It looks like we are in a cool weather pattern which got me thinking about some of my orchids and holiday cacti. When attempting to grow tropical plants we are met with the challenge of mimicking their native habitat which is difficult inside our homes; we can allow Mother Nature to take care of some of this, outside, for now. Move some of your orchids, holiday cacti and clivia outdoors for the remainder of the season because we can initiate bud set through managing day length and nighttime temperatures.
The flowering of many plants (including some native species) is initiated by how many hours of light and dark the plant receives in a 24-hour period. Likely the most famous tropical that is photoperiodic is the poinsettia. How many people have tried to initiate the bracts to turn red by sticking their poinsettia in the closet for 12 hours each day? I usually just buy new ones each December!
There are some other photoperiodic bloomers, however, that I hold onto year after year; and I have discovered a reliable way to get them to bloom that is quite simple. I leave many of the plants outside through the month of September (or later, depending on the weather) so that they can naturally experience shorter days, and longer, cooler nights.
I send my clivia, holiday cacti and several different species of orchids outdoors for some chilling time this time of the year. I have had amazing success with this very simple plan. Follow the forecasted weather and take note of nighttime temperatures. If a couple of nights dip below the desired temperature bring the plants in until conditions become desirable again.
The holiday cacti (the Thanksgiving, Christmas and Easter cactus) can be left outside to experience the longer and cooler nights of late summer and fall until nighttime temperatures consistently drop below 50 degrees. There have been some years when the plants have already set visible buds on the stems while they are still in the protected corner behind the garage.
We typically think of orchids as being sensitive to the cold when, in fact, several species are quite appreciative of a little nighttime chill. The very popular Phalaenopsis, or butterfly orchid, appreciates a light breeze and some cool evenings to about 55 degrees. Once nighttime temperatures drop below 55 degrees bring the plant back indoors, provide bright light and fertilize with a balanced fertilizer every other week.
Other species of orchids that like some chilling and light treatment include Dendrobium, to about 55 degrees; Oncidium can go as low as 45 degrees; and Cympridium to about to about 55 degrees. Remember that there are many different orchid species so for the enthusiast it is best to get some comprehensive information on the specific species you are growing.
Cattleya will be content to stay indoors or if they are outside in a shady area for the summer bring them in when nighttime temperatures consistently drop below 58 to 60 degrees. Brassia, or the spider orchid, prefers a warmer reality as well, so bring this one in along with the cattleya.
Clivia will also benefit from some chilling. I leave mine out until temperatures dip below 50 degrees. Once they are brought indoors, I set them in bright light and water sparingly. They have low water requirements in the winter and reward me with blooms based on this neglect. For many, although not exclusively, a dry period in the winter is recommended. This is where understanding the native habitat of a plant comes in handy. If you come from a place where it rains all summer and is dry all winter then this is likely what you will prefer in someone’s house in Kentuckiana. Keep Clivia, Dendrobium and holiday cacti on the dry side during the winter months.