This plant, which is considered native to southwestern Asia, was probably introduced into Europe during the fifteenth century. There is no assurance that it was known to the Greeks or Romans.
With the exception of cabbage (which with propriety may be classed by itself), spinach is the most important crop grown for "greens" in the United States. In the North it was formerly a standard frame crop, but southern competition has made it of little importance there as a forcing crop, compared with lettuce and several other vegetables. It is grown mainly as a spring crop from sowings made in the fall. Spinach is grown on a very large scale about Norfolk, Virginia.
The Rhode Island Experiment Station (R. I. Sta. Bul. 41) has divided the varieties into four groups.
"Plants more or less vase-form, leaves broad, thick and supported by their stalks, so that they do not naturally rest upon the ground. Blossom stalks appear at an early age." The Norfolk Savoy and other varieties belong to this class.
"Plants compact in habit of growth, with leaves conspicuously rounded in outline and formed close to the ground. Tissue firm, color dark green, blossom stalks formed rather tardily. A slow-growing spinach as compared with the other types." The well-known Victoria belongs to this class.
"Plants large, leaves long and spreading out upon the ground, ends and lobes of leaves more or less pointed. A highly prized type of spinach, both for spring and fall planting, on account of its large size and rapid growth." Long Season is a good representative of this class.
"Plants variable, leaves often with long and slender stalks and rather narrow blades. Seeds with hornlike projections. This kind of spinach is not readily sown with ordinary seed drills." Prickly Seeded is a standard variety of this group.
Group V. New Zealand Spinach (Tetragonia ex-pansa) and Group VI. Mountain Spinach (Atriplex hor-tcnsis) are not generally known among vegetable growers.
A very rich, constantly moist soil is required to grow a heavy crop of spinach. In soils of moderate fertility the plants become spindling and the production light. Composted stable manures are especially valuable. The fertilizer employed should contain a high percentage of nitrogen. Mixtures used at Norfolk supply about 8 per cent of nitrogen, 2 to 5 per cent phosphoric acid and 2 per cent potash. They are used at the rate of about one ton an acre, applied in portions at different times throughout the season. The general practice is to make the fall sowings in low beds, 5 to 9 feet wide. This method provides perfect surface drainage. The rows, which should be 10 to 14 inches apart, are drilled lengthwise of the beds and the plants thinned 4 to 6 inches apart. It is important to sow in good time, so that the plants will become thoroughly established before winter. September 25 is the favorite time for sowing at Norfolk, although drilling begins about September 1 and continues until November 15. From 15 to 30 pounds of seed are required to the acre. Frequent tillage with the wheel hoe is just as essential as for other cultivated crops. In the North a mulch of manure or other material is valuable in affording winter protection, although in many districts this is not considered necessary. A push or shuffle hoe is often used in cutting the roots when the crop is gathered. The plants must be trimmed of dead leaves to secure attractiveness when placed on the market. Half-barrel hampers and light ventilated barrels are generally used in marketing the southern crop. Early summer pickings may be secured in the North by sowing as soon as the ground can be prepared.