Spinach

Growing Conditions

Spinach is one of the most cold-tolerant vegetables in the garden. It germinates in soil as cold as 35°F and tolerates temperatures down to 15°F–20°F once established. It performs best between 50°F and 65°F. Long days and heat above 75°F trigger bolting rapidly. In northern climates, spinach can be overwintered under row cover for very early spring harvest.

Cold climates: Sow as soon as soil can be worked — 6 weeks before last frost or earlier. For fall, sow 6–8 weeks before first frost. Overwintering under row cover is possible in Zone 5 and warmer.

Warm climates: Fall and winter only. Spinach is nearly impossible to grow in warm-climate summers.

Sowing & Planting

Sow ½ inch deep, 2 inches apart, in rows 12 inches apart. Thin to 4–6 inches. Spinach can be broadcast-sown and thinned, or sown in rows. Germination improves if seeds are soaked for a few hours before planting. In hot soil (above 85°F), germination is poor — refrigerate seeds for 1 week before sowing fall crops.

Care & Maintenance

Keep soil consistently moist. Dry conditions accelerate bolting. Spinach is a moderate feeder — side-dress with compost or a nitrogen-rich amendment if leaves are pale. Avoid overhead watering in humid conditions to reduce disease pressure.

Common Problems

Bolting is the primary challenge in spring. Choose slow-bolt varieties. Downy mildew appears as yellow patches on upper leaf surfaces with gray mold underneath — favor resistant varieties and avoid overhead watering. Leaf miners tunnel inside leaves leaving pale, blistered trails — pick off affected leaves and use row cover to prevent egg-laying.

Harvest

Begin harvesting outer leaves when plants have 5–6 true leaves. Cut outer leaves at the base, leaving the growing center intact. For whole-plant harvest, cut at soil level — plants will often regrow once or twice before bolting. Harvest in the morning for best texture.

Spinach for freezing is best blanched briefly (1–2 minutes), cooled, squeezed dry, and frozen in portions.

Varieties

Savoy types (Bloomsdale) have crinkled, dark green leaves and good cold hardiness. Semi-savoy types (Tyee, Catalina) are more disease resistant and easier to clean. Flat-leaf types are preferred for processing and freezing. For spring plantings, choose varieties labeled as slow-bolt. For fall and overwintering, choose cold-hardy types.