The problem with Dendrobiums is.....which type. I assume
the Den. "phal" type. As I said before easy if you are in tropical places. Miami, Hawaii, Tropical SE Asia.,.Northern Queensland, Australia. etc
Not so easy here where I have mine in a glass-house and I should give up on them and grow more rewarding orchids.
Here is the link to the Canadian Orchid Congress Notes which are probably more appropriate to your growing conditions.
http://www.canadianorchidcongress.ca/cculture/dendrobium.pdf
Here is part of my mess of a collection. Why are these orchids in different sized or no pots? Because when you have oodles of orchids you want to water them all at once. So you vary the mixture or the type of pot. Why are they growing stuck on a wall? so they can get air movement.
As for the all gravel mixture. The answer is Yes especially if you have tropical conditions which cause orchid bark to deteriorate quickly. .
{{gwi:170345}}

Here is a link that might be useful: assorted Dendrobiums

This post was edited by arthurm on Wed, May 21, 14 at 2:27

Thanks so much :-) With a gravel mixture, lets say at 70-75 degrees, and 2 hours of direct morning sun, would twice a week be sufficient for watering?

Would every other day be too often?

Just trying to determine a minimum and a maximum to work off of.

Which type of Dendrobium do you have? Hard cane or soft cane?

You could post a photo or describe the plant.

Without seeing the plant, I would say every other day would be too often. Again, it depends on how dry the environment is, air movement, etc.

Jane

It is a hard cane. I havent done anything with it since I got it, apart from watering it a couple times. It is under two CFLs in my bedroom, a 13 watt and a 26 watt, in a north window. One of the leaves is yellowing now and getting wrinkly but the other parts of the plant seem healthy so Im assuming it is just getting rid of old growth.

It is growing on what I can only describe as part of a dead stump. I am entirely unsure how i would go about repotting it in a different medium, and as i have thus far procrastinated with no real negative repercussions, I am tentatively deciding not to change it at all.

Maybe it doesnt mind rotted log culture.

New growth, was present at purchase and has continued to grow.

The whole plant and its setup

I would leave it alone. Pot in pot is perfect. If the roots decide they don't like the stump, they'll grow into the space between pots. These plants are tough!

Jane

Bump.

Still debating growing medium with this one. All the roots are dead but the new growth, so I want to switch it out before the new roots establish themselves.

I have lava rock, aquarium gravel, and coarse bark.

As I said before it is a warm growing hard cane Dendrobium. The advice from the "tropics" here is, air movement, warmth, plenty of watering but must dry quickly.
Easy in Queensland, Australia where they are the dominant orchid in many collections, not so easy here in the "sub tropics" where the dominant orchid in many collections are Cymbidiums.
Maybe try 50% bark, 50% lava rock. If the coarse bark chunks are really large, cut them up with secuteers.
Maybe use a smaller pot after you have removed most of the remains of the current medium, enlarge the drainage holes.
Look for more culture notes written for Northern USA.

Looking at the photo, the roots do not appear dead to me. They belong to the older canes which could flower again. The canes appear healthy and you risk losing flowers and setting the whole plant back.

I have torn roots off wood pieces and the plant survived but did set it back a few years. I wouldn't do it again but that's up to you.

You could try soaking the piece of wood to try and loosen those old roots and see if you can get them off without too much damage.

Personally, I would leave the plant the way it is inside the pot with the wood. If you want you could sprinkle some bark pieces or rock to fill in the gaps.

Jane

The roots dont look dead, but they are papery and feel hollow.

Anyway it is too late. I removed it yesterday. It is just sitting atop some moist sphagnum right now.

Was thinking of putting some sphagnum over the top of this pumice stone and mounting it, then setting it in a pot, and filling the space with bark...i will leave it til later tonight in case anybody thinks it is a bad idea.

Idea may not work because I am unsure what to use to attach it to the rock.

Here is a link to a long previous discussion that may help.

Here is a link that might be useful: Previous discussion

Thanks, Arthur. I went ahead and read it. Every little bit of knowledge helps me make up my mind ;-)

Laura, where do you live? What are your conditions? Can you put this plant outside in the summer?

Personally, I wouldn't plant on a pumice rock. You are complicating growing an easy growing plant if it is given enough light and air.

Do you have space limitations? I grew these plants easily in NY in small pots with bark. Now that we live in Florida, I've changed how I'm growing them. I'm moving them to baskets with some large bark.

They take quite a bit of sun and won't grow well under CFL's as their only light source. I used CFL's to finish spikes in the fall when they had to come back in the house.

That new growth on your plant, requires good strong light to develop properly and flower. The older canes might flower, but with some root damage, I'm not sure.

Light is your biggest factor right now. Increase light, put it outside if possible and pot the plant in a pot. You could put the pumice inside a clay pot but I don't see the purpose except to weigh down the pot.

Give me some more info.

Jane

I attached the orchid to a lava rock. The purpose being stability. Then I set it in a pot and filled the space with coarse bark.

I could put it outside where it would get about 4 hours of morning sun, but it would be getting some sun up until 11 oclock so Im afraid of the risk of sunburn. The 11 oclock sun is really strong, especially a little later in the summer.

I am not too concerned about flowers. It wasnt flowering when I got it. Most of my houseplants dont flower. When and if this one flowers, it will just be a bonus.

If you think midday sun wont bother it, I could even attach it to the outside of the rail in a clay pot, and water it every day.

I would need to know minimum and maximum temperatures for it though. It has been below sixty a few nights this week. And it gets close to 100 for long stretches in the summer.

I live in Wisconsin, zone 5.

Heres a pic of the bark mix.

This post was edited by Lauraeli on Sat, Jun 14, 14 at 16:40

Laura, you don't want to grow orchids without flowers. Trust me! They are not the most attractive plants, they need to flower.

I would gradually get the plant accustomed to the outdoor sun. The new growth needs sun to grow. Your plants will decline without enough light. Orchids need to flower, they need enough light to stay healthy. Low light will not work with this type of orchid.

Hang it on the railing to catch the early morning light. I'm assuming your porch faces East. Move the plant back after 11am. After a few weeks, leave the plant there all day.

Morning sun is your best light. It would work for most of your flowering plants.

Do you have a yard?

Jane

I grow mine in long fiber sphag moss and perlite.

I dont think my orchids are unattractive at all.

I have a lot of different kinds of plants. I like variety.

For instance, I think my orchids are more attractive than my spider plants. And spider plants are grown for their foliage.