Keeping a greenhouse warm enough to propagate plants in months as cold as January and February can cost a lot of money, but Roberto G. Lopez, a Purdue University professor and Extension specialist, has a few simple tips that can help bring energy costs down.
Start with checking you greenhouses for small leaks, he says. It can make a huge difference in heating costs.
“There are a lot of places where you don’t realize you’re losing a lot of heat through tiny holes around vents or in glazing material, or people not shutting doors correctly,” Lopez says. “Just going into our greenhouses here at Purdue, there are a lot of holes we have found.”
Energy prices have steadily risen in recent years, but plant prices have not always kept pace. Lopez says the cost of natural gas more than doubled in the last decade, while the wholesale price of a poinsettia, for example, increased from $4.21 to $4.61–only about 10 percent.
“What we have seen over the past few years is that some growers shut down over the winter to save money on heating costs,” he says. “There’s also a temptation to lower their greenhouse temperatures.”
Instead of shutting down, he suggests growers use energy curtains that serve dual purposes. The curtains can trap heat generated during the day by being drawn over the plants like a ceiling when the sun goes down. They also are useful in the summer to provide shade when it gets too hot.
If energy curtains aren’t in your budget, another good idea is to insulate the north side of a greenhouse. Lopez says it’s the side that gets the least amount of light. So insulating it won’t cost much in terms of sunlight, but could save money on heating.
Growers also could look for varieties that grow at cooler temperatures. Lopez says that could allow growers to lower temperatures in their greenhouses without affecting plant development.
Other options include finding other growers in the area to buy fuel collectively, as well as searching for grant funding through the U.S. Department of Agriculture to purchase an energy-efficient heating system.
“It’s a great tool to have,” Lopez says. “It saves a tremendous amount of energy.”