Spinach is a pretty cold-tolerant plant and is perfect for overwintering. When overwintering spinach choose varieties like Giant Winter, Tyee, and Viroflay that handle low temperatures and are more resistant to harsher conditions. Start these seeds about six weeks before the average first frost so that you can use plants about three to four inches wide in size. Use soil that is cooler when starting these seeds to avoid spotty germination caused by dry, warm, late summer soil.
When you choose where you will place your polytunnel or burlap shields, sow the young spinach plants about 1 inch apart. After two frosts you can cover the spinach beds with a combination of compost and straw and then lay the outer layer protective structure. If you live in a more mild winter climate you can forgo the protective structure but use additional straw to shield the spinach plants.
Check moisture levels throughout the winter and keep soil slightly moist. Be cognizant of overwatering to avoid root rot. Root rot causes oxygen deprivation from the plants’ roots, which will stunt growth or kill your crop. As days become longer and temperatures increase you can begin to remove little layers of straw every few weeks.
After all straw has been removed, your spinach crop is just weeks away. Encourage growth by spraying a fish emulsion mixture on your spinach bed. As leaves grow, pluck or cut them from plants and continue to do so as they replenish themselves. Be sure to thoroughly wash spinach leaves before using them in your cooking to avoid ingesting any germs or bacteria.
Cook your spinach with olive oil and garlic in a skillet for a delicious side dish. You can even use your own overwintered garlic (link to overwintering garlic post) for a delightful garden to table snack!