There are many unsubstantiated stories of why, during the depths of the Great Depression, cartoonist E.C. Segar chose the vegetable spinach to give his comic strip character Popeye the Sailor superhuman powers. Quite likely, it was his attempt to prompt children of all ages to eat more of this nutrient powerhouse. During that era, the diet of the average American was lacking in essential vitamins and minerals, and the nutritional well-being especially of children was of great concern.
Segar's tactic worked. Not long after Popeye began gulping down a can of spinach when he found himself in the midst of a perilous situation, the consumption of spinach began to skyrocket. In fact, during the 1930s, spinach consumption was said to have increased by 33 percent. Perhaps more remarkable is the report that children surveyed at that time listed spinach as their third favorite food. While we now know that certain of spinach's nutrients are not as available to humans as originally thought, it still is considered one of the most nutrient-dense of all foods whose health benefits still are being discovered.
Spinach (Spinacia oleracea) is a leafy green vegetable in the Chenopodiaceae plant sub-family and is thought to be native to ancient Persia (central and western Asia). From there, it migrated to India and ultimately to China, where it was mentioned as a food source in the 7th century. Arabs brought spinach to Sicily during the 9th century, and to the Mediterranean region by the 10th century. It was during that era that three textbooks made mention of spinach, one of them being a medical text which hailed it as the "chieftain of greens".
The Germans knew about spinach by the 13th century and, by the 16th century, it found its way to France and England. Catherine de' Medici, queen of France in 1533, was so fond of spinach that she ordered it to be served at every meal. Queen Catherine was born in Florence and, in reference to that fact, dishes made with spinach often are referred to as "Florentine."
Spinach made its way to America when the first settlers arrived and by the 19th century seed catalogs listed several varieties available commercially. Breeding work with spinach began in earnest in the early part of the 20th century when plant geneticists started selecting and hybridizing spinach varieties with improved disease resistance and those that are slower to bolt (flower). Botanically, spinach is a long-day plant that responds to long periods of uninterrupted light by flowering. Hot weather along with drought tends to hasten the response which, in turn, leads to a rapid reduction in table quality.
Spinach is a hardy, cool-season vegetable that does well at our latitude from March through May and again September through November. Fall plantings often survive our winters if given some protection such as with a cold frame of hotbed. Early spring/late winter plantings can be seeded over frozen ground or snow. Most gardeners, however, delay planting until about six weeks before the last frost or when soil temperatures have reached at least 40o F. The latter is considered the minimum temperature at which spinach seeds will germinate.
Plant seeds in a well-drained garden loam that has been fertilized according to soil test results. A slightly acidic soil (e.g., pH of 6.5) is preferred. Spinach has a relatively deep tap root but a shallow network of "feeder roots". Therefore, a combination of good drainage along with adequate water retention is important for optimal growth. The addition of well-decomposed organic matter to the soil will aid in developing this combination of properties in the soil. If manure is used, make certain it has been properly composed to avoid the possibility of bacterial contamination.
Sow spinach seeds in rows 18 inches apart and thin later to a distance of about two to four inches between plants. Thinning does not need to be practiced if the entire crop is harvested at once, rather than removing a few leaves at a time. Covering seeds with a soilless potting mix tends to prevent soil crusting which can inhibit seedling emergence.
Once the planting is established, weed control and adequate amounts of water probably are the two most important requirements to assure a good crop. If plant growth is slow or color light green, a light side-dressing of nitrogen is recommended. Occasionally, flea beetles will chew small holes in spinach, but their numbers usually do not build to the level of warranting intervention.
Spinach can be harvested as soon as the oldest (outer) leaves are large enough to use. This usually occurs 40 to 50 days after seeding when the plants (which morphologically are rosettes) have at least five or six leaves present and the oldest leaves are about three inches in length. If the entire plant is to be harvested at once, wait until the first seed stalk appears to do so.
The nutrient content of spinach decreases fairly rapidly after harvest. Therefore, refrigerate immediately after harvest. Refrigerated spinach can be successful stored for up to five days. Since excessive moisture tends to favor storage diseases, spinach leaves should be thoroughly dry if washed before storage. Alternatively, refrigerate spinach immediately after harvest and wash thoroughly just before use.
Horticulturists recognize three different types of spinach according to leaf morphology: savoy, semi-savoy and smooth-leafed. Many of the varieties developed for home gardening are of the savoy ("crinkly leafed") type. 'Bloomsdale Long Standing' is an old savoy variety that still retains a great deal of popularity among home gardeners. 'Melody' is a popular smooth-leafed type, while 'Tyree' enjoys success as a semi-savoy variety.
History does not record why spinach gave Popeye superman-like powers. However, nearly a century later, we know much more about the benefits of spinach in the human diet. In addition to being a potent source of vitamins, minerals and dietary fiber, spinach contains other phytonutrients important for human health. According to the World's Healthiest Foods (www.whfoods.com ), spinach contains cancer-fighting agents including flavonoid glucuronides. It also is an excellent source of the antioxidants lutein, zeaxanthin, neoxanthin and violaxanthin. All are anti-inflammatory in nature and can be helpful in preventing damage to human cells by eliminating free radicals. The latter has been indicated by some research to reduce incidence of heart disease, arthritis, stroke and other human disease, including cancer.
REVISED: April 7, 2020