The use of greenhouses dates back centuries. Typically found on estates on a grande scale, they were historically reserved for those of wealth and privilege. The first known greenhouses were recorded in Rome. Today, they can be found on a small scale in a humble backyard, on school campuses, and large-scale commercial facilities. The size, investment, and purpose may vary, but the benefits are universal.
Having a greenhouse allows gardeners to extend their growing season. Because it is temperature controlled, you can grow virtually year round from your cool weather crops like lettuce, cabbage, kale, and cauliflower to heat lovers like tomatoes, cucumber, and squash. A greenhouse is also a safe haven for your plants to hibernate if you will, or more accurately called overwintering. Bring them in for shelter from the harsh winter and bring them back out to enjoy again the following spring. Do you love the lush, vibrant plants of more tropical regions? Bring the tropics home and grow non-native plants in a greenhouse.
There are three primary elements that make up a greenhouse: a frame, floor, and cover. Historically, greenhouses were made of glass. Plastic is very common now and we have a University of Kentucky Professor to thank for that. Many of us have probably seen the white, heavy plastic clad greenhouses during a drive through the country. I was tickled to learn during my research for this article that the credit for that creation goes to Dr. Emery M. Emmert. Dr. Emmert is regarded as the “father” of the plastic greenhouse. He spent thirty-four years at U.K. teaching horticulture beginning in 1928. He studied and invented plastic greenhouses during 1948-1955. Just as glass does, covering a greenhouse frame with plastic draws on the sun’s energy to heat the enclosure. Since the heat is trapped, proper ventilation is important. Think of it as a sheltered microclimate where you can control temperature, humidity, soil moisture and drainage, and more. A greenhouse allows you to take back control from Mother Nature.
Dr. Emmert was on the forefront of greenhouse technology up until his passing in 1962. Today, the science and technology behind greenhouses is growing. Growers have access to technology that can track almost any environmental factor that they want to study. Daniel Bustle is an Agriculture Instructor and the FFA Advisor at Locust Trace Agriscience Center in Lexington. “I can track temperature changes, air movement, humidity, watering frequency, and external weather data. There are apps for phones that assist with chemical measurements, and apps that help track and identify pests that improve IPM (Integrated Pest Management),” Bustle said. Bustle’s students take what they learn inside a traditional classroom and put it into practice in the school’s state of the art greenhouses. “They get the opportunity to see a plant from start to finish,” he said. Even with all of the technological support, in its purest form, growing in a greenhouse is still a very organic process for students to participate in. “I think it’s an amazing opportunity for us. Most of our generation is absorbed in technology. They eat, sleep, and breathe around technology. It’s kind of unsettling to know that most of my generation doesn’t know how to grow and nurture a plant,” said Hannah Braden who is a senior at Locust Trace.
In addition to learning the science behind plants, there is a business component for students at Locust Trace. The students sell the plants they grow out of the greenhouse. The seasonal sales are open to the general public. In the fall you will find mums. Winter is plentiful with poinsettias. The spring is a bounty of herbs, vegetables, hanging baskets, flats of flowers, and ferns. “The money that is made goes back to the greenhouse account to provide continued opportunities for next year’s class,” Bustle said. Home growers with a greenhouse can cash in too. When you are growing from seed, chances are you will have more than your fair share of plants and vegetables. What better opportunity to share with friends, family, and neighbors, or sell them. Everyone wins. You can make a little money to recoup what you spend on seeds and your friends can save from paying the high price of retail at a nursery.
Those are the benefits. But before you reap them, there is the initial investment. A quick search of greenhouses online can leave you with sticker shock. Several hundred dollars for something simple up to several thousand for a showy, top of the line glass enclosed structure. While greenhouses can be very expensive, they don’t have to be. It can be costly if someone wants a greenhouse with all the bells and whistles. A greenhouse can be built to the size that you want. If you want something in your back yard or on your farm, you can determine how much space you want to dedicate for a greenhouse. While I have visions of a gorgeous greenhouse some day, realistically I know I will need to win the lottery to make that dream a reality. That doesn’t mean a greenhouse is out of my reach or yours. From a simple cold frame to a fully automated greenhouse that practically does all the work for you, there is something for everyone. It’s important to know what is available and compare it to your needs and the time you have to devote to it. Again, we have U.K’s Dr. Emery Emmert to thank for the choices we have today to extend the growing season.
