Potatoes

There is nothing like the taste of home-grown potatoes, and they are so easy to grow! A pound of seed potatoes can yield up to 25 pounds of spuds!

Site Requirements

Full sun—more than 6 hours per day—is important. Loose soil with lots of organic matter is ideal. See “Hilling” below for more information.

Planting

If possible, choose seed potatoes the size of an egg, and plant them whole. Large tubers should be cut up into pieces that contain two or more eyes, which are often clustered at one end of the tuber. Use a clean, sharp knife to cut seed pieces. They should be planted within a few days after being cut.

Plant when soil temperatures are between 50° to 70°F, generally between mid-March and the end of May in Portland. Plant seed potatoes 4-6” deep, 12” apart, in rows 12- 24” apart. If the soil is heavy, plant 2” deep and cover with 2” of mulch.

Hilling

Most new tubers will form above the original planted tubers, so hilling is crucial to getting a good yield. Sprouts will emerge in about 2 weeks after planting. When the stems are about 8” high, gently add soil around the vines until only 4” are exposed. Use soil, compost, or any other light but moisture retentive material. Repeat the hilling process every time the vines reach 8” tall.

Culture

Potatoes need regular water to produce a good yield. Once the plants begin to turn yellow and die back, they do not need to be watered.

Add a balanced granular fertilizer such as EB Stone Organics Tomato & Vegetable at planting time. Apply regularly, as directed on the package, from the time the sprouts emerge until the plants begin to turn yellow.

Harvesting & Pruning

Once the plants turn completely yellow and die back, the potatoes will be ready to harvest. Leave potatoes in the hill for about 2 weeks after vines have died down. This allows time for skins to “set”, which increases storage ability.

Carefully dig using a digging fork or spade to avoid slicing potatoes in half!

Storage

Potatoes keep best in the dark at 36° to 40°F, with enough humidity so they don’t dry out. Store in paper or net bags to promote good air circulation. Light or warmth promotes sprouting and can turn potatoes green (which should not be consumed).

Why choose seed potatoes?

Potato viruses are very common, and can be present in potatoes bought from stores or markets. The most persistent virus that affects potato-family crops is spread by aphids, and, once established in your garden, can affect future crops of potatoes, tomatoes, peppers, and their relatives, and can easily spread to your neighbors’ crops. Growing certified seed potatoes are the only way you can assure that these viruses won’t be present.

Market potatoes are also sometimes treated with a sprouting inhibitor which retards shoot growth, and can result in a low yield.