How to grow potatoes

Seed potatoes: what to buy and how to prep

Always start with certified disease-free seed potatoes from a reputable seed supplier or garden center, never grocery store potatoes (which may be treated to prevent sprouting and can carry disease). Certified seed stock is inspected and free from common viral and bacterial pathogens.

Planting

Set seed pieces cut side down using the planting depth and bed layout on the potato plant profile. Keep the rows accessible from both sides because repeated hilling and regular beetle scouting require room to work.

In a raised bed or container, leave enough empty depth above the seed pieces for repeated hilling and enough access to harvest without cutting tubers.

Cover seed pieces with soil, firm gently, and water in. Shoots should emerge in 2 to 3 weeks depending on soil temperature.

Hilling: the non-negotiable step

Hilling is the practice of mounding soil up along the stems as plants grow. It matters for two reasons: it keeps developing tubers covered so they do not turn green (green potato flesh contains solanine and is mildly toxic), and it gives tubers more loose soil to expand into, which often improves yield.

Watering and feeding

Potatoes need consistent moisture while tubers form. Dry soil followed by saturation can produce knobby, misshapen, or cracked tubers. A soaker hose delivering slow moisture at the root zone is ideal. Use the weekly baseline on the potato profile, then adjust for rainfall and soil texture.

Back off water significantly once the vines begin to yellow and die back. Wet soil at harvest leads to disease and poor storage. Stop all water about 10 to 14 days before you plan to dig.

For feeding, potatoes respond well to a balanced organic fertilizer worked into the soil at planting. Once plants are a few inches tall, a side-dress of a vegetable fertilizer supports the long growing season without pushing excessive leaf growth at the expense of tubers.

Common problems to watch

Colorado potato beetles are the most consistent pest: large yellow-and-black-striped beetles and their reddish larvae devour foliage fast. Scout every few days and pick off egg masses (orange clusters on leaf undersides) before larvae hatch. Flea beetles riddle new foliage with small holes and are most damaging on young plants. Wireworms damage tubers underground and are hard to manage once present; rotate away from grass-preceded beds.

On disease: early blight shows up as dark lesions with concentric rings on lower leaves; late blight causes water-soaked lesions that spread rapidly in cool, wet weather. Both are managed with rotation, good airflow, and prompt removal of infected material. Potato scab roughens the skin and is reduced by following the profile's soil target and keeping moisture even during tuber set.

Harvesting and curing

New potatoes are small, thin-skinned tubers eaten soon after digging. Once plants flower, carefully open the side of one hill and check a few tubers without uprooting the main plant.

Full-size storage potatoes are ready when the tops have fully yellowed and died back. Wait 10 to 14 days after dieback before digging; this waiting period thickens the skins for better storage.

Dig carefully with a garden fork, inserting it at the outer edge of the hill to avoid spearing tubers. Lift, brush off loose soil, and spread in a single layer in a cool, dry, shaded spot (not the sun) for 1 to 2 weeks to cure. Cured potatoes store for months in a cool (38 to 40 degrees F), dark, humid space.

Potatoes in the rotation

Potatoes are heavy brassica-rotation partners in the sense that they share important rotation rules: never follow themselves or other nightshades (tomatoes, peppers) in the same bed for at least 3 years. Both early and late blight, plus soil-borne pathogens, build up quickly without rotation. See the crop rotation guide for a practical rotation schedule.