| I am a commercial grower in SW Florida. Obviously I can not bring thousands inside.
Everything is outdoors under shade cloth exposed to the weather. That said I have left them unprotected into the low 30s every year. Once the weather report said 38 and I woke to 28.
I did not lose any orchids even down to 28 (some leaf damage hurt their looks for a year before they leafed out new)
Dendrobiums, Phalaenopsis, Zygopedilum and Oncidium intergenerics just about anything did fine.
Normally we wrap out shadehouses in plastic for the winter. This will raise the temperature on a cold night about 6-10 degrees. Remember if you plants are close to your house, that the house is the biggest radiator you could find.
In Florida our homes often have a pool and a screen cage around the pool. Temperatures inside the screen cage is usually 10 degrees hotter than the weather reported temp.
If you are really worried, then cover the plants on the coldest days. A simple sheet over the plants will retain a lot of heat. Keep in mind that wind will remove heat rapidly so keep them in a sheltered area.
It is a pain to cover the plants and then remove it each day. You might consider getting PVC pipe and building a frame around the orchids. Keep it fairly close to the orchids. Then you could drape clear plastic over the frame and remove it each day.
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jerry  |