Ideally, most orchids do best in the 70’s and 80’s, going cooler at night. During mid-summer, when they receive week after week of 90 degree temperatures, they need a bit of extra TLC to keep them happy.
Misting your plants will help to cool them off. In very humid climates, one needs to mist very lightly so that the plants don’t stay too wet. In a hot and DRY climate, one can mist more heavily to create a bit of humidity. The water droplets on the leaves help to cool off your orchids’ leaf tissue.
Shade your plants heavily during hot summers. Think of yourself sitting in the hot sand at the beach. If you sit in the shade, you feel much cooler. Taking a dip in the water (or misting yourself) will bring down your body temperature. The same holds true for plants.
Back off a bit on fertilizer when extreme heat hits. When it’s 95 degrees plus in the greenhouse, I very rarely feel hungry during the day. Orchids also seem to slow down their growth in extreme heat. Skip a week or two of food every so often during those high heat weeks to give your plants a break from the high nitrogen rush!
Air movement is also a key. Just as I like to stand in front of a fan during a warm spell, our orchids also will benefit from extra air movement.
The flowers on those few orchids that are brave enough to bloom this time of year don’t last very long. This time of year our Phalaenopsis fold after 4-6 weeks, whereas during the cooler winter/spring season they last 3-4 MONTHS. This is why most orchids bloom between Thanksgiving and Mother’s Day. Summer is more of a “growing” season for plants.
Try not to add undue stress to your plants during extreme heat. Usually it is fine to repot throughout the summer months. However, when extreme heat hits, it is best to wait a week or two until things cool off. We usually try to repot our most tender orchids in Springtime (March through May), leaving some of the sturdier varieties (i.e. Cattleyas and Dendrobiums, etc.) for summer potting.
If growing in a bark mix, watch for moldy bark (snow mold) this time of year. It is very common due to the high humidity levels. It helps to use a fungicide periodically during very humid months. Physan 20, Captan, and Phyton 27 all will help to keep mold and rot at bay. If you do see mold in your mix, it is usually best (and cheapest) to simply repot the plant in fresh mix.
Stay cool,
Liese