Cold frame. This is the most cost effective option. A cold frame can cost as little as $30 for a small one. Think of this as a box like structure that sits low to the ground and acts as a mini greenhouse. This is the perfect option for the gardener who simply wants to get a jump start on the growing season and start his/her seeds, or who wants a safe place to insulate their plants during the winter.
Low tunnels. Also called “quick hoops”, low tunnels are made of wire or PVC hoops covered with clear plastic or row covers. They are typically about a foot and a half tall. They cover the crops, which are in the ground for up to a month before the covers are removed for the spring growing season. The covers may be replaced in the fall to extend that growing season a little longer. They are often used in conjunction with black plastic mulch and drip irrigation. Low tunnels are also good to protect crops from the wind. A low tunnel is cost effective. They can be built for $0.25 to $0.50 per square foot.
High tunnels. The high tunnel is the greenhouse of Dr. Emmert’s day. It may also be called a “hoophouse.” These structures are made of a curved or “hooped” frame tall enough to walk through. Sources for framing include metal pipe, PVC pipe, or wood. The frame is covered with greenhouse grade polyethylene plastic. What they may lack in a high tech temperature controlled greenhouse, these more than make up with their ability to adequately control temperatures, provide soil warming, and protect plants from wind and rain in the simplest form. The cost for a high tunnel may range from $1.00 to $2.50 per square foot.
As the options are weighed, growers may realize a conventional greenhouse may not even be needed. Instead, a simpler structure may be both economically and realistically a better fit. It boils down to needs, cost, and ambition. With that in mind this may be a great DIY project. Before you build, do your homework.
Builders beware. Don’t put your cold frame, hoop house or greenhouse just anywhere. Optimal placement is crucial. The structure needs to receive plenty of sunlight, preferably southeasterly sun. You can supplement with artificial lighting, but remember, that costs more money. Your structure should be free and clear of obstructions like tree limbs that could fall and damage your greenhouse. Consider flooring that allows for good drainage like pea gravel. And anchor it. You don’t want it to go up, up, and away with a heavy wind.
Back at Locust Trace Agriscience Farm, the value of having a greenhouse isn’t lost on students. “It’s an experience and opportunity you can’t get just anywhere,” said Keaton Smith who is a senior. “The greenhouse is a tool that makes real world learning happen. Students are able to do more than talk about theories, they have the opportunity to apply and test theories,” Bustle said. “This also gives students the opportunity to learn a skill that can sustain them for the rest of their life,” he said.
Aside from nutritional sustenance and beautifying one’s surroundings with homegrown plants and flowers, there are the spiritual and emotional benefits. Tamuz Babatunde is a junior at Locust Trace and says it’s nice to be out and one with nature. “It’s almost like I’m living along with them, helping them like a family,” Babatunde said. Hannah Braden agrees. She says retreating to a greenhouse can be relaxing and calming. “When I am in a greenhouse it is like an escape form reality. There’s innocent living things all around you and it’s amazing,” she said.
If you are looking for greater control of the growing process, a greenhouse may be worth the time and investment. There are several great resources out there to help. The U.S. Department of Agriculture has help at your fingertips with their Virtual Grower. The online tool can help you with everything from greenhouse design, choosing the right crops, growth schedules, real-time predictions of energy use, and more. See how the at ars.usda.gov.
The Center for Crop Diversification at the University of Kentucky will host a High Tunnel webinar Series on Tuesday evenings through the month of March. The free webinars are hosted from 6:30-7:45pm. Topics include crop and equipment options, insect, weed and disease control, and hear from local growers about their successes. For more information visit uky.edu/Ag/CCD. Learning about greenhouses is just like everything else I have found when it comes to gardening. It is ripe with opportunities to collaborate and learn from others with a shared passion.