From Seeding to Harvesting: A Winter Growing Journey


April 17, 2023

Research & Development Greenhouse Summary

Hello again! It’s Jennica here.

Last fall, we launched a research and development project, thanks to our new partners Planta Greenhouses! I want to share the progress and some of the things we have learned along the way.

It has been quite interesting trying to grow things in the deepest part of winter here in our zone 3 climate. The Planta Sungrow has been an excellent structure and has held up through the extreme winter conditions we have experienced in Alberta.

Seeding in November

As you may remember, we seeded several varieties of greens, broccoli, cauliflower, carrots, beets and garlic on November 10th. We installed supplemental lighting and used a small space heater to keep temps above freezing. The grow boxes were also covered with more of the reflective bubble wrap. This served us well, as it helped keep more heat around the seedlings and was able to maximize the light we had. 7 days later, we had seedling emergence which was very exciting! We were able to begin harvesting just in time for Christmas!


The harvesting is probably the most fun and rewarding part of winter sowing. We started harvesting arugula and spinach on Dec 21 and have been able to continue since then. We harvested about 4kg of greens, beets, radish and broccoli between December and March. Growing was notably slower during the very cold winter months, but we were steadily seeing growth with the added lights and warmer temperatures created in the greenhouse.

Maximizing Space

As time passed and our winter began to (slowly) turn into spring, we rearranged the interior a little bit to make more room for growing more plants. We used wire closet shelving and installed a nice wide length of this along the main brace at hip height in the greenhouse. This shelf is 20 inches wide and accommodates a standard-size grow tray perfectly. We also installed a 12-inch wide shelf above this to really make use of the space and sunlight that streams in. The grow bins were also rearranged and placed in a single row along the bottom edges of the greenhouse walls. The bottom bins were filled with water all winter long to add thermal mass to the north wall, but I have since removed most of the water in preparation for refilling with soil to plant into.

The stock tank remains in place and has been great for thermal mass and water access all winter. During winter we refilled it 2 or 3 times by adding about 20 gallons of hot water each time. Since temperatures have been rising and sunlight has become stronger the water needs of the plants have increased and as such, I have had to top up the tank 3 times this month!

Plant Sale

In mid-February, we received our order of herbs and plants for our plant sale fundraiser. Most of them came home with me after we had a cold snap and the heater decided to quit that night. We did have some frost damage and lost several tender herbs, but many have rebounded and are coming along fine again. The herb and salad planters along with the sweet peppers are all hanging out in the greenhouse now and seem to be quite happy there. Growth is happening and things are looking good! My shelving units are maxing out and we still have lots of plants to pot into bigger containers. I hope we will be able to sell off several planters in the coming days!

Greenhouse Temperatures

The smart monitors we have been using to track temperature and humidity have been working great all winter. They give us a warning when it is either too cold or too warm in there and we can add the recorded data to our tracking sheets for accurate data. Pretty cool!

The reflective bubble wrap was excellent at insulating and being easily adjustable. I did remove a strip from the north wall when we got our seedling shipment so they wouldn’t burn with the intensified light. I anticipate removing the end wall insulation as the season progresses.

We have added 3 windows in all at this time. Without them, the plants would be overheating and fried even though it is still -10 frequently outside. Our daytime temps often reach +25 inside and without the windows and automatic openers, the temps would double that. I will add another window or 2 as things continue to warm and we prepare for summer planting.

What an adventure it has been, growing through the winter. It has been an honor to be part of this team and push the limits on growing in Zone 3. I am excited to see what we can grow next winter!

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