Dendrobium kingianum had parts that grow the dry up.

[fooferdoggie]

we have some lower humidity in summer but it is fine in winter. 58% right now. it seems pretty happy. the little ones are growing pretty fast now they started out as a single bulb they each have 5 shoots now since April or may.

[estación seca]

Shoots expand rapidly because the plant pumps large amounts of water into a structure that is almost, or completely finished with cell division. If the plant can't pump enough water, the shoot collapses and dies. It can be caused by poor roots, infection blocking water flow in plant tissue or insufficient water to the roots.

[fooferdoggie]

Originally Posted by estación seca

Shoots expand rapidly because the plant pumps large amounts of water into a structure that is almost, or completely finished with cell division. If the plant can't pump enough water, the shoot collapses and dies. It can be caused by poor roots, infection blocking water flow in plant tissue or insufficient water to the roots.

most of the roots seem to be outside the moss.. though humidity is around 60% they are white and look healthy. so may just water even when the moss is wet? it gets misted once or twice a day too.

[estación seca]

If the roots are outside the moss they won't pick up much water from the moss. If mine grew like that I would try to wet the aerial roots often. I don't have a sense of how much water Dendrobium roots take up, and how fast, the way I understand Vandas. My Dendrobiums have roots that almost all stay in the pot. Are there healthy roots in the moss?

[fooferdoggie]

hard to tell how many roots are under the moss. you can see there are a ton outside.

[Roberta]

Personally, I'd be inclined to remove that moss ASAP... pot into bark or other open medium. The roots outside the bark look happy, the ones in it not so much. And this is a good time to do it - as spring approaches, there will be active rooting.

[fooferdoggie]

Originally Posted by Roberta

Personally, I'd be inclined to remove that moss ASAP... pot into bark or other open medium. The roots outside the bark look happy, the ones in it not so much. And this is a good time to do it - as spring approaches, there will be active rooting.

should I keep the outside ones out of the bark?

[Roberta]

Originally Posted by fooferdoggie

should I keep the outside ones out of the bark?

What goes easily into the pot is fine in the bark. Those aerial roots are quite normal. They can sort of form a "bird's nest" - in nature, those capture falling detritus when the plant is growing in cracks in the rocks and roots don't have a lot a place to go. The ones in the pot will be more efficient for picking up moisture, but don't force them to go where they don't want to...

[estación seca]

Even though I looked at the original photos I didn't notice you're growing it mounted until now. Sorry for not paying better attention. This can get big, and fast. If I had mine mounted I would probably dip it in water every day while it's growing.

Mine made 5 new growths last season, but my dog stepped on it and broke off 4 of them. I have it potted in some stuff sold as orchid bark that's closer to potting soil. I have to keep mine almost wet during the growing season or new shoots wilt.

The plant is in a 6" / 15cm pot. The pot is completely full of roots.

[Roberta]

Interesting, I have had far more problem with root rot when too wet than with growth wilt when too dry. They aren't particularly deep-rooted. I agree, mounting is not very practical because of the size factor. I have found that they can be very happy when pot-bound (that's when the "birds nest" roots really take of.