I was in the eighth grade in College Station when my dad and I built a small greenhouse in our back yard. Having raised three children and being the grandfather of seven (one of them a mature eighth-grader herself), I now realize what a geeky kid I was to have been holed up in a 6-foot-by-20-foot greenhouse with hundreds of coleus plants and begonias. But there I was, and I was loving life just as if I were normal.
I came home one icy day in January in my youth to a lesson learned the hard way. Temperatures had dropped below freezing and the wind was blasting straight out of the north. I discovered that plain polyethylene plastic only lasts through one season. My greenhouse had blown in and my plants were all lost.
Undeterred, Dad and I built a new greenhouse on the south side of our garage. We cut a door through beside his workbench and he hooked into the gas line so I’d have a space heater. And we used Mylar, a durable new type of plastic covering I’d seen on the floriculture greenhouses at A&M. I was back in business.
As a side trip to my story, a man heavily involved in the landscaping industry in Brazos County now lives in the house I grew up in. We’re good friends, and he dropped me an email a couple of years ago to say that he had finally torn down that greenhouse in a major remodeling project. Some of my favorite childhood memories were while I was working with my plants, just a few feet away from my dad as he puttered at his workbench and listened to Aggie basketball on the radio.
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As I fast-forwarded to today to jot down these notes I realized that I’ve had a greenhouse (or access to one) from those first backyard lean-tos when I was 13, on through my college greenhouses at A&M, Ohio State and Colorado State, all the way to the used commercial greenhouse I’ve been enjoying for the past 36 years.
From all of that I’m going to give you pointers should you want to build or buy a greenhouse of your own to get your spring season off to an earlier start. These are facts and opinions earned from a lifelong love of gardening in greenhouses.
Considerations in building a greenhouse
▪ Check your city’s codes and applicable homeowner association restrictions and be sure your greenhouse will comply.
▪ Situate your greenhouse to get morning sun and possibly shade in the afternoon in the summer.
▪ Companies that sell shade fabrics to nurseries can fabricate a piece to cover your greenhouse. I leave a 62-percent shade fabric over my greenhouse year-round. Have yours bound and made with grommets, and have it cut 15 percent larger than necessary to allow for shrinkage.
▪ Buy as large a greenhouse as your space and budget will allow. Your greenhouse will never be big enough once you start getting large foliage plants.
▪ Evaporative coolers installed on the south or west sides of your greenhouse will help reduce the temperature in summer. They will also add moisture to the environment. Larger greenhouses would be better served by drip pads on the south side and exhaust fans on the north side.
▪ Benches should be made of aluminum or pressure-treated wood, and they should be 36 inches wide if you’re reaching from one side and 48 to 54 inches wide if you’re reaching from both sides.
▪ Since you must heat the entire greenhouse, don’t waste a lot of space with wide aisles. I have my benches 24 inches apart. Now that the my plants have grown larger, I can say that 28 inches might have been better.
▪ Put large washed gravel beneath the benches. It will reduce splashing, weeds and mud, and it will add to the humidity in the greenhouse. I do not have mist heads in my greenhouse except when I rig up a propagation bench for rooting cuttings.
▪ If the greenhouse’s overhead support is strong, install hooks or pipes from which you can hang baskets. Don’t overdo it, however, or you’ll risk pulling the framework of your greenhouse out of alignment. You’ll also be casting shade on the plants beneath.
▪ Vented natural gas heat is an excellent way to maintain warmth affordably, but you’ll need to have a generator available to run the blower in case of a power failure.
▪ The thermostat needs to be waterproof, preferably one made for use in greenhouses and barns. I can speak from experience — this is a real source of concern. One that a company installed in my greenhouse years ago failed due to condensation and I lost some valuable plants on a night that was barely below freezing. It shouldn’t have happened.
▪ Temperature alarms that will alert you should something go wrong will give you great piece of mind. And, as a follow-through with that planning, have a second source of emergency heat. Even if it’s nothing more than a camping kerosene heater to get you a few hours of warmth, it’s better than watching your plants freeze before your eyes.
Those are good starting thoughts on a greenhouse in your life. You can build one yourself or there are local companies that offer them. Plans and kits are available online. The next move is yours.