Potatoes

Solanum tuberosum

By SCMG Thomas Glenn

As a youngster I enjoyed baked potatoes and mashed potatoes made from russet potatoes. I wrongly assumed that there was only one variety of potatoes. Since then, I have learned that there are over 4000 edible varieties of potatoes of which only about 100 varieties are sold in stores and commercially marketed. This leaves thousands of varieties for home gardeners to explore the possibilities of growing.

Potatoes were first discovered by the Indians in Peru over 4000 years ago and they have been successfully cultivating and growing them for over 2300 years through mostly organic means. Potatoes are the world’s fourth largest food crop, following rice, wheat and maize. They are tubers which are the fleshy, food-storing swellings at the tip of underground stems, also called stolons.

Potatoes typically have white, brown, purple or red skin and white or golden flesh. While a tremendous number of varieties can be grown successfully in Sonoma County, if you are new to potato cultivation, you may wish to try one or more of the varieties recommended by the California Master Gardener Handbook: ‘White Rose’ (high-yield, large potato with white waxy flesh with moist texture), Kennebec (medium- to late-season high-producing yield, pale yellow skin, white flesh, stores well), ‘Chieftain’ (mid-season, red skin, white flesh, does better in clay soils than others), ‘Norgold Russet’ (early-season medium-producing yield, white flesh), ‘Red Lasoda’ (mid-season yield, red skin, white flesh, stores well), and ‘Yukon Gold’ (early-season yield, gold flesh with dry texture).

Potatoes are grown from pieces of potatoes or eyes sets cut from seed potatoes. Certified disease-free seed potatoes can be purchased from your local garden center. Do not use grocery store potatoes. Cut the seed potato so that there is at least one eye per piece and plant them seven to eight weeks before the last frost. If you dry the potato pieces for one to three days before planting, the cut surfaces will be less susceptible to rot. Potatoes thrive in well-drained loose soil. Plant three inches deep and space six to twelve inches apart. As potatoes grow they need to be hilled. Hilling is done by covering the base of the plant with three to four inches of soil to prevent the potatoes from exposure to light which causes them to turn green. Green potatoes contain a poisonous alkaloid and should not be consumed.

To protect your potato plants from potato diseases and pests, it is recommended that you rotate the potato plot each year, maintain wide spacing and use drip irrigation to keep plant leaves dry. By planting healthy certified seeds and maintaining constant soil moisture you can control early blight and late blight which are fungal diseases that can damage your potatoes.

Look for pests regularly including the flea beetle and aphids. With an insecticidal soap spray, you can control aphids. Fabric row covers can foil flea beetles. A good reference for pest identification and control is the UC Davis Integrated Pest Management page.

Harvest your potatoes once their vines die (late July or August). If you wish, you can harvest early potatoes when they are large enough for table use. Harvest by carefully digging the potatoes on a dry day. Store them in a cool, dark place.

A medium potato is naturally fat free, has only 110 calories, is rich in vitamin C and potassium and is a good source of fiber. There are literally thousands of recipes available for cooking and preparing potatoes.