Digging for Gold (or Purple) Potatoes

by Marcia Fein

If you shopped at the Farmers’ Market last summer, you may have enjoyed some lovely potatoes with fairyland names and novel shapes and colors. I remember fondly a steaming bowl of Russian Banana and Red Thumb, dressed in olive oil and garden-fresh snipped parsley. I vowed once again to grow my own. Fresh from the earth, your own potatoes can be superior to most grocery store spuds in the same way home grown tomatoes are better than the red baseballs they sell in winter. You can store potatoes for weeks or months without canning, drying or freezing, too. What a deal!

Choices

The variety of potatoes available to the home gardener today is amazing. One mail order catalogue lists over 80 named varieties. They come with skins of purple splashed in violet, pale pink to brilliant red, white with pink-red swirls, golden yellow to red-brown, buckskin with splotches of pink or purple around the eyes, and the ever popular white. Spud contours include round, flattened, pear, oval, bumpy, smooth, oblong and fingerling.

"Enough about looks!" you say. "What do they taste like?" Well grown and harvested at the right time most are sweet and nutty. In general taste is related to texture is related to color. Potatoes come in three basic textures.

  • Moist - Most of the red skinned potatoes are moist and taste best steamed, especially the ones with white flesh. Those with yellow or red flesh can also be very good fried.
  • Waxy - Most yellow fleshed potatoes, which may have tan, yellow-tan or rose-tan skin, are waxy. This group includes almost all of the fingerlings and tastes great prepared in the widest variety of ways. I like the fingerlings steamed or roasted, but Yellow Finn and Yukon Gold, roasted, fried or baked.
  • Dry- Mealy potatoes are excellent bakers. These include all the russets (with white flesh), and the blue skinned, white and blue fleshed potatoes. Most people also like these mashed.

Culture

The potato, Solanum tuberosum, will grow in any moderately fertile, well drained soil in full sun. It is a heavy feeder with a wide and 12 inch deep root system. It will do best in very well composted soil, high in nitrogen and potassium. Given our heavy soil a raised bed is ideal. It is sensitive to both temperature and day length, with the cool, lengthening days of spring favoring vine growth and the shorter days in late summer and fall, the development of tubers. Ideal daytime temperatures are 60-65 degrees and night, 45-55 degrees. Late February to early May is prime planting time. Some gardeners plant a second crop in August under a thick mulch to cool the soil.

Planting

Select your seed potatoes from certified disease-free stock found at local nurseries or through mail-order catalogs. Do not use potatoes from the grocery store since they may be diseased and sprayed with a chemical to inhibit sprouting. The best size tuber to plant is two to four ounces, like a medium egg. These may be planted whole, reducing the risk of rot incurred by cutting larger potatoes into pieces. If you do use large seed potatoes, cut them into egg-sized pieces with two or three strong eyes and let the pieces air in the shade for a day, or dust the cut sides with sulfur, wood ash or lime, to reduce rot. Some gardeners pre-sprout, or "chit" the seed pieces before planting, but this necessitates very careful handling at planting time.

If your soil is dry, irrigate a few days before planting. Then dig a trench 8-12 inches deep and place the pieces at the bottom, 9-18 inches apart. While authorities differ on the details, most agree that wider spacing promotes a higher yield per plant. Your next row can be two to four feet away. Cover the pieces with two to four inches of soil and wait for sprouts to appear. As the plants grow, gradually fill in the trench with soil around the plant. Called "hilling" this results in higher tuber production and prevents sunscald. Most roots and all tubers will develop at and above the level where you plant the seed potato.

Pests and Disease

Potatoes are vulnerable to fungal diseases, especially Phytophthora infestans (late blight), so avoid moisture that stays on the leaves and avoid handling them unnecessarily. Remove and destroy any infected plant. Gophers love potatoes and moles can break off delicate roots as they tunnel through the soil in search of insects and worms. If these are problems where you garden you may want to line the trench with chicken wire or hardware cloth before you plant. Since gophers eat only the tubers, not the feeder roots, the plants may appear undamaged above ground, hiding the loss until harvest time.

Growth and Harvest

Since potatoes are heavy feeders you may want to supplement your fertile soil with a bi-weekly dose of fish emulsion, especially during the first two months of growth. Potatoes require moderate to heavy water, one to two inches per week, preferably through drip irrigation to reduce fungal disease. The soil should be kept evenly moist.

If you want "new," low starch, potatoes you can dig a few spuds with your hands after about 60 days for early potatoes, 75 for mid-season and 90 for late varieties. Leave the main, storage, harvest until vines have begun to yellow. At this point, withhold water for about two weeks, cutting off and removing the vines after a few days. After eight to ten days, dig a few to see if the skins have thickened sufficiently and leave the rest in the ground another few days if needed. Harvest by lifting the soil in the root zone with a fork or spade and pull out your gold (or purple) nuggets. Brush off the loose dirt and store the tubers cool, dark and humid. Enjoy!

Varieties and Sources of Seed Potatoes

My picks for taste and productivity (but I’ve only tried 25 varieties!) are fingerlings: Peanut, Purple Peruvian, Red Thumb, Rose Finn Apple (AKA Ruby Crescent), Russian Banana; and other: Bintje, Buffalo (AKA Red Ruby), Desiree, German Butterball, Viking Purple, Yellow Finn, Yukon Gold.

  • Common Ground Garden Supply, 559 College Avenue, Palo Alto 650.943.6072
  • Irish Eyes/Garden City Seeds, P.O. Box 307, Thorp, WA 98946
    877.733.3001
    www.irish-eyes.com
  • Territorial Seed Company, P.O. Box 158, Cottage Grove, OR 97424-0061
    541.942.9547
    www.territorialseed.com
  • Peaceful Valley Farm Supply, P.O. Box 2209, Grass Valley, CA 95945
    888.784.1722
    www.groworganic.com
  • Seed Savers Exchange, 3076 North Winn Road, Decorah, IA 52101
    563.382.5990
    www.seedsavers.org
  • Johnny’s Selected Seeds, 184 Foss Hill Road, Albion, ME 04910
    207.437.4301
    www.johnnyseeds.com

MASHED POTATO FUDGE

  • 1/2 cup cooked, potatoes mashed
  • 2 tablespoons soft butter or margarine
  • 1 pound confectioners' sugar
  • 3 squares cooking chocolate, softened and melted
  • 1 teaspoon vanilla dash of salt

Put mashed potatoes into a mixing bowl. Add soft butter and mix. Add confectioners' sugar, mix well. Add vanilla to melted chocolate, then add with salt to the mashed potato mix. Chill. Coconut may be added. Cut into bars or squares. Place in refrigerator to chill. Slice 1/4-inch thick.