Article: Greenhouse Lessons & Resilient Winter Greens

February 1, 2017

It was -21C last night and I forgot about the greens in the greenhouse again. In the early afternoon, I went to see the extent of the damage, and was very pleasantly surprised to find most of the plants looking green and perky :)

This is the first winter we've had the bed full of greens overwintering in the greenhouse. (In summer 2015, the bed was occupied by unhappy eggplant plants and a few greens, so last winter we didn't have much to experiment with.) We had severe drought and heat waves in the summer of 2016, which was very hard on our gardens (read more about it here). In early August, I started kale, arugula, mizuna, spinach and tatsoi and lettuce seeds in pots; in mid-August I started more kale, arugula and spinach seeds, because I had such low germination from the heat. I think I transplanted all the seedlings into the greenhouse bed in early September. In the meantime, I'd let the Red Russian kale, Siberian kale and arugula plants from earlier in the summer go to seed; as I was very late harvesting the seeds, they self-seeded all over the greenhouse. This turned out to be a huge gift.

In December, I had covered the whole bed with a thin floating row-cover. When -24C and -28C temperatures were forecasted mid-month, I covered the bed with a light blanket. Once it warmed up a bit a few days later, I removed the blanket and promptly forgot about the plants. In early January, we got -24C. When I thought to harvest over a week later, the bed looked like a disaster; I did manage to harvest a large bowl of greens, however, a lot of leaves, especially some of the bigger ones, had died from the cold.

Last week was slightly below freezing; as we were also nearing the end of January, there were more hours of sunlight and the sun angle was slightly higher too. The soil was dry inside the greenhouse, except immediately near the sides where the snow seeped in a little from outside. The plants looked very floppy and I wondered if most of them were dead. And just in case, I removed the row cover to give them more sun and watered them for the first time in several weeks. As it turned out, they were still alive and just thirsty! They perked up again and had a few days to recover, before they got hit with -21C last night. This time, I'd even forgotten the row cover and amazingly most of them survived; I'm guessing that after -24C without the blanket, the ones that hung on were fine without the row cover. I harvested a beautiful bowl of greens.

So, you're probably wondering: who survived? With the lack of sunlight, they barely grow; the surviving plants are small and putting out little green leaves at the base of the plant. The self-seeded Red Russian and Siberian kales are doing the best; they've succeeded from sheer volume and seem well-suited to the cold. Most of the tatsoi plants look perky and seem not too bothered by the cold; however there are far fewer of them, as I had started and transplanted them. A few arugula, mizuna and lettuce plants have survived too, so the mix made a lovely salad tonight.

We've found Eliot Coleman's books, “The Winter Harvest Handbook” and “Four-Season Harvest”, to be very helpful and inspirational. The following are the key premises that we took from these books. In this region, we get the same amount of sunlight as Southern France (Ottawa is at the same latitude as central-Southern France between Lyon and Marseille). It's the wind that dessicates and kills plants. Some annual veggies can survive cold temperatures if protected; two layers of protection (eg. plastic sheet over a low hoop, inside a greenhouse) is optimal, to buffer against the wind and cold, and to allow enough sunlight to enter. The plants hardly grow at all between November and February due to lack of light, and they don't need much watering; the point is to simply keep them alive. I recommend checking out Coleman's books for a lot more details about the types of plants and his greenhouse set up.

Outside our greenhouse in early December, with neither row-cover nor blanket and after about six inches of snow, the chard, kale, turnips and alliums (garlic family) were still well; the celery, oregano and feverfew were still green. The snow actually provides an insulating layer to protect the plants. Our friend Joanna takes bags of leaves on leaf-collection day and puts the full bags on top of their carrot, beet and turnip plants in the ground, so they can harvest directly from the garden in the winter.

None of this is rocket science. It just takes some observation, some trial and error, a bit of work, and a lot of careful attention to the plants and the weather. And it doesn't have to be expensive.

The first mini hoop house we built in 2011 cost about $30 with five six-foot PVC tubes and clear plastic from Home Hardware. It was wonderfully warm in there in March. However, the main drawbacks were that we had to crawl inside to water the plants (which is awkward with a full watering can), and since it wasn't a permanent structure, it wasn't very secure in big storms.

We built our current greenhouse adapted from a design by TexasPrepper2 on youtube (; I recommend watching the video. The main material we had to look for were “cattle panels”, which have to be strong enough to take some snow load and flexible enough to form the arch of the greenhouse. We bought two of them at TSC Store; they sell for $69.99 each. If we'd used recycled lumber and a non-UV-resistant plastic (the kind they use to wrap houses), the whole greenhouse could have cost around $200. Instead, we decided to invest in cedar lumber (which is rot-resistant) and greenhouse plastic (which is UV-resistant), so the greenhouse would last longer. We ordered the plastic from Growers Requisites (, which had a variety of widths to choose from and would cut it to the desired length; our order including shipping was just under $80, and we had plenty of plastic leftover. So our greenhouse cost around $350 to $400.

Admittedly, we do have greenhouse envy when we visit some of our friends' fancier home-scale greenhouses. I love Eric Toensmeier, Jonathan Bates and their families' greenhouse (read about it in “Paradise Lot” or tour their garden), which has an insulated North wall, a DYI aquaponics system and vermicompost under the floor boards of the paths; of course, I'm envious of the interesting hardy perennial greens they have, though they live in Massachusetts, which is a bit warmer than here. Titia Posthuma, a biodynamic farmer in our area, has a gorgeous attached 15 foot square greenhouse made of metal and glass, open to the Earth, and wedged in between a slab of bedrock and her handmade home; it seems like the ideal place to have breakfast and start seeds in February. And of course, there are the cold climate Earthships, which look like paradise tucked into a hillside (Sébastien has visited a local one, though I've only visited one in Haiti). I adore Kaia's urban attached greenhouse made with old windows and found materials, which passively draws heat from the old, not-so-well-insulated brick house; hers is a very site-specific design, and she eats cherry tomatoes in a tank top in the heart of an Ottawa winter, so it's definitely my local favourite.
greenhouse, aquaponics, Eric Toensmeier, Jonathan Bates
If you love to garden and eat, I hope this inspires you to experiment more! For me, there's nothing like a few bites of fresh food straight from the garden, especially when everything is covered in a foot of snow. Thank goodness, we are passed Imbolc; this cross-quarter day is in between winter solstice and spring equinox, so the promise of green gardens and the call of seeds beckon us from the horizon.


February 23, 2017

If only for the joy of feeling the sun on my shoulders in February, having even the simplest of greenhouses seems to be SO worth it!

On Monday, we had sun and clear blue skies -- it was +3C outside and 21C in the greenhouse!  I've enjoyed several one to two hour sessions in the greenhouse in the last few days.  I've been happily shelling beans (that I meant to take care of earlier in the winter), cleaning up the greens that got decimated by the cold and catching up on reading.  I also discovered that the wifi reaches out here, so I can catch up on emails too.  Even with our $30 hoop house, I used to lie out there and sun bathe in March... 



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