After a winter spent eating store-bought salad greens, there is almost nothing more delightful than stepping out into the kitchen garden in March and uncovering a bed of ready-to-eat spinach. Overwintering this cold-hardy green is simple—the key is planning, and these easy-to-follow steps will yield a bountiful harvest of spinach come spring.
Cold-tolerant spinach varieties, such as 'Giant Winter' and 'Tyee', overwinter best if the plants are 3 to 4 inches wide by the time night temperatures start to dip toward freezing. Give the plants time to reach this size by sowing the seed 6 weeks before the average first-frost date. Spinach seed often suffers from spotty germination when planted in late summer and fall due to warm, dry soil conditions. Boost germination rates by cooling the soil the week before sowing; just water the bed well and then place a burlap sack over the soil to shade it.
Sow the spinach seeds generously, about an inch apart, and then thin the seedlings to 6 inches once they develop three sets of leaves. Keep the soil consistently moist. After one or two light frosts, cover the spinach with 12 inches of straw mulch. Place a floating row cover over the bed to provide an extra layer of insulation in climates where wintertime temperatures hover at or below freezing for weeks at a time.
Once the days begin to lengthen and daytime temperatures consistently rise above freezing, remove a couple of inches of straw at a time over a period of a few weeks until all the straw has been removed. Kick-start growth by spraying plants with diluted fish emulsion. Begin harvesting leaves regularly when the plants actively put out new growth.
Check out our Spinach Growing Guide.