When it comes to gardening in a greenhouse, I can honestly say the best times I ever had was after I shut down the commercial nursery and filled a 1500 square foot solar greenhouse with tender garden plants. I started growing a wide range of collector annual plants I’d winter over and built a 10X50 foot “garden” out of old concrete blocks (filled it with soilless mix) and started growing vegetables and plants for our own family consumption and use. I had a rather large collection of unusual but tender plants that survived quite nicely out there just by keeping the frost out of the greenhouse and with it being a solar one – it wasn’t all the expensive to keep heaters operating. And I learned a heck of a lot doing this.
The important things to consider.
There are a lot of folks who think that just because you stop a plant from freezing by putting it into a hobby greenhouse, it will keep growing through the winter.
I know more than one gardener who wanted to grow tomatoes year-round (it can be done) and thought a greenhouse would do the trick. Here’s the trick.
In low light months (November through February) there simply isn’t enough light outside to keep plants growing and fruiting. They’ll all slow down no matter how much heat you toss at them. If you want greenhouse vegetables to keep on growing strongly, you have to give them adequate light levels.
Doug’s solar greenhouse in spring circa 1979
The problem with this of course is that the harvest amounts aren’t going to be very high (you can never get enough light onto these high-light need plants) and it becomes uneconomical to grow them.
So while you can’t economically grow greenhouse tomatoes, you can grow a lot of leafy vegetables such as spinach, lettuce etc and you’ll never want for salad fixings.
I had a big bed in the middle of the greenhouse (2 cement blocks high filled with an soilless mix – Promix) in which I grew all kinds of vegetables that thrived in lower light conditions (mostly leaf vegetables)
The major issue with my greenhouse growing was that I didn’t want to have to run the greenhouses in the summer time – the energy costs to keep them cool are substantial. So I tended to grow everything in containers in order to move the plants out of the greenhouses after frost.
I used clay pots for the most part and found the plants did very well in them.
The serious advantage to gardening in a greenhouse is that you can propagate darn near all your plants so your costs are reduced to near zero.
This is particularly true for those of us who collected “different” annuals and kept them over from year to year.
Simple propagation systems worked well to produce scads of cuttings for container gardening and great garden flowers.
You really want to have a source of water so you don’t have to bucket it to your plants. I have to tell you that carrying a bucket gets really old,
I ran 3/4 inch plastic hose underground to the greenhouses and it worked quite nicely.
I mentioned this above but too many people don’t calculate exactly how much air they have to move out of the greenhouse in the heat of the
Here’s how to do that
Remember that plants stop growing (photosynthesis stops) around a leaf temperature of 83F. Temperatures over that (as in a hot greenhouse) are merely stunting your plants.
I dealt with this in other posts but generally, a decent sized greenhouse is fairly inexpensive to build out of 2×4’s.
The place you don’t want to skimp is in the plastic. There’s nothing like watching your plastic get too brittle in winter and shatter into a gabillion bits in a high wind – knowing all that work you did with the plants is now gone. (been there, done that)
Doug’s Summary Thoughts
I’m a big fan of gardening in a greenhouse – but do take a few minutes to consider the facilities and what you can grow in them before you rush out.
But then rush out. 🙂
Different styles and prices for a wide variety of greenhouses and vendors
You can read other articles on greenhouse gardening here