Here’s where we start with greenhouse basics and giving you all the information you’re going to need to make your decisions about your own greenhouse growing.
What I’m going to tell you in these pages will not be the same thing as you might have heard before in garden magazines or sales literature.
You see, I want you to succeed at this, and the only way you’ll do it is if you make the right decisions going into the process. If you have the proper expectations of what a greenhouse can and can’t do for you.
So let’s dive right in with a few questions I regularly get.
Can I grow vegetables all winter long?
Well, it depends. There are three factors that influence your ability to grow vegetables.
- The first decision is what kind of vegetables you want to grow. Plants like tomatoes require very high light levels and winter is a time for shorter days and low light levels. But plants such as spinach or Chinese cabbage don’t require as much light. So if your goal is to have fresh tomatoes, then your choices are going to be different than if you want Chinese cabbage.
- The second is heat. Tomatoes want 65F nights or the pollen goes sterile and you won’t get a crop. But spinach grows/survives quite cool temperatures. I always ask folks how much money they want to throw at the greenhouse – particularly compared to buying good produce.
- The third is the light level in the greenhouse. Wait! Didn’t you already say that? Yes for the light level needed by the plants but no for the light level in the greenhouse itself. Let me explain. My solar greenhouse (1500 square foot) was very energy efficient but it cut off a good 40% of the light available because it had an opaque/insulated north roof. So I could afford to heat it but there wasn’t really enough sunlight for tomatoes to grow properly.
Here’s the Real Story They Don’t Want You To Know.
When light levels go down in the winter (shorter days) then vegetables such as tomatoes stop growing. And the pollen stops being produced. So you don’t have new tomatoes growing.
- Can you light them? Yes.
- Can you add enough heat to keep them growing? Yes.
- Can you afford that heat?
A low light level greenhouse such as this simply won’t produce crops requiring high light levels
But how rich are you? Frankly, you can buy the most expensive organic tomato in the fanciest store much cheaper than you can grow it yourself in your own greenhouse.
Vegetables such as kale and Chinese cabbage can be harvested all winter long if the greenhouse doesn’t freeze solid (most do because of the design) then you can harvest all season long. But even these tough plants don’t “grow” when light levels go down.
The hard reality in greenhouse basics is that after one attempt to heat and keep plants alive in a greenhouse in a cold climate, most home gardeners abandon the attempt and go back to overwintering plants indoors, buying from a store and saving money in the meantime.
There is also a climate-region variable. If you live in an area where the temperatures are relatively mild, you’ll be able to do things that my -25 winter won’t allow me to do.
So it depends.
There are some gardeners who don’t mind tossing a lot of money in heating costs at a backyard greeenhouse and consider it a “hobby” cost. Just know this going into the “hobby” and you’ll be fine.
There are many gardeners who use a hobby greenhouse as a fine looking cold frame or a tool shed. 🙂 No heat, no lighting and used for growing perennials or sheltering transplants in the spring.
So there is a way to really use a greenhouse?
Definitely but you have to pick your crops, your designs and your objectives really carefully so they’re consistent with your garden activities.
What about solar greenhouses?
There are some advantages to solar greenhouses and other energy efficient systems such as grow-tunnels and cold frames that I’m going to show you and explain to you.
But again, what they don’t tell you is that with a solar greenhouse, light levels go down even more than with regular greenhouses and growing slows right down as a result. I can say this with authority because my 1500 square foot propagation greenhouse was a full Brace Solar Design – half buried in the ground and quite energy efficient but with less light than the traditional hoop greenhouses.
Are You Saying I Shouldn’t Have a Greenhouse?
I’m saying you should understand exactly what one can and can’t do for you and what you want it to do. That’s what these greenhouse pages are going to set you up to understand.
Will You Have a Greenhouse in Your Garden?
I start my seeds indoors on racks in a growing area, well lit by artificial light. It’s cheaper to heat and light my basement than it is to heat a greenhouse.
I will be building and demonstrating the kinds of inexpensive crop shelters I’m going to use in growing my plants. Stay tuned.
But no, I won’t have a greenhouse I have to heat, it is far less expensive to install proper indoor plant lights than it is to heat a greenhouse. Not as sexy but more efficient.
And while I love messing about in a greenhouse, on our windy island the heat loss is amazing (even on houses) so a greenhouse is just too expensive for what I’d use it for.