Prepare the soil with aged manure about a week before planting, or, you may wish to prepare your spot in the fall so that you can sow the seeds outdoors in early spring as soon as the ground thaws.
If you live in a place with mild winters, you can also plant in the fall.
Although seedlings can be propagated indoors, it is not recommended as seedlings are difficult to transplant.
Spring plantings can be made as soon as the soil can be properly worked. It’s important to seed as soon as you can to give spinach the required 6 weeks of cool weather from seeding to harvest.
Select a site with full sun to light shade and well-drained soil.
Sow seeds ½ inch to 1 inch deep, covering lightly with soil. Sow about 12 seeds per foot of row, or sprinkle over a wide row or bed.
Soil should not be warmer than 70º F in order for germination.
Successive plantings should be made every couple weeks during early spring. Common spinach cannot grow in midsummer.
For summer types, try New Zealand Spinach and Malabar Spinach.
Plant in mid-August for a fall crop, ensuring that soil temps are cool enough.
Gardeners in northern climates can harvest early-spring spinach if it’s planted just before the cold weather arrives in fall. Protect the young plants with a cold frame or thick mulch through the winter, then remove the protection when soil temperature in your area reaches 40º.
Water the new plants well in the spring.
Fertilize only if necessary due to slow growth, or use as a supplement if your soil’s pH is inadequate. Use when plant reaches ⅓ growth.
When seedlings sprout to about two inches, thin them to 3-4 inches apart.
Beyond thinning, no cultivation is necessary. Roots are shallow and easily damaged.
Keep soil moist with mulching.
Spinach can tolerate the cold; it can survive a frost and temps down to 15ºF.