Our Winter Crop Plan

We’re near the end of the outdoor growing season but our winter tunnel growing season is just kicking into production. This week I want to go over our winter crop plan. I’ll go over the various crops we’re growing in our tunnels this year including two new varieties that we’re trialing for winter hardiness.

Lettuce

We’ve found that our lettuce mix varieties are actually incredibly cold tolerant and can handle temperatures as low as 15* inside the tunnel before we start to see damage to the plants. Most seasons this means we will have lettuce mix available for November and December. We also trialed a new-to-us butterhead lettuce variety called Landis Winter that is even more cold tolerant than our lettuce mix but the trade-off is that it’s more disease prone. Finally, we head from another farmer that our staple summer green curly lettuce is also incredibly cold tolerant. We’ll see how cold tolerant it is this year but I’m expecting it to be about as good as our lettuce mix.

Kale

We’re growing both red and green kale. We’ve found that adult size kale has about the same cold tolerance as our lettuce mix. The big problem is that the kale plants are fairly tall and far away from the ground which is our main heat source in the winter. The further up into the air the kale is the more likely it is to be damaged by cold temperatures. We hope to have kale available into December.

Spinach

Spinach is our workhorse winter crop capable of withstanding temperatures as low as minus 10 degrees. Spinach does this really cool thing during cold snaps where it drains the water from it’s leaves to protect itself from the cold. It looks like it’s wilted and dead but as soon as it warms up again the spinach looks good as new. Most winters we are able to produce spinach all winter long.

Bok Choy

We found a new-to-us bok choy called “winter yellow heart” where the seed company claimed it could handle temperatures as low as 5* in an outdoor setting. We’re excited to see how it performs in a tunnel with row cover. If successful, we could have bok choy into January.

Scallions

We’re trialing a new variety called ever green hardy that is supposed to be the most cold tolerant scallions available. Our standard variety does over winter but usually gets unsaleable after it gets below about 15*.

Radish & Hakurei Turnips

Both radish and hakurei turnips can handle some cold but usually once it gets below about 15* they suffer enough damage that they’re unsaleable. We’ll probably have turnips and radish into early December.

Mizuna & Tat Soi

Similar to radish and lettuce mix both Mizuna and Tat Soi can handle the cold to a point. Once mature they will be part of our winter mesclun mix. Look for that at the end of November and early December.

We’ve heard that we’ll be in a La Nina weather pattern for this winter which means colder and wetter than usual. The cold is a bit concerning: if we get too cold too fast or have a polar vortex early it could damage many of these crops before we’re able to sell them. The extra precipitation is good though. The snow can help to insulate our tunnels and help our crops to survive the coldest temperatures.

We really enjoy pushing the boundaries on what’s possible in the winter in southern Minnesota. We learn a lot each winter and it is SO satisfying to bring fresh greens to CSA shares and winter farmers markets long after the first snow flies! We will continue to push boundaries and find innovative ways to bring fresh produce to market season after season.