The winter solstice, the shortest day of the year, marks a turning point.
Many orchids, after growing vigorously and storing nutrients during the summer, see fit to use those stores for reproduction during the winter months. Get ready to enjoy flowering cymbidium, phalaenopsis, cattleya, paphiopedilums and nobile-type dendrobiums. As spikes start to develop, be sure to stake them early to ensure the best presentation of flowers, especially those that will carry large flowers or a high flower count. Take note to maintain the plant’s orientation to the light source during flower development. Failing to do so will result in flowers twisting in different directions as they reorient themselves toward the light. Also, take care not to expose buds to a blast of bright sunlight after weeks of overcast days or risk the fate of them drying and falling off.
As the days get longer, you should start see new root growth on many orchids. However, with the still-short day length, cooler temperatures, and generally overcast weather (especially in Kalamazoo, Michigan), plants require far less water than during the summer growth period. In fact, some orchids that are native in areas with seasonally dry winters—lycaste, deciduous dendrobium, and many encyclia—need minimal watering to help initiate blooming. Others—catasetums, cycnoches, habenarias, and other terrestrials—will rot and die if overwatered midwinter.
Though most orchids need less water this time of year, it is still very important to maintain humidity in the growing area. Dry heat can cause root tip burn and/or leaves and psuedobulbs to desiccate. It can also cause potting media can get so parched that it is very hard to rewet. Add moisture to the air with water-filled pebble trays or a humidifier. Occasional misting may be an option but only if there is enough air movement to avoid fungal rot.
Visit http://www.aos.org/orchids/seasonal-orchid-care.aspx for additional seasonal tips specific to orchid genra.
Source: A combination of tips from Thomas Mirenda as published in Orchids Jan and Feb issues 2011-2017.