when the plants have four true leaves.
Deep cultivation and hand pulling weeds can harm spinach roots, so it’s advisable to spread a light mulch along the rows to suppress weeds and some insects.
Water stress will also encourage plants to bolt to seed, so provide enough water to keep the soil moist but not saturated.
Spinach plants form a hefty central taproot, so be sure to loosen the soil to at least a foot in depth prior to planting. Spinach also requires moisture, not excessive, but ample moisture. As with all plants grown for their foliage, a nitrogen-rich soil is also essential.
Sow spinach seed early, as early as 5 weeks before the last frost date or as soon as you can work the soil. If you prepare the soil the previous autumn, you can place the seeds in the thawing ground. In areas with a extended cool spring, make plantings at weekly intervals until mid-May.
In warm climates, spinach should be planted in a shaded area, behind a tall crop such as corn is a good idea. Using cold frames or heavyweight row covers, you can sometimes grow spinach all winter long.
Strawberries are a good companion plant for Spinach as the plants draw nutrients from different levels of the soil, they don’t compete with each another, the spinach will grow taller more rapidly and provides some shade for strawberries.
Planting radishes among your spinach will draw leafminers away . The damage from leafminers to the radish leaves will not harm the radishes growing underground in the relatively short time it takes them to mature. See - Spinach Compatible Plants
Pests are not a major problem when most spinach is growing, in very cool weather that is.
Leaf Miner larvae can burrow inside leaves and produce tan patches. Prevent leafminer problems by keeping your crop covered with floating row cover.
Slugs will feed on spinach leaves.
Aphids will spread a disease known as Spinach blight, it causes yellow leaves and stunted growth. Try to use resistant varieties.
Downy mildew will appear as yellow spots on leaf surfaces and mold on the undersides, it occurs under excessively wet conditions. Reduce the spread of disease spores by not working around wet plants. Try to use resistant varieties.
In 6 to 8 weeks you can begin harvesting from spinach plants that bare at least six leaves 3 to 4 inches long, this of course varies slightly from variety to variety . Harvest by carefully cutting the outside leaves will extend the plants productive life . Harvest the whole crop at the first signs of bolting by using a sharp knife to cut through the main stem just below the surface.
Spinach can chopped and frozen but doesn't store well.