Spinach is a cool-weather vegetable related to beets and Swiss chard. A fast-growing plant, it yields many leaves in a short time in the mild weather of spring and fall. When growing spinach, the trick lies in making it last as long as possible, especially in the spring, when lengthening days shorten its life. Although it prefers full sun, spinach will still produce a respectable harvest in partial shade.
Soil, Planting, and Care
Spinach grows most quickly in well-drained soil rich in organic matter such as compost or composted manure and with a pH of 6.5 to 7. In order to grow spinach twice a year, plant it about 4 to 6 weeks before the last frost in the spring, and again 6 to 8 weeks before the first frost in the fall. Space plants 12 inches apart; this gives leaves room to reach full size. For the most tender leaves, encourage spinach to grow fast and without interruption by using nitrogen-rich soil amendments such as blood meal, cottonseed meal, or composted manure or timed-release fertilizer such as Miracle-Gro® Shake ‘N Feed® Tomato, Fruits & Vegetables Plant Food regularly for quick growth.
In the spring, plants will grow tall and bloom (called bolting) as soon as the days are longer than 14 hours. Heat also speeds up bolting, since spinach prefers temperatures between 35 and 75 degrees. Our variety is slow to bolt, which is a real bonus for gardeners who don’t have the luxury of long stretches of mild weather.
Because it bolts in the lengthening days of spring, spinach is an especially popular crop for fall, when days are short and cool. Plants are very cold-hardy, tolerating temperatures as cold as the teens to low 20s once they are well established. This quality makes them great for overwintering over in zones 8 and southward.
In cold climates, some gardeners plant spinach in a cold frame or cover plants with hay and leave them all winter; they’ll be first to produce a very early spring harvest.
Heat and long days will end your crop, so plant as mentioned above. Pests that enjoy spinach include flea beetles, spider mites, and aphids, which feed on the leaves. Diseases that attack plants are downy mildew (a mildew that may appear during cool, moist weather) and white rust (which causes white spots on the leaves).
Harvest and Storage
Spinach leaves are ready to harvest as soon as they are big enough to eat. Harvest by removing only the outer leaves and allowing the center leaves to grow larger; this will allow the plant to keep producing. Picking the outer leaves also gives the advantage of briefly delaying bolting. In spring, when plants are about to bolt, pull the entire plant at once to enjoy the leaves before they become bitter.