After growing North Coast vegetable gardens for a dozen years now, we can count on several surefire crops, and one of them is a steady supply of potatoes.
What's not to like about potatoes? Planted from seed, they are quick growers, do well in most soil conditions and can be stored without much preparation. When you eat them, you get a starch-rich treat that brings trace minerals, protein and vitamin C into your diet.
When considering just which potatoes to plant, choose your varieties carefully - the Oregon State University Extension Service suggests the following:
For red potatoes, try "Red Pontiac," "Norland," "Red La Soda" and "Cranberry Red." For white potatoes, the Extension Service recommends "Norgold Russet," "Russet Burbank" and "Superior." Yellow potato varieties that prove successful in our coastal gardens include "Yellow Finn" and "Yukon Gold." If you are looking for a specialty potato, you might consider the blue-skinned "All Blue." Likewise, fingerling potatoes, such as "Amandine" and "Russian Banana" are popular for salads, roasted or steamed. Many of the varieties are available locally at nurseries and garden centers. A good mail order source is Ronnigers Potato Farm, an Idaho operation that carries seed potatoes from around the world. The catalog information is at the end of this column.
Consider the time span from planting to maturity when selecting a variety. "Norland," for example, may mature in 80 to 90 days, compared with 120 days or more for "Russet Burbank." Early-maturing varieties are a better choice for "new" potatoes, but late-maturing varieties store better because they resist sprouting and shriveling in storage.
Also, select a variety suited to the method of cooking you prefer. While the leading United States variety, "Russet Burbank," is excellent for frying and baking, it often is inferior to "Kennebec" or "Red Pontiac" for boiling. Some also consider baked "Russet Burbank" tubers too dry. Many home gardeners prefer to grow an all-purpose variety such as "Kennebec," while others grow several varieties for specific uses.
The ideal seed piece is blocky in shape, has as few cut surfaces as possible, is slightly larger than a golf ball and has two or more "eyes" or buds. When cut properly, 10 pounds of seed potatoes will produce about 100 seed pieces, enough to plant about 100 feet of row. A 100-foot row should yield between 200 and 400 pounds of usable potatoes if the crop is allowed to mature fully.
Potatoes can be planted from March until mid-June, but most gardeners prefer May. Due to wet weather, western Oregon gardeners normally do not plant before late April or early May. I have to admit, with our relatively dry past few weeks, our potato seeds are in the ground, and we have plants. There's still plenty of time to plant potatoes, if you figure that our cool growing season lasts between 190 to 250 days.
Potatoes do best on fertile, well-drained loamy or sandy soils but can be grown on virtually any soil if high yields and smooth appearance are not essential. In fact, you might not want to plant your potatoes in your most amended and fertile beds. That's because soils with a high pH (alkaline) or extremely high organic matter cause severe scab problems in susceptible varieties, including most round whites and reds.
When you plant, work the soil to a depth of 6 to 8 inches and plant the potatoes about a foot apart. Cover them with 2 to 4 inches of soil. The seedbed does not have to be perfectly smooth as is required for small-seeded crops. Excessive tillage actually can cause the soil to seal over after heavy rains, leading to seed piece suffocation and death. When the first green leaves emerge and the stems are about 8 inches tall, gently work the soil around the stem into a hill, leaving about 4 inches of the stem exposed. This cools the soil and creates a place for the tubers to develop.
Fertilizers normally are applied at or shortly before planting either by broadcast or band applications or a combination of the two. Many gardeners hand broadcast the entire amount and work it into the top 3 or 4 inches of soil by rototilling or raking. Never place fertilizer on or directly above the seed pieces; the fertilizer salt will dehydrate and damage or kill the seed pieces and developing roots and shoots.
Alvin Mosley, potato expert with the OSU Extension Service, has spent more than three decades studying the best ways to grow, harvest and store potatoes. Mosley says red potatoes don't keep as long as yellow or white varieties. And thin-skinned potatoes don't last as long in storage as those with thick skins, such as "Russets." Because of their thick skins, "Russet" varieties are less susceptible to injury during harvest than reds or whites. The thick "Russet" skins generally also are resistant to common scab.
Once your potatoes have come up, toughen them for storage before harvest by reducing water, once they have flowered. Let the vines die all the way back before you harvest them.
Sort out and cull your injured and diseased spuds before storing them long-term. Clean your potatoes and make sure the potatoes are completely dry before placing them in storage. Cure your newly dug and cleaned potatoes for a week to 10 days in moderate temperatures and high humidity and they will last longer.
Once they are cured, sort the potatoes, putting the best ones in well-ventilated containers. Store your best tubers in a dry room with constant temperature of 35 to 40 degrees and moderate humidity. Make sure to keep them dark, as light will turn them green and make them unfit for table use. Discard potatoes with an excessive amount of greening. Under these conditions, well-matured potatoes will stay in good condition for seven to eight months.
Two good sources for potato growing information are available. To learn more about how to plant and grow potatoes, you can view read OSU's EC 1004 on the Extension and Station Communications Web site. Select "Publications and Videos," then "Gardening." You'll find EC 1004 under "Vegetables." Or you can order it for $1 per copy plus $3 shipping and handling per order. Send your request and a check or money order payable to OSU to: Publications Orders, EESC, 422 Kerr Admin., OSU, Corvallis, OR 97331-2119.
Meanwhile, Ronnigers specializes in organically-grown seed potatoes, and new and heirloom cultivars available this season include "Anoka," the winning white potato at Rodale's Organic Gardening Taste-Off. It's the earliest of the white varieties. Catalogs are available by writing Ronnigers Potato Farm, HCR 62 BOX 332AP, Moyie Springs, ID 83845 or by e-mailing firstname.lastname@example.org
Cathy Peterson belongs to the Clatsop County Master Gardener Association. "In the Garden" runs weekly in Coast Weekend. Please send comments and gardening news to "In the Garden," The Daily Astorian, P.O. Box 210, Astoria, OR 97103 or online to email@example.com