I have to confess to having been hibernating until now. It’s been an odd winter here: first it was mild. Then it was cold. Then there was snow for a couple of weeks before it melted. Then it snowed again. And now it’s all gone. When it was cold, it was very cold. Temperatures dipped down to more than -10 degrees Celsius for days at a time. Then they would yoyo and jump into the positives. Not an especially typical winter here in Oslo and subsequently it’s been throwing everything into confusion including these red squirrels I saw the other day playing together outside.
As far as growing in my winter cold frame goes… it’s been an interesting experiment so far. I’ve relied heavily on weather forecasts to track the fluctuating temperatures and prepare my cold frame on a daily basis. On cold nights, I’d cover the frame, and on those super cold days I’d leave the covers on, sometimes for days on end.
When it snowed I cleared it off the top of the frame to primarily allow some light in. Ordinarily snow would provide natural insulation. Alas even with the brightest days the temperatures never really rose high enough and
the compost remained frozen so there was no real benefit to removing the covers.
Moisture collected on the underside of the glass and I’d wipe the glass down every morning. When it got very cold it would have frozen before I’d had a chance to do it so formed a thick later of ice.
The plants seemed to be coping until the prolonged high freezing temperatures hit and then subsequent thawing. From the excessive moisture build up that followed, there was damping off which seemed to result in irreparable damage.
Out of three containers, only the one with the Winter Purslane has survived significantly. This patch is just about hanging on!
Without a doubt I am disappointed not more plants survived but I really didn’t know what to expect from this experiment so I’m glad I tried it. I would definitely try growing winter vegetables again but with the following considerations in mind:
- Sow winter seed varieties much, much earlier so that the plants are more established and are stronger before the cold sets in.
- Try insulating with wool (rather than fleece) during very cold periods.
- Protect the most exposed areas of the cold frame (in my case, the front) by buffering it from the harshest winds/temperatures. It may not be a coincidence that the purslane, situated at the back of the frame, suffered the least.
- Slightly raise the containers off the ground (and insulate underneath) or submerge containers into the ground at least a few inches or more if it is practicable!
- Use an outdoor thermometer to monitor the internal temperature of the cold frame.
It would be tempting to use a thermostatically controlled heater/heating element inside the cold frame but I think I’d prefer to wait until it’s warmer rather than grow with artificial heat.
I’ve not yet figured out how to balance keeping the cold frame adequately ventilated to prevent the build up of condensation with maintaining adequate heat inside the cold frame on those colder days. Another cold spell is expected in the next few days. Time to brace the cold frame again and perhaps try to figure that conundrum out. Meanwhile, I’ll start looking through seed catalogues and dream up what I can plant this forthcoming spring.