Some orchids have strict weather preferences, while others can tolerate cold spells and mild drought. Tropical orchids grow in warm, humid jungles as epiphytes, which means they have aerial roots. Though typical home temperatures suit them, they are picky about extremes, such as frost and sun damage. Meanwhile, terrestrial orchids grow in the ground and tolerate much colder temperatures than their tropical counterparts, earning them their other name: hardy orchids.
Ideal Daytime Temperatures
Tropical orchids such as Cattleyas, Oncidiums and Phalaenopsis orchids prefer daytime temperatures ranging from 50 to 90 degrees F. Hardy orchids can tolerate cooler temperatures, even surviving frost in winter. Keep in mind that placing orchids next to glass can elevate temperatures and sunburn the leaves, so you may need to pull a sheer curtain across the window during the hottest parts of the day. (A 10 to 15 degree drop in temperature every night mimics the natural temperature drop orchids experience in the wild and can encourage blooming.
Weather for Tropical Orchids
Since tropical orchids grow naturally in rainforests, they appreciate warm summer weather, filtered light through a canopy of trees and 40 to 60 percent humidity. To increase humidity, mist orchids each morning or place them on a tray of wet pebbles. Air flow is important to balance the humidity. Keep your tropical orchids in breezy locations, such as near a window or in front of a low-speed fan if planted indoors.
Winter chill -- sometimes with the accompanying wind and rains of a storm -- can damage tropical orchids. Symptoms of this type of extreme winter weather include lesions and water-soaked spots on the leaves, burnt foliage and brown coloring. Sometimes wet winter weather causes fungal diseases to develop, too. To prevent these problems, bring tropical orchids indoors for the winter and reduce watering and fertilizing to once or twice a month throughout dormancy. Even in winter, typical household temperatures between 60 and 75 degrees suit tropical orchids by day.
Hardy Orchid Care
Hardy orchids are well-adapted to outdoor temperatures and more extreme weather than tropical orchids can tolerate. They survive freezing temperatures in winter; some even require them to induce spring flowering. However, their preference for cold weather does not mean they can tolerate waterlogged soil. If winter weather includes long, heavy rains, shield your terrestrial orchids under glass or in a cool garage that sees sunlight.
- Orchid Growing for Wimps: Techniques for the "Wish I Could Do That" Gardener; Ellen Zachos; 2002
- University of Hawaii: Orchid Care for the Novice -- An Orchid's Perspective
- The New Encyclopedia of Orchids: 150 Species in Cultivation
- University of Vermont Extension: Hardy Orchids
- American Orchid Society: Preparing Orchids for Winter
- University of Vermont Extension: Growing Orchids Indoors
- Photo Credit Medioimages/Photodisc/Photodisc/Getty Images