Irish Potato Solanum tuberosum

Solanum tuberosum is the common cultivated potato known for its starchy tubers.  While they are herbaceous perennials by nature, they are grown as annuals for harvesting.  Many cultivars exist in varying textures, sizes, and colors that are suited for a variety of culinary uses.  Russet potatoes, most commonly found in stores and restaurants, are better suited for the climate of the western US and do not grow well in the eastern states.  For North Carolina's climate and soil, some of the most reliable cultivars include thinner skinned potatoes such as ‘Yukon Gold’, ‘Kennebec’, and ‘Red Pontiac’.

Potatoes grow best in full sun and well-drained, sandy, acidic soil.  Optimal pH is between 4.8 and 5.4.  Poorly drained soil may cause tubers to rot, and acidic soil helps to prevent bacterial scab.  Light soil, if consistently moist, can help the plant grow large, evenly-shaped potatoes.

Potatoes are most often grown from "seed potatoes"– small tubers or pieces of tubers that sprout into a new plant.  Buying certified disease-free seed can help prevent problems such as Potato late blight; grocery potatoes are often treated with sprout inhibitors and therefore may not be reliable for growing.  Before planting, cut seed potatoes so each piece has at least two eyes and let sit outside for a day to let the cut end scab over.  Plant seed pieces 5-6 in apart with the eyes facing up.  Raised beds provide good drainage and containers or grow bags can be suitable for growth so long as they are at least 2 ft deep and hold at least 30 gallons.  As they grow, pile soil or mulch up around the base of the plant– this encourages the growth of more tubers along the submerged parts of the stem.  Do this once the plants are one foot tall and once or twice more throughout the season.  Potatoes may be grown in trenches to make the process of hilling easier.  Tubers will turn green and produce toxic compounds if not sufficiently covered. 

In NC, try to have potatoes planted sometime between mid-February and the end of March; they can tolerate a bit of frost.  Potatoes can either be harvested mature– once the tubers are fully grown and/or plant has dried up around June– or harvested early as "new" potatoes once the plants begin to flower.  These young potatoes still have thin, delicate skins and are considered a delicacy.  New potatoes can be harvested about 7-8 weeks after planting.  Mature potatoes can take 3-4 months before they are ready for harvest.

Insects, Diseases, and Other Problems:  Potato late blight will rot tubers and render them inedible.  Colorado potato beetles lay masses of yellow eggs and the larvae defoliate plants.

VIDEO Created by Elisabeth Meyer for "Edibles, Bulbs, and Houseplants" a plant identification course offered in partnership with Longwood Gardens.