harvest after about 10 weeks.
- New potatoes should not be cured and should be eaten within a few days of harvest, as they will not keep for much longer.
- For the biggest and best potatoes, harvest only after the plant’s foliage has died back. Cut browning foliage to the ground and wait 10–14 days before harvesting to allow the potatoes to develop a thick enough skin. Don’t wait too long, though, or the potatoes may rot.
- Allow freshly dug potatoes to sit in a dry, cool place (45°–60°F) for up to two weeks. This allows their skins to “cure,” which will help them keep for longer.
- After curing, make sure you brush off any soil clinging to the potatoes, then store them in a cool, dry, dark place. The ideal temperature for storage is 35°–40°F.
- Do not store potatoes with apples; their ethylene gas will cause potatoes to spoil.
- Whether you dig your own potatoes or buy them at a store, don’t wash them until right before you use them. Washing potatoes shortens their storage life.