Weather Protection for Orchids

Outdoor Protection

• Plummeting temperatures in winter can cause orchids to suffer from frost and cold stress, and frozen soil can prevent orchid roots from taking up water. To prevent this outdoors, cover orchids with frost cloth -- sold at hardware stores -- or a similar material, such as a sheet or towel. This insulates the orchids. You can also apply mulch around the base of reed-stem orchids such as epidendrums, hardy in U.S. Department of Agriculture plant hardiness zones 8 through 11, to regulate the soil temperature and keep your orchids hydrated.

Watering on Freezing Nights

• Adjusting your watering schedule during winter can help orchids deal with freezing temperatures, too. When you anticipate a freeze, do not water orchids for the day before it hits. Keeping orchids dry means less water in the soil that could freeze and less potential for frost damage. Once the freezing temperatures arrive, water your orchids thoroughly, because most groundwater and tap water is about 63 degrees Fahrenheit -- a warm enough temperature to keep orchid roots from freezing on a chilly night. However, you should not water orchids like this if they have just been watered, because overwatering can inspire fungal problems and root rot.

Moving Orchids Indoors

• The most effective way to protect orchids from cold stress is to move them indoors for the winter. This is especially helpful if rain, snow or high winds threaten to damage your orchids. Placing the orchids in your house or a warm garage allows you to control their environment, including the temperature and humidity. You can place them indoors for the entire winter or just for a few days when freezing temperatures are anticipated.

Ideal Winter Temperatures

• When you move orchids indoors for winter, you'll need to keep temperatures cool enough to stimulate flowering during the next blooming season. For cool-growing orchids such as cymbidiums, hardy in USDA zones 10 and 11, this means about 50 degrees F at night; for intermediate temperature orchids such as cattleyas, hardy in USDA zones 10 to 12, this means 55 to 60 degrees at night; and for warm-growing orchids such as phalaenopsis, hardy in USDA zones 10 to 12, 65 degrees at night is ideal. Temperatures should be 10 to 15 degrees higher by day.

Preventing Heat Stress

• Although orchids appreciate warm, humid environments similar to their native jungle homes, they sunburn easily and can wither, shrivel or turn leathery if heat is too intense. When temperatures soar above the mid-80s, increase watering to keep your orchids hydrated. Keep humidity at 40 to 60 percent by placing potted orchids on trays filled with wet gravel or by using a humidifier. To keep the air circulating in this humid environment, turn on a low-speed fan or provide a similar air source to help prevent fungal problems. You should also shade orchids when the sun hits them directly, especially if they show symptoms of sunburn such as pale, bleached leaves or red-tinged foliage.