Friday, October 10, 2014

Dendrobium cuthbertsonii bicolor

This is one of my many plants of this charming species.  It comes in a rainbow of colors including this bicolor form, and has flowers that last for months.  Dendrobium cuthbertsonii is from the highlands of New Guinea, is a micro-miniature plant, 2 cm or smaller with huge flowers.  It is cool growing and does not thrive unless the temperatures are kept down, but very high light will compensate to some extent for higher temperatures.  I grow some plants mounted and some in pots in live sphagnum and all do well for me.  This plant is a bicolor and has unusually large flowers.  It is probably a polyploid.






16 comments:

  1. Wow! Those lower petals are stunning.

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    1. How can one not love this species with so many variations in color. Thanks!

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    2. I couldn't agree more. Just when you think you've seen them all, some new spectacular variation pops up!

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    3. The trouble is that I want them all.

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  2. It is a very beautiful plant with those tones of color. Fantastic culture. Congratulations

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    1. Thanks ever so much, Angel. This is my favorite orchid.

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    1. Thanks, Mihaela. Appreciate the visit.

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  4. It is a very nice individual, Ron. The stripes on the lip is very pretty. You mentioned about the high light under higher temp in OB discussion. I didn't understand it for a long time, but after reading a bit about plants, I started to think that it may be something to do with the balance of respiration vs photosynthesis. Both respiration and photosynthesis rates increase with temperature. During the day, when both is happening, there is an optimum temperature where (energy gain by PS) - (energy loss by respiration) is highest (and this optimum temp is species specific). At night, lower temp is better because of the lower respiration rate. So by using stronger light during the day, you might be compensating the more energy loss during the warm night. Sorry for being a bit too detailed, but I really appreciate to hear this wisdom of yours! Now I'm thinking that if I can't get cold enough night temp for cold/cool growers, it may be better to increase the day length dramatically (e.g. 18h day).

    Anyway, I recently started to grow this species. You are the master of this species, and I'd like to hear how you grow it. You have already mentioned lots of stuff, but I'm specifically curious about watering. They are supposed to be kept moist. But one person's definition of "moist" could be different from mine. Do they suffer from root rot by overwatering? My enclosure is pretty similar condition to yours (now around 70/55F, RH 70-80%, decent air flow, 6" from T5HO). For sphag in 2" clay pots, I'm watering every other day, and it never dries, and I would say it is fairly wet (more than moist). Do you think I should let it go a bit closer to dryness?

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    1. I appreciate your analysis of the business of giving this species more light, Naoki. I'm not sure, however, that it would work for all cool-growing species, since some of them can't take high light. I've found that Masdevallias, for example, do not flourish or bloom under too much light and have had to decrease the amount of light I was giving them, both by using fewer bulbs and by moving them farther away from the lights. Increasing the day length may help and I do that (up to 18 hours) but have not noticed that makes a difference.

      As to D. cuthbertsonii, I grow it both potted an mounted. Mounted it does not stay as wet as the potted plants but I do use a pad of moss over the roots. I water daily but have put more inert drainage material in the pots to keep them from being too wet, and have noticed that I have to change the moss frequently (yearly) or I start to get roots dying off. One trick I've learned with moss is not to pack it tightly but quite loosely - that allows air in and allows excess water to drain away.

      This particular plant is mounted and dries out rather quickly (it's near one of the fans), and I'm using it to test find out a bit more about just how much water to give. It has some moss around it, but not a lot. It's blooming well, but the plant looks a bit shabby, so I will probably have to give it just a bit more moisture either by moving it away from the fan or by put a bit more moss around it.

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    2. You are right that some species can't take stronger light. But it is good to know that you didn't see a difference with the longer day length.

      Thank you for the D. cuthbertsonii tips! I've always wanted to grow Oxyglossum, but I was always a bit scared. I guess that I have to learn by observing them closely.

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    3. In my humble opinion D. cuthbertsonii is one of the easier Oxyglossums. The only one that is for sure easier is D. pentapterum and (in warmer temperatures) D. laevifoliuum. That one, however, does not do well in cooler conditions.

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  5. This is a very interesting discussion. Thanks to your blog, Ron, I have found that success with this species depends on three things in this particular order: 1) high light, 2) high humidity and finally 3) temperature. According Andre Schuiteman's book, A Guide To Dendrobium of New Guinea, although it isn't common, it is found as low as 600 meters, so it must be pretty tolerant of warmer temps in its habitat. However, you must have both high light and high humidity. I have also switched my potted plants from moss to a mix of small orchiata bark and charcoal. This is similar to a mix the Atlanta Botanical Garden uses for pleurothallids, but they also add permatil. Because it is so humid most of the year here in Atlanta, the moss stays too saturated, even if I also add tree fern fiber or some other sharp draining additive. So far, I am seeing great results with root growth.

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    1. I agree and think you are on the right track with changing mixes. I still use live sphagnum but have found that I have to be a bit more careful to change it. I had a lot of root loss on a couple of plants because I let them go too long before repotting.

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  6. Another very nice one. Particularly in the color separation which I always find as a fine trait in bicolors.

    Ron do you ease cuthbertsonii into higher light levels? I have a difficult time keeping mine as close as you do to the lights. At least that is what I gathered from the pics of the species I saw mounted.

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    1. I haven't but probably should, Jon. A couple of mounted plants that I stuck right up against the lights after I got them have taken a while to adjust and one of the last I've kept further away in the hopes that it will adjust more quickly.

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