Greenhouse kale: row cover makes a big difference!

This winter, my greenhouse was filled almost entirely with kale. The leaves held up very well to the cold, though by January, the stems were pretty knackered from the alternate thawing and freezing. In min-January, I harvested all the remaining leaves from all the plants (leaving only a couple tiny leaves in the center of the rosette on some of the plants) and figured kale production would shut down for a couple months. That’s pretty much what happened, but look at these pictures. You might want to click on them to view bigger versions – the dark purple kale doesn’t show up very well on the black plastic mulch.

This is a picture of the end of the bed that had no protection except the greenhouse itself. Keep in mind, this is a very small greenhouse in a very cold microclimate, and we had almost no sun at all this winter. We had two sunny days in a row last week, and I think that’s the first time that’s happened since November. *sigh* So temps in the greenhouse were under freezing every night, sometimes as low as 5 degrees this winter. (Though the soil did not freeze much at all – small patches for a few days at a time, not frozen solid like last year. Yay, raised beds!)
Kale w/o row cover through the winter
You can see these stalks look almost dead. They aren’t – there are tiny leaves starting to sprout in the crooks of the the old leaf scars on the stems – but it’s clear these plants need several more weeks before I can think about harvesting again. The couple leaves of the dino kale in the foreground were there all winter but don’t seem to be helping the plant recover much.

Now contrast this kale. Look closely – you might need to zoom in – but you can see the leaves are about the size of my palm and growing fast. These plants are the same variety as the others, but they had some row cover draped over that PVC frame. Quite amazing what a difference it makes!
Kale that had row cover through the winter
I love the color of this kale. The new leaves have started out as the deepest, richest purple I’ve ever seen on a plant leaf. As they get bigger (and perhaps as they get more sun,) they get some green in the center of the leaf. They are so sweet, they almost don’t taste like kale. Not a bonus, in my book, but interesting nonetheless.

The plants that survive the winter and the varying heat of spring win the lottery: I’ll let them go to seed and harvest my first brassica seed to save for next year!



  1. Diana Dyer said,

    February 24, 2010 at 6:18 pm

    I love collecting my own kale seeds, too, from those hardy specimens who made it through a Michigan winter! Have fun collecting next summer. They do pop all over the place when the pods are really dry, which is how I ended up with a kale hedge in addition to seeds to actually plant where I want to plant them!

  2. March 2, 2010 at 7:14 am

    Thanks for sharing this. It was indeed interesting to see how a row cover can make a difference. We had a pretty bad winter, although some of my plants survived the cold, a lot didn’t. Raised beds and row covers, that’s something I will keep in mind next winter. Goodluck on your kale!

  3. Tilly said,

    May 17, 2015 at 6:44 pm

    Hi, I’m looking at growing Kale in my greenhouse this winter, can you tell me which type of Kale you are growing ? Thank you in advance

    • Emily said,

      May 21, 2015 at 1:27 pm

      The curly types tend to overwinter well – Winterbor, Redbor, Vates. The Siberians aren’t bad, either. I’d try it with all of your favorites and see how they do!

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