Goldilocks wanted her porridge just right. Not too hot. Not too cold. And that is what I am aiming for with winter growing. The temptation to heat things up may sound like a great idea but can also lead to disease, condensation, more pest damage and weak growth. Too cold and the plants also suffer stress, leading to frost damage and earlier bolting. So where is the sweet spot? That is what I am experimenting with. And yes, I have been learning the hard way.
Today we will investigate one bed, as it looked so beautiful at dawn, covered with snow and emitting a pink light.
This is a pre-fab tunnel from Outsunny. I needed something low to allow sunshine access to the tunnel behind (though we have had so little this winter!). It is not particularly strong but with a few posts under the peak of the frame for support and with covers on to prevent the plastic cover from caving in under the weight of the snow, it works great. It also vents well with windows at the end and 2 zip doors accessed even with snow.
After a few years of winter growing in my hat, I do not bother with internal thermometers anymore but I decided that was wise in this bed after burning the first batch of plants with C7 incandescent holiday lights. In a higher tunnel that would not have been an issue. Barbaqued broccoli leaves anyone?
Generally I use smaller lights in my really low tunnels and should have here. I should also have planted lower crops. What I have installed now on an extension cord with 6 outlets are 2 Red Dot flood light holders with BR40 LED grow light bulbs that are currently keeping everything at around zero degrees. BR40 provides a more diffuse light than Par38, which I prefer.
Warmer may promote disease, mould and weak growth. Much colder will not please the recently planted lettuce. When it gets colder this week (-10 to -25 Celsius), I will either swap one of the light bulbs for a 100 Watt incandescent light bulb or cover more. A 150 watt bulb may burn things in such close proximity. I use halogen in my higher tunnels but it would burn the plants here. To reduce plant stress before a cold snap and to keep the leaves off the ground for disease prevention, I am experimenting with planting the seedlings right in the pots, buried an inch or 2. I will let you know how these poor plants, cast outside from under the grow lights, manage next week. Before planting out, I dug pre-fermented Bokashi kitchen waste about a foot or two under the ground to heat things up a bit and provide food for the red wigglers, who migrate from the nearby in-ground composters. Bokashi does not attract rodents. My family hates the smell just as much.
Bring on the cold. We need it and I am ready (I think)!