How to Grow Potatoes Indoors

Why grow potatoes indoors

Growing indoors means you aren't tied to the outdoor season, there's no frost or summer heat to plan around, and there are fewer pests. A basement, a garage that stays above freezing, or a spare room with a grow shelf can all work. The trade-offs are the cost of running a light for months, and the space a full-size potato plant needs.

Light

Potatoes need strong light for the leaves to feed the tubers, and a sunny window is rarely enough. A full-spectrum LED grow light is the usual choice, because it gives strong light without much heat. Hang it at the height the maker recommends and raise it as the plant grows. Stems that stretch long and thin, with wide gaps between the leaves, are a sign the light is too far away or too weak.

Put the light on an outlet timer so the day length stays the same every day. Very long days can delay tuber formation in some potato varieties, so don't run the light around the clock.

Temperature

Potatoes like cool roots. Tubers form best at roughly 60 to 70°F (15 to 21°C), and tuber growth slows when the root zone stays above about 80°F (27°C). That makes a cool basement one of the best places for an indoor crop. Keep the container away from heaters and from the warm air near the top of a room, and in a garage, make sure the plant never gets frosted in winter.

Space

A potato plant grows much taller and wider than a lettuce, and it can flop over the edge of the container late in the season. Leave room above the plant for the light to move up, and room around it for air to move. One plant per container still applies indoors. Put the container on a tray to catch any spills when you top up.

Choosing a variety

Choose an early variety with a compact plant, such as Yukon Gold or Red Norland. Early varieties finish sooner, which means fewer months of running a light, and smaller plants are easier to fit under it. Late varieties such as most russets are a hard crop indoors. See potato varieties for Kratky growing for more on choosing.

Airflow and pests

Still indoor air keeps leaves damp and invites disease. A small fan, set to move the leaves gently, helps. Indoors, the pests to watch for are aphids on the undersides of the leaves and fungus gnats, which breed in damp coco coir. Check the leaves when you top up, and keep the surface of the medium from staying wet.

Running costs

The light is the main running cost of an indoor crop. To estimate it, multiply the light's wattage by the hours it runs each day and the days the crop takes, then by your electricity rate. An early variety that finishes in about 70 to 90 days costs far less to light than a late one. LED grow lights use much less power than older lamp types for the same light.

Buying seed potatoes for an indoor crop

Indoors you can plant at any time of year, but seed potatoes are only sold in season, from late winter into spring. Buy them then and keep them somewhere cool, dark and dry until you plant. See where to buy seed potatoes. For the full setup, follow how to grow potatoes without soil, and see the list of Kratky potato supplies for the light and timer.