Welp, it’s officially cold and all of my beautiful annuals have bitten the dust. I did rescue one lovely apricot hibiscus and a few adorable succulents, which are now adorning my living room.
The only color left outside seems to be coming from fall leaves and seasonal decorations. While fall colors are wonderful, I find myself already missing my lively plants.
At times like these, my mind starts drifting to thoughts of backyard greenhouses. While I haven’t quite gotten up the nerve and/or energy to make one, I have done a decent amount of research into the magical world of greenhouses and thought I’d share in the bounty of my knowledge.
First off, let’s make something clear: Greenhouses can be as simple or as complex as you want them to be. You can go all-out with custom building materials, watering systems, heating systems, vents, the whole nine yards.
You can also stop by Habitat for Humanity ReStore (one of my favorite stores for DIY projects) and pick up old windows, glass doors, spare lumber, etc., and whip something up over the weekend. I’m going to be talking about simpler, more cost-efficient methods for building and optimizing greenhouses, but know that you can go as big and as fancy as you’d like.
If you’re going to build a greenhouse, your No. 1 supply is whatever you’d like to use for glazing (the stuff that lets the light in.) Glass or plastic sheeting are the most common materials, with plastic being an excellent option if you’re on a budget. I personally prefer the look of glass, but it will cost more, unless you get an excellent deal on used windows or sheet glass.
The downside to these materials is that they are almost as good at letting heat out as they are at letting it in. This is fine during the day, since the amount of heat pouring in is more than enough to combat heat loss.
The issue arises when night rolls around. Insulation techniques like weather stripping and horticultural Bubble Wrap can help, as can building your greenhouse so that it’s broadest side is south-facing. But ultimately, come nighttime, something must be done to combat the cold.
Your other materials will be an important line of defense. Most basic greenhouses are made of wood, but materials like stone and concrete will retain more heat during the day, which will then seep back into the greenhouse overnight.
You know what else is amazing at retaining heat? Water. If you have room in your greenhouse for a barrel or two of water, they will soak up all of that delicious sunlight during the day and let it out low and slow during the night. Ain’t nature grand?
Unfortunately, water, concrete and insulation can’t help against the coldest nights in our region. That’s where heaters come in.
My favorite method is simply a solar-powered heater with a battery to store energy during the day. However, a basic space heater or stove can do the trick.
If your greenhouse is small enough, something as minor as a slow cooker full of water set to low can keep your plants happy. If you’ve insulated well and use water and light to your advantage, the heaters will only be necessary some of the time. They act more like a fail-safe, especially if you get one with a thermostat that will switch the heater off once you’ve reached about 50 degrees Fahrenheit.