Growing dendrobium speciosum
This is the page I have been dreading. There have been an awful lot of words written and spoken attempting to deal with the culture for Dendrobium speciosum. I guess that on a website dealing with a single species there has to be some information advising how to grow it. If you want in-depth knowledge, you can simply Google it up and I can tell you there are certainly a lot of good articles out there. Rather then prattling on about using this and that, all in very exacting quantities of course, and boring everyone senseless, I am really only going to give a few ideas to take into consideration.
The first thing that must be said about growing D. speciosum is this: D. speciosum, in all of its forms, is pretty easy to grow. I live in western Sydney and I have experienced temperatures ranging from -6C all the way up to +46C. Cold temperatures do not appear to worry it. However, if frost actually settles on the leaves, the news is not going to be good.
Frost protection is the most important thing for long-term success with D. speciosum. One frosty night can set back your plants for three or four years. Defoliation is the problem. Plants will recover however, but nothing is as ugly as a bush house full of leafless bulbs and a carpet of dead leaves on the gravel floor.
I know this from two major events in my growing career when frost got in and left me with wheelbarrow loads of freshly dropped and dead D. speciosum leaves. Heartbreaking in the extreme! Good news is that new growths will not be affected but it will take three years to grow out the old damage. If you do not take precautions you risk losing the new growths just matured the next time Jack Frost pays you a visit.
These days I just live with the acceptance that I must cover my bush house with an extra layer of shade cloth during the winter. I put it on at the start of June and it comes off again in late September. Conditions during this blackout are dark indeed. By June all racemes that are going to emerge are on their way. If I left the two layers on all year round, the number of racemes would be much lower then I get with one layer.
To see really successful flowerings, you must have strong light all year. As strong as you can provide without the sun actually damaging your plants. If your plants are not flowering for you, low light levels will almost always cause it. So, if your plants are housed between your garage and the six foot high side fence, you probably will not have enough light to form flowering eyes between the leaves of the new growths. Without eyes you cannot have flowers. Give your plants plenty of light all year and you are off to a good start with managing D. speciosum.
http://therocklilyman.com/culture/growing-dendrobium-speciosum/