Dendrobium Leaves - Orchid Board

Alan Sailer · #1 09-07-2021, 12:52 PM

I am am pretty new to orchids but have been happy with my successes. A half dozen phalaenopsis have been doing well for me over the past three years.

I have a single dendrobium which has bloomed twice since I bought it. After the last bloom another stem started growing. It reached about six inches with about six leaves, all a healthy green.

Two weeks ago the plant started blooming again. From an older stem. What I don't understand is that all the leaves on the new stem have yellowed and fallen off. What's that all about?

The plant is indoors, LED lighting and is soaked once a week, the same as my phalaeniopsis plants.

Thanks for any reply's.

Cheers.

estación seca · #2 09-07-2021, 01:41 PM

Welcome to the Orchid Board!

Dendrobiums naturally occur over a huge part of the Earth, from Japan throughout eastern and southern Asia into Australia. There are many different kinds from different climates, with different growth requirements. Does your have a label with a name, or can you provide a photo?

In general once a week during the growing season might not be enough for most Dendrobiums. They are heavy water users while making new growths. But there are other things that might cause the leaf drop. Photos would help.

Some people can't post photos until they've made 5 posts. If you reply to this one that will be two for you. You can go to other threads and make replies there as well to get yourself to 5 posts.

Roberta · #3 09-07-2021, 02:21 PM

Many Dendrobiums bloom on bare canes. Some ONLY bloom on bare canes that have lost their leaves. So no worries there.

Alan Sailer · #4 09-07-2021, 02:27 PM

Thanks for the reply's.

I will try and get a picture up. After I meet the six post limit. As far as the water, maybe the "stress" of blooming highlighted the under-watering? The plant was growing well until the bloom.

Interesting about the bare canes. The bloom is from the oldest cane which has four leaves. The newest cane is the one turning yellow.

I may have been able to attach a photo. The newest cane is at the front of the image. The other cane has always been yellow but seems to be getting worse. And the third cane is great green and blooming.

Cheers.

Roberta · #5 09-07-2021, 02:57 PM

It is very likely that you could post pictures now... I have see quite a few instances of very new members who were able to post pictures using the "Manage Attachments" function in the Go Advanced screen for posting replies.

---------- Post added at 11:57 AM ---------- Previous post was at 11:29 AM ----------

Thanks for the photo! The plant looks good. Questions come to mind, though, looking at the photo. Does the decorative pot have a hole at the bottom? If not, you need to get the plant out of it. If it does have drainage, not as urgent, but the medium appears to be on the old side. If you haven't repotted it since you bought it, it's a candidate... The ideal time to repot is when you see new roots - even if it is blooming. If the mix is badly broken down, you're better off repotting, in the hopes that a better environment will inspire new root growth. But a healthy orchid is all about roots - if those go bad due to bad medium, the plant will decline. If you repot, just remove and rinse off the medium that comes off easily. Don't worry about getting every last bit, which will likely damage roots. A bit of old medium left behind won't harm.

Alan Sailer · #6 09-07-2021, 03:22 PM

Roberta,

It is about three years old (from time pf purchase). And I have not re-potted. The drainage is excellent, lots of holes. One white root is peeking over the edge.

If you strongly suggest re-potting during blooming I'll do that. Standard mix, orchid mix and bark?

Thanks for the help.

Cheers.

Roberta · #7 09-07-2021, 03:45 PM

If there is evidence of new roots starting (just little green tips peeking out) then go ahead and repot. It won't hurt if you wait a bit to let it finish blooming. But it definitely wants repot fairly soon. I don't know what is in the "standard mix" or "orchid mix" ... you need a well-draining mix, personally I would use medium bark with some fairly large perlite (Not the powdery stuff that is used for soil) or pumice or lava rock. (If you don't have access to any of those additives that just help keep the mix open , plain old bark works fine) Dendrobiums typically need to get almost dry before watering again, and need air around the roots.

Shadeflower · #8 09-07-2021, 04:17 PM

This is like my dendrobium although yours is white.

They are warm growing phals, they do not like temps under 20 degrees C, can handle 18C lowest.

But this looks like the roots have gone bad and more serious than wrong temps. you need to see what is going on in the pot. It looks too soggy. So either the mix retains too much water or you have possibly been overwatering but you better check the roots.

Alan Sailer · #9 09-07-2021, 04:36 PM

Great. I've gotten exactly what I want. Hopefully I can get this thing thriving. It's always just looked hanging in there.

The phal... are all thriving so I am not hopeless as an orchid person.

Cheers.

Roberta · #10 09-07-2021, 04:44 PM

You are doing fine! In fact, that Dendrobium (called phalaenopsis-type Dendrobium or Den- phal though it is not related to Phalaenopsis at all) actually likes some of the same conditions as Phalaenopsis - especially warm temperatures and air around the roots. The biggest difference is that the Dendrobium needs quite a bit more light than the Phalaenopsis.