Can spinach survive winter?

Developing spinach over the winter, which is very rewarding, begins with zone-specific strategies. In USDA climate zones 3-7, I have harvested fresh leaves even under snow, following 6 inches of straw mulch on spinach that was established. ‘Giant Winter' spinach has survived -10°F provided there was protection from the wind and ice melt drain-off.

A client's cold frame in Minnesota generated harvests from the previous winter. She utilizes double-wall polycarbonate panels that she angles to 35 degrees and soil heating cables set to 40 degrees. Remember to ventilate on sunny days. Once temperatures get above 50 degrees Fahrenheit, growth often occurs and the frost comes back to kill overnight.

You can avoid root rot by building raised beds for vegetables and using drip irrigation methods. From my trial, plants had about 90% survival in raised beds as opposed to about 40% in the flat plots. Space the plants about 8 inches apart, as crowding them will keep moisture around the plant. Be sure to test the soil each week- do not water if the soil moisture is less than 6.3.

Snow serves as insulation. A 6-12 inch snowpack over plants that are mulched will insulate the soil better than artificial coverings. Plant cold tolerance was tested in a severe blizzard, and spinach plants that were underneath 18 inches of snow were 15°F warmer than other exposed plants. Only remove excessive snow that is blocking direct sunlight from penetrating the plants.

It's important to give some thought to the spring revival process. When temperatures reach above 35°F, remove the mulch gradually throughout 7 days. And then apply fish emulsion tea to promote growth, as in my 2022 trial the plants with fish emulsion added back 3x more growth than unfertilized plants. Be aware of frost heave; if some of the roots have been pushed up, replant them quickly after the frost is gone!

Read the full article: How to Grow Spinach: 7 Essential Steps for Success