|Elizabeth D. Johnson|
It’s the time of year when leaves begin falling, the air becomes chilly, and we start stressing about our outdoor plants and vegetables. Not everyone may feel that they have the luxury of a greenhouse, but there are structures you can easily build to protect your plants from the winter air.
When building a greenhouse, local climatic data should be analyzed to determine maximum and minimum monthly temperatures, precipitation types and totals, heating and degree days, and sunny/cloudy days. This information is helpful in estimating energy cost and choosing the proper greenhouse design. Greenhouses will either be connected or disconnected and if building a simple one in your backyard, you will usually have a disconnected one. You could also build one off of a preexisting porch.
After you decide the design, you will want to figure out if you want a cold frame or hot bed. Cold frames are scaled-down, greenhouse-like structures that lack heating, and are used to extend the growing season. In the spring, they are typically used to start or harden-off seedlings. In the fall and winter, they are used for overwintering plant materials. A hotbed has essentially a cold frame design, but with some type of supplemental heat. Heat is generally controlled by a thermostat, and supplied with subsurface electric cables, hot water, or steam pipes. With both types of structures, care must be taken on sunny days to provide ventilation, as temperatures inside can rise quickly.
Having a greenhouse can also invite pests and there are some natural ways to control them if you find you have a problem. Biochemical solutions can be cost-effective and environmentally conscious to control pests such as whiteflies, thrips, spider mites, and mealy bugs.
Praying mantises can be bought as small egg pods, and each one holds around 200 babies. As young and as adults, they will eat basically any pest, as well as wasps. A whitefly parasite will lay 50 to 100 eggs in both pupae and larvae stages of the white fly, which destroys them before they become adults. If you’ve had a whitefly infestation, you know how annoying they can be. Finally, ladybugs spend their lives in both adult and larval stages feeding on mites, aphids, other soft-bodied bugs and all the insect eggs they can find. Adults will consume more than 5,000 insects during their lifetime.
In short, building a greenhouse can be done without hiring a crew or spending thousands of dollars. However, it will take proper analyzing, lots of maintenance, and lots of patience to ensure success.