Hothouses For Hothouse Flowers
Orchids are sometimes known as 'hothouse flowers' because many species thrive in warm, humid environments. Having a greenhouse or hothouse is one of the best ways to provide those conditions.
Greenhouses come in all shapes and sizes. Some are glass and as large as an ordinary house. Others are little more than a doghouse-sized structure covered with translucent plastic. But all serve the same purpose: to let light in so that some wavelengths of light will come back out again, while others are trapped inside.
Because of the nature of the greenhouse effect, most of what remains inside are long-wavelength infrared (and, therefore, invisible) light waves. That produces a hothouse, a house that remains hot, even while the outside may be quite cool. A greenhouse outside in 40F/4C weather can be quite warm if there's adequate sunshine. In fact, most greenhouses are ventilated because they tend to get too hot!
At the same time they are trapping heat, they are efficient at retaining moisture. Moisture can be put into the air around the plants by a combination of methods.
Hand watering plants will produce a certain level of humidity simply through evaporation. As the heat warms the soil and pots a certain amount of water vapor will rise above the plants. The condensed water on the glass of greenhouses is evidence of this.
Automatic systems are even more efficient at maintaining the 40%-70% humidity level that many common orchid species enjoy. Hailing from Hawaii, tropical jungles and other naturally humid regions, they thrive in conditions that we would find uncomfortable. Timed misters, small sprinkler heads both near the plants and overhead, can easily keep the interior wet.
Here again, it's more often the case that the effect is too easy to produce rather than too hard. The same ventilation system that allows excess heat to escape can allow excess moisture to leave the greenhouse. Too much water can be as big a problem as too little.
Mold, mildew and other troublesome organisms thrive in those high humidity conditions. That creates a maintenance and care effort for those who want to keep their orchids healthy. Wiping off mildew, spraying with mildewcide and other needed activities can keep a greenhouse orchid gardener very busy indeed.
The expense of building a greenhouse is a similarly mixed proposition. Depending on the size needed, they can run from very little (when made from home made materials on hand) to thousands of dollars. But the cost is often regarded as well worth it by those who find it so much easier to maintain their precious rare plants.
It also provides a convenient place to do some gardening almost all year 'round. Temperature control can be enhanced by artificial means, along with the watering systems. When the weather outside is frightful, the greenhouse interior can be delightful.
