People aren’t the only ones who suffer during the winter. House plants do, too.
Tropical orchids are especially challenged when temperatures fall below freezing, heaters take all the moisture out of the air, and the sun barely clears the horizon. These conditions are never found in the rainforest.
To combat these very real threats to their hobby, growers have informally developed a set of “winter rules” which go into effect from mid-November to mid-March. While there is no guarantee of success, following these principles greatly improves the odds of happy plants.
- Keep temperatures above 60 deg F – This is the easiest rule to follow because the grower will quickly notice uncomfortably cool air. One remedy is to relocate the collection to a warmer part of the house. Also, closing the draperies at night can significantly reduce drafts. Lastly, the addition of an electric space heater does wonders. Since orchids don’t like wild temperature swings, we recommend oil-filled radiant heaters which gradually warm the area.
2. Keep humidity above 50% – Most people can’t feel the difference between 50% and 40% humidity but orchids will show their stress in the form of yellowing leaves and shriveling buds within a few days. Every grower should have a small gauge that sits among the plants and displays 0-100% humidity. If the device also records highs and lows and measures temperature, that’s even better.
One way to increase humidity is to use a tray filled with water and topped with a grate or pebbles. Orchids sit on top and moisture evaporates around them. This tray can be either a do-it-yourself or preassembled project. For larger collections, consider a small one gallon humidifier. Orchids don’t like droplets condensing on their leaves so we recommend the humidifier types that allow for fine manual adjustment of vapor.
3. Give as much sun as possible without burning – Despite its ever-changing low angle and too brief appearance at this time of year, the sun is both welcomed and tempered. Orchids need light to grow and bloom but the intensity of the sun is critical. For example, one hour of full mid-day sun on a Phalaenopsis plant may result in blackened leaves. Conversely, several months of a dimly lit room may prevent a Phalaenopsis from blooming or having more than just a few flowers.
The trick is finding the ‘right spot’ in the house where the exposure is bright but not too bright. Seasoned growers habitually feel their plants because the leaves tell the story. Warm leaves indicate too much sun. Try adjusting the position of the orchids slightly or adding shade in the form of a sheer curtain or partially turned blinds.
Some growers go so far as to try to mimic equator-like day lengths of 12 hours as found in many native orchid habitats. This ambitious plan requires supplemental grow lights and timers. When it gets dark at 5pm, the lights turn on for four more hours.
Let it be known that spring is just around the corner and with it come new orchid challenges. But, from now until mid-March, we have our winter