Spinach grows in a wide range of soils if moist and fertile, but is sensitive to acidity; pH should be at least 6.0, preferably 6.5-7.5.
Spinach germinates best in cool soil. Begin sowing in early spring as soon as the ground can be worked. Summer sowing in soil over 85°F (30°C) risks low or erratic germination.
If sowing has to be done during warmer weather, irrigating can help cool the soil and improve germination. Sow in mid to late summer for a fall harvest.
Spinach can also be planted from late summer until freeze-up in protected structures for fall, winter, and spring harvest. Using floating row covers offers additional winter protection.
PLANTING AND HARVEST
For Baby leaf: Sow in a 2-4" wide band, 3/4" apart, about 40 seeds/ft. Clip small leaves in 3-5 weeks, depending on the time of year and speed of growth. Triple-rinse leaves, sort out cut and broken leaves and package.
For a continuous supply, sow every 7 days. For bunching and full size: sow 10 seeds/ft., 1/2" deep, rows 12-18" apart. Harvest spinach full size but before bolting, cutting just below root attachment for "rooted spinach", or cut higher for "clipped spinach".
STORAGE Store at 32°F (0°C) and 95% relative humidity for 10-14 days.
AVG. DIRECT SEEDING RATE For full-size leaves: 10M/1,000', 290M/acre at 10 seeds/ft. in rows 12-18" apart. For baby leaf: 1M/25', 25M/125', 1,200M/acre at 40 seeds/ft. in rows 18" apart.