Fingerling Potatoes Field Test
Napa County Master Gardeners began field testing spring and fall vegetable crops 10 years ago. Summer squash, broccoli, cherry tomatoes, bush beans and sweet peppers are just a few of the vegetables planted by Master Gardener field testers. The purpose of these tests is to determine the best varieties for the home gardener in Napa Valley. Each participant maintains detailed records about yield, pest resistance and other performance factors.
Our test gardens encompass many microclimates, soil types and water sources. The gardens range from Angwin and Calistoga in the north to East Napa and Browns Valley in the south. With such widely varied testing grounds, we can provide the gardening public with a realistic evaluation of vegetable types. Our results, past and present, will be posted on our website (see address below) in the near future.
Our focus this year is fingerling potatoes. These small, elongated, and sometimes colorful potatoes are creating new menu options for restaurant chefs and home cooks alike. Like all potatoes, fingerlings trace their roots to the Andes mountains of Peru. Most varieties have red or yellow skin and waxy yellow flesh. One of the fingerlings chosen for field testing, the Purple Peruvian, is an exception. It has purple flesh and a mealy texture when cooked.
We have selected three varieties for field testing. 'Russian Banana' is considered among the easiest to grow. It is banana shaped, long and slender, with firm yellow flesh and great flavor. A late variety, it is said to yield heavily and to resist disease. 'Purple Peruvian' is a small to medium tuber with purple flesh. Another late variety, it is recommended for frying. 'Rose Finn Apple' has rose-colored skin and deep yellow flesh. The texture is firm, so it is good for roasting. Its vigorous upright vines produce a late harvest.
Local nurseries are usually out of seed potatoes by this time of year. However, fingerlings are still available at Ronnigers Potato Farm (www.ronnigers.com).
Plant seed potatoes after the last frost in your area, typically between March 1 and June 1. Choose a location with full sun. Potatoes do not grow well in clay soil, which Napa Valley certainly has, so you will probably need to dig in some amendments, such as organic mulch or compost plus a 10-10-5 fertilizer. Break up the soil to improve drainage.
Prepare six-inch-deep furrows in rows at least three feet apart. Plant the potatoes in the furrows, spacing them six to ten inches apart. Cover with soil and water well, then water deeply approximately once a week.
In four to six weeks, when the leafy potato greens are a few inches high, mound soil around the stems, almost to the top of the leaves, to provide more room for the tubers to grow. Keep mounding soil over the new growth until blossoms appear. The potatoes will form on these buried stems. Mound soil over any exposed potatoes to prevent them from turning green. Keep on top of weeds.
Fingerlings will be ready for harvest after approximately four months. When the vines begin to yellow and dry, the crop is ready for digging.
For more information on growing potatoes, contact the University of California Cooperative Extension office (address and phone number below) and ask for the "Healthy Garden Tips" handout on growing potatoes in Napa County. For additional assistance in planning and planting your summer vegetable garden, attend the free Master Gardeners' "Container Vegetable Gardening" workshop on Saturday, May 12, from 9:30 a.m. to 11:30 a.m., at Connolly Ranch, 3141 Browns Valley Road at Thompson Avenue in Napa. This workshop will be repeated at the Napa Valley College Upper Valley Campus in St. Helena on Saturday, May 19. To register, call 707-253-4221.