Calanthes...the repotting and care of deciduous Calanthes.

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This is Calanthe Rozel, a deciduous hybrid Calanthe producing numerous 2 inch white and red flowers. Calanthe is a genus of about 200 terrestrial species, which are widespread throughout all tropical areas but are highly concentrated in Asia. The first man-made orchid hybrid created was a Calanthe Dominii, back in 1853, and Calanthe were very popular hot-house plants during the Victorian Era.

There are two types of Calanthe, the deciduous ones which generally have large, silvery pseudobulbs, drop their leaves in the fall, and require less water during the winter, and the evergreen Calanthe which have either no pseudobulbs or very inconspicuous ones, usually keep their leaves for several seasons, and require even moisture year round. This article will involve only the deciduous Calanthe.

There are several deciduous Calanthe species found in cultivation, including C. vestita, rosea, rubens, regnieri, and cardioglossa. These species are beautiful in their own right, and they have been interbred to make delightful hybrids. The species also each have several color variations, including alba (albino), semi-alba (white with colored lip), and various depths of color. The photo above illustrates the breeding and back breeding of deeply colored forms of vestita and rosea.

 

 

 

 




Calanthe vestita var. alba'Snowstorm
Calanthe Rozel 'Cardinal'
Calanthe vestita var. fourneri


The plants are fairly easy to care for, especially if you understand their basic cultural needs. The deciduous Calanthe are native to warm Asian forests which experience a wet spring and summer and a dry fall and winter. They grow terrestrially in deep patches of forest humus, on rotting logs, and among rocks with crevices filled with leaf litter. In cultivation we must duplicate these conditions in order to get the best growth and blooming from our plants.

Basic Calanthe culture: Temperature - 55 to 85F, Humidity - 50%+, Light - bright indirect sunlight 1800 to 2500 footcandles, Fertilizer - balanced fertilizer after new growths emerge in the spring continuing thru early autumn. Watering is most important - keep plants constantly moist after new growths are well-up in the spring, and thru early fall. When the leaves begin to yellow in autumn, reduce water to allow the plants to dry between watering. The leaves will wither and die. Keep the plants humid, but with only occasional dampening of the top of the potting media as the flower stems appear and then bloom. Keep moisture off of the blooms to prevent spotting. Blooming may last several weeks to several months. Divide bulbs and repot as new growths appear in early Spring.

One of the secrets to healthy Calanthe plants is the repotting. So, I'm going to take you step-by-step on how to do it.

First lets start with a pot full of Calanthe pseudobulbs, just as the new growths are emerging from the base of the bulbs. The flower stems were still blooming, so they have been cut off and put in a vase, continuing to last for several more weeks. This pot was left intact for two years without repotting. The oldest psuedobulb was in the center of the pot, and it has rotted away, which is pretty normal. That original pseudobulb produced two growths which bloomed last year, and each of those in turn produced more pseudobulbs: One of them produced two, while the other only produced one. So, we now have five pseudobulbs which can be divided from each other and put into their own individual pots. Even the older ones will produce more growths from their base.


Carefully knock the whole group out of the pot. Dislodge the potting media from the roots, and carefully twist the pseudobulbs free from one another. Do this very gently. The Calanthe pseudobulbs pictured here are a little unusual because they are a nice egg-shape. Many deciduous Calanthes have a "pinched waist" bulb which is very brittle, and the top breaks off with the slightest pressure. This is not always a bad thing. You can allow the break to dry, and then lay the broken top horizontally in a pot of media and it will usually sprout one or two new plantlets which will root and start new plants. OK, so be gentle. Allow the divided pseudobulbs to dry overnight, or you can immediately take some ROOTONE* rooting hormone/fungicide powder and rub it into the breaks and sprinkle the roots. (Note: some growers cut the flower stems for bouquets, unpot the pseudobulbs immediately, and let them sit to the side until new growths are noticed, and only then repotted. Works fine, but you risk not noticing until things are well along.)

Make up a nice rich, "humus-y" potting medium. I use 2 parts "Pro-Mix" or 2 parts composted cow manure, 2 parts fine fir bark, and 1 part perlite. To this I add 1 teaspoon of a time-release balanced fertilizer, such as 13-13-13, for every plant I'll be potting up. You can also use just about any moisture retentive potting medium such as sphagnum moss, coir, coconut husk chips, or even straight fir bark. Do not use dirt in your potting medium.

Usually, as a part of dormancy, most of the roots are dead. I leave some of the old dead roots on the pseudobulbs when I repot. This provides a way to support the bulbs in the pot so they don't wobble around.

The next step is VERY important. The pseudobulb must not be buried in the potting medium or it, and the new growth may rot.


Put some of the potting medium in the bottom of the pot (I used 6-inch plastic pots here) and dangle the pseudobulb in the pot with the old roots touching bottom. Fill in around the roots until about 1 inch BELOW the base of the pseudobulb. NEXT, use fresh medium grade fir bark, coconut husk chips, or quartz gravel to fill-in around the bulbs, this helps prevent moisture from rotting the base of the growths.. The base of the pseudobulb should be just below the lip of the pot.

Do NOT water the plant after its potted. There are no live roots yet, so the water only risks rot. Place the pot on the bench or the windowsill, where it will get bright light, good humidity, and moving air. Once the growth is up about five or six inches, you will see roots begin to emerge from the base of the pseudobulbs. Wait before watering until the roots are at least one inch down into the potting medium. Then begin to water regularly being very careful to protect the new growth, which rots easily if water is left standing on it. Calanthes do like water, and they will use more of it once the leaves emerge, and by early summer, you may need to water the plant 2 or 3 times a week.

With this rich potting media and time-release fertilizer, you won't have to fertilize the plant very much. You will get a nice set of large, green, palm-like leaves about 14 to 20 inches tall, which last the entire summer.

This is what your plant will look like when the leaves start falling off in the fall, after you've stopped watering it for a month or so. A few leaves remain which can be cut off with a sterile pair of shears. Notice this plant is one with the "pinch-waist" pseudobulbs which are very brittle.

The flower stems emerge from the base of the new pseudobulbs in the Fall. The stems generally grow straight-up before arching over, and are often 3 or more feet in length, and sometimes branching. The species normally produce 7 to 15 flowers per stem, while the hybrids can produce many more.

 

 

 

 

 


Calanthe rubens

Calanthe Baron Schroder

 
Calanthe cardioglossa

 

 

©Merkle's Orchids
Nashville, Tennessee