Potting medium for dendrobium - Orchid Board

Lady Oscar · #1 06-23-2016, 08:53 PM

I'm not sure exactly what my Den. suzukii x Den. tobaense is potted in, but it seems to involve some moss, and I've noticed it stays pretty moist for quite a while in my humid climate. Being paranoid now, I'm thinking of repotting it to check out the roots.

The medium I have right now is "Better-Gro Special Orchid Mix" (https://www.amazon.com/Sun-Bulb-5002.../dp/B005OK9KRK) which is fairly coarse. Would it be better to go with something finer? I'm concerned that this may drain _too_ well, since it sounds like this dendrobium wouldn't necessarily want to dry out completely. I'm also a bit concerned about support, since it's very tall compared to the pot diameter (and I haven't found a place to buy rhizome clips that doesn't have ridiculous shipping costs for Hawaii).

It's growing some new leaves out of the top of the tallest cane and has one newish aerial root, and one bloom left.

voyager · #2 06-25-2016, 05:57 AM

Hi Lady Oscar,
I'm on the windward side of Big Island in an area that gets 150+ inches a year of precipitation.
My present methods may not be of much help to you as I now grow them very differently than you are trying to do and I used to.

Now, with that said, Dendrobium is such a diverse genus that you cannot generalize growing conditions for the whole genus.
I'm not that familiar with your specific Dendrobium species, but they are from section Formosae. I have grown, D. cruentum, bellatulum, a couple of Foermosae hybrids and several other species and hybrids all with the bright orange throat. I grew all of them similar to the cool dry winter rest types, just not quite so dry as most of them. I grew them in a mix of about 50 to 60% 3/8"minus pumice rock and 50 to 40% chopped NZ moss by volume. If you've a mind to try it, you could substitute black cinders for the pumice. They did fairly well for me. They would probably do quite well just in a moss medium as long as they had good drainage and air circulation, exposure to breezes and such in an outdoor environment.
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EDIT:
My memory just got jogged:
If you are growing in an indoor environment I suggest having a fan or fans moving air over and around the orchids. That would take care of the air circulation problem.
When I grew them [as many as 75 or more] in home, I had fans everywhere. When in a closed up environment with stale air, they are very appreciative of it and show it.
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Summers they should like a fair amount of moisture. The moss shouldn't be a problem there as long as it has good drainage. the water cannot stagnate.
Winters is where they might like it drier. I would think that with very good air circulation and withholding water somewhat letting the moss almost dry out, then the moss wouldn't be a problem there either. You would need to become attuned to the plants wants and needs to become artful at it.
I hope that wasn't too esoteric for you to follow.
God luck with your Formosae types.

estación seca · #3 06-25-2016, 03:57 PM

Like Voyager said, different plants need different treatment. I think this group of Dendrobiums really needs not to dry out during the growing season. That might be one reason some people say Formosae Dendrobium species are hard to keep alive. (Hybrids are supposed to be a lot easier.)

You can probably figure out who the grower was; their name might be on the tag. Contact them and ask for advice.

Lady Oscar · #4 06-25-2016, 09:35 PM

voyager and estación seca, thanks for all the great information and advice! It's good to know that the plant likes it moist, since I had been letting it dry out more and it didn't seem to like that much (dropped blooms and a bud) and when I watered more often started growing new leaves, but I was worried it might be bad for the roots. I'm going to leave it be in its original pot for now and monitor the dryness level with a skewer. When I do repot, I'll try the black cinders/sphagnum combo.

My living room is _very_ breezy (I had to move this plant off the kitchen passthrough after it was knocked over by the wind twice!) but I might try a sheltered area outside when it gets hotter and we lose the trade winds. If not, I'll make sure to have the ceiling fan on. How much light would it be likely to want?

I'm very attached to this plant and love its weird little flowers, so I really appreciate the help! There isn't a grower name on the tag, unfortunately, but if I can remember which booth I bought it from at the farmer's market I can ask them next week. (There are three plant vendors there with orchids most weeks!)

estación seca · #5 06-25-2016, 09:43 PM

Other people on the board here have mentioned that H&R Orchids grows a lot of Dendrobium hybrids.

Lady Oscar · #6 06-25-2016, 10:08 PM

Quote:

Originally Posted by estación seca

Other people on the board here have mentioned that H&R Orchids grows a lot of Dendrobium hybrids.

They don't list this one in their current price list (as best I could tell after doing battle with their web page's desire to hijack my browser and pop up weird ads), but I've been wanting to check them out, anyway....