The Dirt Issue 37 – All About Potatoes

Posted on March 26, 2019
Share It:

Share It:

Skagit County’s #1 Crop
By far the most popular vegetable grown in the U.S., potatoes have been grown in Skagit County from the earliest days of European settlement. The first recorded crop of cultivated potatoes was planted on March Point in 1853 and potatoes were a staple of most kitchen gardens from then on. As a major agricultural crop, however, potatoes really came into their own after market forces caused closure of processors for such crops as peas in the late 80s. Today potatoes are the top monetary crop produced in the county, earning about $60 million in annual sales. Currently that volume is achieved from about 12,000 acres planted per season. Considering most farmers follow at least a three-year crop rotation program (it can be as much as five—the longer, the better), that means a minimum of 36,000 acres is made available for potato rotation in Skagit County.

Washington State, as a whole, produces 20 percent of the potatoes grown in the U.S. The State has two distinct growing regions, the Columbia Basin and our own Skagit County. It’s Skagit County, however, that is renown for premium red, yellow/gold, white and blue potatoes.

A Nutritional Powerhouse
Potatoes are native to the high Andes of Peru and Bolivia. There is evidence that the potato, in hundreds of varieties, has been cultivated there for at least 4,000 and possibly as much as 7,000 years. Spanish conquistadors were the first to bring potatoes to the European continent and historians cite 1621 as the date they were first brought to North America.

Potatoes have evolved to be particularly adept at storing starch and proteins. When we eat a potato, the starch provides energy without spiking blood sugar. According to the Washington State Potato Commission, a medium-size potato weighing 5.3 ounces contains 45% of the daily value of vitamin C (in fact, the Spanish soon discovered that eating potatoes when at sea prevented scurvy; they just didn’t know why). At 620mg, the potato also contains about 200mg more potassium than a similar-size banana. Potatoes also contain, in terms of our daily value requirements, 10% of vitamin B6 and 8% of fiber as well as essential amino acids (proteins) in similar proportion to human needs. Potatoes are considered nutrient-dense in that they provide a great amount of nutritional value for only 110 calories. Researchers at the University of Washington state that potatoes provide the most nutrients per penny.

Besides the nutritional benefits, potatoes have almost no limit to their culinary uses. Suitable for any meal of the day and capable of relatively long term storage, potatoes have well earned the right to be the top non-grain food staple in the world and fourth overall behind corn, wheat and rice.

How It Grows
Skagit County boasts rich soil and a mild marine climate. Our warm, long days and cool nights are perfect potato growing conditions. But what we don’t have is the long growing season that they enjoy in the Columbia Basin. Because of this restriction, most potatoes successfully cultivated in the county produce their harvest over a 90-day growing season. Some cultivars, in some areas, can grow over as many as 110-days, but that is the typical limit. These early-maturing, mostly European varieties produce the size and yield our farmers need in the time our farmers have.

Once the spring soil is dry enough and warm enough—55° F is ideal—the growing season can begin. Around here that can range from early April to mid-May. In the U.S., all commercial potatoes are grown from certified seed. To be certified, seed potatoes must meet rigid national standards that are strictly enforced to ensure elimination of potential pathogens, varietal purity, and unquestionable sanitation.

In Skagit County, partly because of the weather and partly due to the makeup of the soil, seed potatoes tend to be planted shallowly, 3 to 4-inches deep. Once the main stem and leaves emerge above ground and reach a certain height, the farmer “hills” the plants by mounding soil over about half of the plant’s height. As the plant continues to grow, this hilling is done again. All this effort is to keep the potatoes themselves from being exposed to direct sunlight. Potatoes, of course, grow below ground. They are not part of the plant’s root system, even though they are sometimes referred to as root vegetables, but are thick, short underground stems known as tubers. These tubers are nutrient storage organs for the plant, but potatoes for us. The potatoes grow both downward and outward which causes the soil surface to be pushed up and crack. This can expose the potatoes to direct sunlight. In a purely natural process, sunlight makes potatoes turn green and green potatoes are no longer eating potatoes. So, to keep potatoes storing all their goodness, they are hilled until just before the plant flowers.

A Sight to Behold
It’s a beautiful sight in Skagit County when the potato fields are in bloom. It’s a beautiful sight to the farmer because it marks the point when the plant stops growing (it now has as many leaves as it will ever have) and the food produced by the leaves is directed downward to be stored in the tubers. Thus begins the peak time for tuber formation.

Once the tubers mature to a marketable size—or the growing season is coming to an end—the plants are killed off, either with a desiccant or by mowing down. The tubers are left in the ground for 10 days to as much as 3 weeks. This period is known as skin set and it gives the tuber the time it needs to grow a bit more (as much as 3 to 4%) and develop a tougher skin. At harvest time—ideally the first week in October—the skin should be able to withstand being mechanically dug out of what may be dry and somewhat abrasive soil.

Prior to sizing, grading, packing and storage, the newly dug potatoes rest in controlled conditions to allow the skin to cure. This step helps potatoes store longer.

Market preferences determine what potatoes go where. No. 1s are typically sold in groceries, while those with a few nicks and scrapes are suitable for processing into the many potato products we all love.

So, next time potatoes are on your shopping list, look first for those from Skagit County. Now that you know how they’re grown, their quality and flavor makes perfect sense.