This spring has been cold and wet. We’re a few days away from May and it is still cold and wet. Fearing a year with wimpy tomato production (again), I took some drastic measures. I created a “hot” grow bed in my greenhouse. You’d think the greenhouse alone would be enough to warm up the beds. It helps, but without sun we’re not getting good tomato and cucumber soil temperatures yet.
Here, you can see another bed in the greenhouse that has not been made into a hot bed. There is a 14 degree temperature difference.
So, what is a hot bed? If you think of the seedling heat mats you use indoors, a hot bed is kind of like that, but on a larger scale. This hot bed uses heating coils and electricity. Here’s how I put it together.
First, I ordered soil heating cables. The cables were then attached to a piece of hardware cloth in order to keep them straight and evenly spaced in the soil. This cable is 36′ long, using 126 watts of power. The energy usage is definitely a consideration and I plan to unplug the coils as soon as the other beds in the greenhouse catch up temperature-wise. This is merely at attempt to jump-start the season given the terrible weather.
After getting the hardware cloth and heating cables in place, I installed the tomato cages, making sure they did not push into the heating cables. Then, I began planting the tomatoes. I have to admit, this was a pain to do with the tomato towers already in place.
The tomatoes have now been in the hot bed for a week and they are doing really well. I’m seeing lots of new growth and the color of the plants looks wonderful.
To offset the electrical usage, Derek and I have been discussing installing a solar panel on the greenhouse. This could be a good way for us to get started with solar, something that continues to be part of our long-term plan. I must acknowledge it does strike me as a bit funny to use a solar panel to create electricity to warm the soil in what is already a passive solar greenhouse, but gardening in the cool Pacific Northwest brings with it many challenges.
I fully understand that this kind of set up is not for everyone. Most gardeners do not have a greenhouse and those who do probably don’t have electricity available in their greenhouse. Even so, I wanted to give it a try and it will be a fun experiment to see if this set up makes any measurable difference in my tomato harvests this year.