When to Plant
The first planting can be made as soon as the soil is prepared in the spring. If the soil was prepared in the fall, seeds can be broadcast over frozen ground or snow cover in late winter and they will germinate as the soil thaws. Plant successive crops for several weeks after the initial sowing to keep the harvest going until hot weather. Seed spinach again in late summer for fall and early winter harvest. Chill seeds for summer or fall plantings in the refrigerator for 1 or 2 weeks before planting. In southern locations, immature spinach seedlings survive over winter on well-drained soils and resume growth in spring for early harvest. With mulch, borderline gardeners should be able to coax seedlings through the winter for an early spring harvest. Spinach can be grown in hotbeds, sunrooms or protected cold frames for winter salads.
Spacing & Depth
Sow 12 to 15 seeds per foot of row. Cover 1/2 inch deep. When the plants are one inch tall, thin to 2 to 4 inches apart. Closer spacing (no thinning) is satisfactory when the entire plants are to be harvested. The rows may be as close as 12 inches apart, depending upon the method used for keeping weeds down. In beds, plants may be thinned to stand 4 to 6 inches apart in all directions. Little cultivation is necessary.
Spinach grows best with ample moisture and a fertile, well-drained soil. Under these conditions, no supplemental fertilizer is needed. If growth is slow or the plants are light green, side-dress with nitrogen fertilizer.