Potatoes

Potatoes require full sun—more than 6 hours per day—it’s important to provide loose soil with lots of organic matter. See “Hilling” below for more information.

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 and 12” apart, in rows 12- 24” apart. If the soil is heavy, plant 2” deep and cover with 2” of mulch.

Most new tubers will form above the original planted tubers, so hilling is crucial for 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.

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.

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

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

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).

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. Once established in your garden, it can affect future crops of potatoes, tomatoes, peppers, and their relatives. It can easily spread to your neighbors’ crops as well. Growing certified seed potatoes is the only way you can assure that these viruses won’t be present.

Market potatoes are also sometimes treated with a sprouting inhibitor which slows shoot growth, resulting in a low yield.

No worries. Grow your potatoes in a container

Fill a 15-20 gallon container half-way up with good draining soil and follow the planting instructions above.