A greenhouse can change a homestead or small farm. No doubt about it, it can stretch your growing season by months, on both ends, and if heated, and with grow lights, you can produce food year round. But there is one downside:
The high cost of heating it in colder months, especially if you live farther North.
Our back story to how I spent way too much last winter was a long lesson to get into my head. Our first years on Never Free, I had cheap “disposable” pop up greenhouses (think $100 or less, a metal and plastic frame with plastic cover). While they worked well enough to keep plants wintered over and mostly alive, they are not truly a greenhouse. I only got about a solid year out of them. Even my favorite, below, the cover rotted as the second winter hammered it. (Having said all this, if it is all you can budget, it works well for what it is. You can’t do everything, but you can at least get plants started in early spring…)
In 2016 we bought a Sunglo greenhouse and built it. It was a large undertaking, but well worth it.
In the winter of 2016-17 I went crazy in it. I was growing kale and lettuce in late fall and early winter. We had strawberries all winter. My many citrus plants. The greenhouse hummed along. As winter turned into spring, I started the tomatoes, herbs, and strawberry seeds. Finally, by May my greenhouse was empty and it was all in the ground growing, or sold as extras.
In the winter Kirk realized we were using too much energy. We turned down the heat to save money. We only had it kick on then at around 45*. Well, even that was expensive. Even at 40* it was brutal. The harsh truth is, even if you have a well insulated floor, as our does, and double layer walls, greenhouses are going to be drafty. The vents may close, but they are not insulated, this is where they leak. It is a very bad use of energy. Even with those final months cutting back on the heat, our electricity bill was outrageous. Any profits we made in growing food was burnt up by the cost of the energy.
So why didn’t we use solar energy, like we do year-round to run the fans? We are too far North in the Pacific Northwest. In late January we have barely 9 hours daylight. Our panels can run the fans in winter, but the energy hog heater it cannot power. The sun is too weak, too low, and too often it is hidden behind the clouds. If we lived farther South it might be different. The other issue is the heater that came with our greenhouse is nothing more than an old school space heater. It is an energy hog. It’s simply takes too much energy to power it, and would tax our already taxed solar system.
So for the 2017-18 winter we were much more conservative. I unplugged the heater, and instead used a roll of frost fabric to cover the citrus trees, taking a hack I used in the pop-up greenhouses. I dragged the citrus pots away from the walls (less foot space, but oh well, the plants stayed warmer), stuck in each pot a wooden stake, and draped the fabric over the plants using the stake to keep it up, holding the fabric on with binder clips. Frost fabric can provide about 5 to 10* of protection. It doesn’t often get deep freezes here, so plants will survive if protected. Our aloe vera plants we put on a shelf up higher, and did similar.
How did it fare? I was concerned when we had a week of Arctic freezing, but decided I would just trust in the fabric. I didn’t plug in the heater, no matter how much I wanted. And then a week of snow came as well. And I waited.
What I found was due to our excellent insulation, there wasn’t condensation this year in the greenhouse, with no heat on. During the day it often reached the 70’s and 80’s inside. I love working in it on a cold day, it’s very toasty inside. On hot days, the fans kick on, using solar power.
Recently I checked on the plants, to see if they needed watering, as we had many sunny days. While watering I was amazed at how healthy the aloe vera plants were. Thick, sturdy and no blackening. If anything, they are thriving under the frost fabric. (And as you can see, we are starting to ramp up for the coming spring production.)
Another thing: last spring I noticed some of our citrus plants had been too close to the grow lights. It led to the trees growing rapidly, and left them weakened overall. Most of the plants I had to cut back severely before fall came. Lesson learned. Citrus doesn’t like grow lights.
The other bonus is at night it got cold enough to finally kill all the fungus gnats that had gotten into the greenhouse. We had a batch of soil that was contaminated last winter, and I constantly battled the (mostly harmless) but freakishly annoying bugs. Like mosquitoes, they go right for your breathing and you end up having them try to fly into your mouth or nose. A good freeze is always good for greenhouses…..
So the lesson? Watch your energy consumption. You will have a hard time justifying heating your greenhouse after a few month’s of bills. Use passive methods to keep plants alive. And treat winter as a time for the greenhouse, just like the fields, as resting time, if you can. And invest into a roll of frost fabric asap.
As a side note: We are still looking for a heater that isn’t an energy hog, that can run on solar.