Pick a container that holds 10 to 15 gallons, has drainage holes, and doesn't let light through. Fabric grow bags, food-safe tubs, and bins all work. Tubers that see light turn green. Fill it with a mix of potting soil and compost, about half and half. Skip , which compacts in containers and can carry disease and weed seeds. Plan on about 5 gallons of mix per plant, so a 10- to 15-gallon container fits 2 or 3 seed pieces.
Start with certified seed potatoes rather than grocery-store potatoes, which may carry disease or be treated to slow sprouting. Cut large ones into pieces with at least one eye each, and let the cut sides dry for a day or two. Plant about 2 weeks before your last spring frost, as you would in the ground, and move the container somewhere sheltered if a hard frost threatens after the shoots are up. Put 4 to 8 inches of mix in the bottom, set the pieces on it with the eyes up, and cover them with 3 to 6 inches more.
As the shoots grow, keep burying the stems. When plants are a few inches tall, add mix until only the top few inches of leaves show, and repeat each time they grow until the mix nears the rim. New tubers form along that buried stem, and the extra cover keeps them dark. Mid- and late-season varieties keep setting tubers longer and tend to make better use of the extra depth than early types.
Watering is where container potatoes usually go wrong. Containers dry out much faster than garden beds. Water whenever the top 1 to 2 inches of mix is dry, enough that some drains out the bottom, and keep the mix moist but not soggy. Very tall containers and towers tend to dry at the top while the bottom stays wet, which can rot tubers. A container about 2 to 3 feet tall is easier to manage. Once shoots appear, feed every couple of weeks with a balanced liquid fertilizer.
You can steal a few small new potatoes once the plants flower by reaching gently into the mix. For the main harvest, wait until the tops yellow and die back. Spread a tarp and tip the container out, then sift through the mix by hand. Brush off the soil but don't wash the potatoes, and keep them out of the light. Let them cure somewhere dark for a week or two to toughen the skins before storing them cool and dark. Start the next season with fresh mix.
- Colorado Potato BeetleStriped orange-yellow beetles and soft orange larvae heavily defoliating potato and eggplant.
- Late BlightLarge water-soaked leaf lesions with white fuzzy growth beneath; plants can collapse within days.
- Early BlightDark spots with concentric rings on lower leaves that yellow and drop, working up the plant.
- Southern BlightWhite cottony mycelium and small round sclerotia at the stem base, with rapid plant collapse in warm, moist soil.
- Imported CabbagewormRagged holes in brassica leaves with pale green caterpillars and green frass nearby.
- Why are my potatoes green, and are they safe to eat?Potatoes turn green when light reaches them. The green comes with natural toxins called glycoalkaloids. Peel slightly green potatoes deeply. Throw out ones that are heavily green or taste bitter.
- Why are some of my potatoes hollow inside when I cut them?Hollow heart in potatoes is caused by rapid, uneven growth — usually after a period of drought followed by heavy watering or rain — and is not a disease.
- What does drought stress actually look like, and how do I know when to water versus when something else is wrong?Drought stress progresses from midday wilting to all-day wilting, leaf curl, and eventually aborted fruit and flowers — the key is catching it before the plant has been dry long enough to abort reproductive structures.