February 23, 2014


As the sun becomes warmer under glass, both spring forced bulbs and early blooming cool-loving orchids make a nice display in the greenhouse. Note the Dendrobium kingianum on the right, a cold-loving Australian orchid.

Of all the orchids in the genus Dendrobium, D. speciosum may just be the largest. This plant, in a 24" basket, now weighs nearly 60 lbs, and although hardly perfect, with some leaf burn, it is impressive with many, long spikes of flowers. It's so big, that it's difficult for me to photograph it.
As many of us in Eastern North America discovered, this weekend in last February was our fist taste of spring, that is if you can call 48º F spring. With temperatures rising above freezing, I decided to repot some orchids - a long overdue chore - is it OK to admit to you all that I only decided to do this because while looking for more bags of bird seed on the back porch,  I found a big bag of orchid repotting supplies that I had completely forgotten about? - with tshirt weather under glass, brilliant sunshine and  only the sound of winter birds outside the glass, I could use some orchid-repotting therapy right now - especially after 4 snow storms in one week.

I don't have the perfect greenhouse for raising many orchids, we keep a few in the house during the coldest months of December and January, with many occupying windowsills and plant windows, where they sit on gravel trays which provide some moisture, but most of these orchids are ordinary super-market purchases ( still beautiful, but not botanically interesting to folks like us). So although we keep these phalaeonopsis and paphiopedilum, the lady slipper orchids, warm and safe, as they like the same temperatures we do, and throughout the winter, they provide us with at least some hope that warmer weather will eventually return. We can't grow all of the orchids, but I do keep a few selected rarer species - the real treasures, out in the greenhouse, where I am limited to those species that can handle the colder temperatures, of which, there are plenty.

Cymbidium orchids have been bred into thousands selections, which thousands of named crosses now available. Most are cool to cold loving plants, and will thrive in a cool greenhouse in the north, or outdoors on terraces and in containers in areas that do not freeze, such as Northern California. This selection was bred in Massachusetts, and it is called 'Bay State'. I leave plants outdoors until a hard frost hits, and I bring it in just before it freezes, which stimulates it to form spikes. There are cymbidums to please most every taste, and varieties that will bloom in most every month.

You may think that all orchids need tropical rainforest conditions, but that's just not true, as there are many which prefer cool or cold winter temperatures, and even some which can handle very light frosts.Orchid collectors divide  the great orchid family (one of the largest plant families in the world) into three broad groups, based on cultural conditions - cool growing, intermediate and warm. Cool growing orchids (those which perform best with some periods of either near freezing or night time temperatures around 40º are best for us, while we find some success with intermediate orchids, which often can handle temperatures around 50º at night. Warmer orchids are not growable, as they mostly demand hot and steamy conditions, and cannot tolerate  temperature swings often preferring constant temperatures above 70ºF.

This Dendrobium aggregatum, a miniature creeping dendrobium likes to grow on a slab of tree fern bark. I purchased this young plant in a pot, but I am repotting it to grow as a 'slab' orchid. I first remove the old growing bark, wash the roots carefully, wrap them in long fiber sphagnum moss which was soaked in warm water, and then wired the entire plant to a square block of tree fern bark. I a few years, it will completely cover this slab, when it blooms in the spring.

Once wired and pinned, I wire the tree Fern bark to a wooden slab, which will allow me to hang the plant in the greenhouse during the winter, and outdoors, under trees in the shade in the summer, where the plant can enjoy summer downpours and thunderstorms. When it blooms, it could look like this:

Even in a cold to cool greenhouse in New England, there are many orchids that thrive in this atmosphere. Many are in the Dendrobium clan, but note, not all dendrobiums like cool temperatures, as the genus is large, and has species that live across the temperature spectrum. With orchids, it's generally elevation that dictates what conditions they prefer. If you think of Borneo for instance, you may imagine steamy, tropical jungles, but there are mountainous areas that reach near to the snow line, and there are orchids at most every level. Mostly, I grow Australian dendrobiums, or those from higher elevations in Asia.

A young Dendrobium aggregatum freshly wired to a slab, and soaked for an hour, enjoys some mid-winter sunshine in the greenhouse where the snow is nearly 3 feet deep just pass the glass wall.

A Brassio Cattleya cross, is growing out of its container. It's clearly time for repotting before it sends out new growth which will bloom next autumn. One must be careful in removing a plant like this from a pot, as you will need to be careful not to damage the newer, white roots, which adhere themselves to most any container.

This plant I potted in a clay orchid pot, which I will hang from the rafters with clips. It is centered in the pot, and sits at the same level as it sat before. Epiphytic ( growing on tree branches) this orchid like most, needs perfect drainage.

This is a cross between a Neofinetia falcata orchid, and a Vanda. Both species are related, so this is not an odd cross. It should produce flowers larger than the traditions Japanese Neofinetia's which one sees in so many Japanese plant collections, but with the size and perhaps color of the vanda clan. This is a genus that liked to grow in an airy mix, and although I could grow it in a pot, I have decided to pot this up in a wooden slat basket.

I place the Neofinetia Vanda cross in the bed of Sphagnum, and then use a good quality orchid bark mix to fill in around the roots. A bit more sphagnum, and I am done.

Once repotted, this neofinetia Vanda cross is well watered.

I am using a traditional Japanese container for one of my Neofinetia orchids, preferring to pot it in the traditional Shogunbutsu method, where the plant is placed on a mound of sphagnum. In Japan, many orchids are grown in this way, and most are native Japanese orchids, which were so popular during the Edo period, and said to be raised by the Shogun. Check these amazing images out of an orchid show in Japan. I try to grow them like this, but not nearly as nice.

While repotting my Neofinetia falcata, I need to do some housekeeping, as I had been slacking. Old fans which had died, needed to be removed, as well as dead roots, and dead flower stems, This is a genus that like to form clumps, and it makes a better specimen plant if allowed to grow large, but to get them to any size, one must keep the plants clean. I could have divided the plant also, but decided not to.

Now repotted with a nice, clean mound of sphagnum, is still looks nothing like the specimens one sees in Japan, where this orchid had a strong, passionate following. Here is what it will look like when it blooms for me, in August.

Dendrobium speciosum, another view, as the sun begins to set.

I keep trying to get a good photo of this big Dendrobium speciosum. Here is what it looked like when I saw it in Tokyo at the Orchid World Grand Prix a few years ago. HERE

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  1. Some catleya species would do very well in your conditions. How hot does your greenhouse get in the summer? The range of temperatures is the hard bit to find orchids for, rather than just the low end. I imagine that pleoines would do well for you if it doesn't get too hot. You should check Santa Barbara orchid estates. They have a great selection of orchids that can be grown outside in California.

    1. Justin, I used to grow some cattleya, and they did fine. My greenhouse gets very hot in the summer, but I have shade cloth. It still reaches about 105. degrees. Most of my orchids have come from Santa Barbara Orchid Estates, that's where I found the Dendrobium speciosum, selection, and their cymbidium choices drive me crazy! There are SO many!


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