Friday, October 25, 2013

Sweeter with Frost - Spinach

Spinach takes the grand prize of frost hardy and frost sweetened. Spinach will overwinter in Minnesota with a little snow cover. It goes dormant in the freeze up and wakes back up in the spring thaw and will start growing again. The leaves that have been frozen all winter are edible but not good quality, but the new growth is outstanding.

We plant fall and winter spinach between September 1-15 and plant about 3x the amount we would plant for the main summer season. It grows throughout the fall and we harvest as needed. The earlier planting often is harvested twice. The later planting is typically harvested just before freeze up and we often stop harvesting due to snow in early December.

Spinach is always sweet but is especially so after a few light frosts...

You will notice the spinach leaves wilt after an especially hard frost and this is a protection mechanism that the plant uses to keep ice crystals from forming in the cells. The stoma open and give off moisture which condenses on the outside of the plant, this increases the solids (sugar) content of the cells and forms a natural anti-freeze in the cells. The leaves will thaw out and perk up during the day even if frozen solid the night before.

We can harvest when frozen so if we don't have a harvest window during the week (ie. thawed out and we are available to pick), then we might have plenty of spinach but we won't have any at market that week. If we had our spinach in a green house the harvest window is usually much longer as the daily temps under plastic are much higher than in the open.

It has been interesting to grow in the open field all these years both early season and late season. It really challenges your growing skills to create an environment and select varieties that thrive under these conditions.

Even the seed starting mechanism is conducive to the overwintering. The spinach seed will go dormant in the heat of the summer, but will wake up when conditions are good. The plants can then overwinter to the next season to start the cycle all over again.

If you have any questions or suggestions, comment on any post and we'll respond to you.

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