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.