sick dendrobuim
 

Good day everyone

I have recently purchased 2 dendrobuims and they were looking good, but they were planted in a very soggy medium that looked like coconut fibre (not sure)

after a month i repotted them in a bark orchid mix as with all my dendrobiums, but now they started going yellow
I have no idea what possibly could be wrong
The only thing i can think is maybe because its the start of our winter season - any help please

Dendrobium is very sensitive to repotting, the plant does not like to disturb its roots.
The optimum repotting period is when start to grow new roots. The plant has no roots anymore, they all died. Still has a chance to survive.
You put the plant in a clay pot (no media) and if you have good humidity, forget it until spring. There is a possibility that the plant will make keiky.

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Or, let the plant where it is (in the actual pot) and forget about it until spring.
This plant, as long as it has no roots, no longer needs water.

Thank you for the reply, humidity is a bit of a problem this time of year, but i will keep it as humid as i can for the winter period

Possibly, you could put the plant (with no media) in a plastic bag with just a bid of wet spaghnum moss for moisture. (Sphag and bag) Keep the plant in indirect light (so that it doesn't toast) You can occasionally open the bag to exchange the air, but until it starts growing, it's the humidity that you are after.

Thank you very much i will do the spag and bag

I personally don't think it's necessary to do a Sphag and bag for such a large orchid. I'd just leave it alone and put it in a moderately warm location with moderately bright indirect light. Water extremely sparingly during the winter, (like once every 2 - 3 weeks), and wait for spring to roll around.

I'm gonna be straight up...

There's a possibility you could be tempted to water this orchid of yours a lot to try to "help it". Resist that temptation. It is going to be very difficult to if you run into these feelings, but just keep to the plan of watering only once every 2 - 3 weeks. By spring, you might see more glimmers of hope from this plant.

Try to do too much, and it could speed up its demise.

Use large grade bark, and use a smaller pot with slots or holes for air circulation to the roots.

When summer rolls around, water only once a week.

I think there's a fair chance it'll make it or it could make a keiki.

Lucky for you, some Dendrobiums have their roots die back during dormancy anyways. If yours is one of those, you don't need to worry too much.

The issue is one of humidity... if the climate is very dry and this is a type that likes it more damp, it may need a bit of help. Looking at the photo, I suspect a phalaenopsis-type Den, which doesn't want a dry rest. So it's a wild guess as to what it needs... knowing the type would help

Actually, Den phalaenopsis, the species, does have a winter dormancy, but it is light. Most people do not observe it in cultivation.

It is an epiphyte or lithophyte.

There are sources that mention the dormancy and the mode of growing. It is not necessary to take my word for this. One of the sources is Dendrobium and Its Relatives by Bill Lavarack, Geoff Stocker, Peter S. Lavarack, and Wayne Harris.

The species comes from Queensland, Australia to Papua New Guinea.

Humidity does not have to be too high for Den phalaenopsis. As long as it is moderately humid, it should be ok.

As mentioned, the plant should be kept humid, this I do agree with you on, but I don't think that Sphag and bag is necessary.

I probably just forgot to mention the humidity portion of it in the previous post.

It is true, we don't really know what kind of Dendrobium it is. Maybe if the OP can say what kind of hybrid it is, it'd be helpful.

Good day sorry for the late reply

I did attach a photo from the internet of the flower
hope this will help with the i.d. they are 2 both look the same except for the colour, the other one is off white with a pastel pink lip

Regards

They are Dendrobium phalanopsis. Den phals. Some of the leaf dropping could be natural. They grow canes, bloom on that cane and older canes. A few years later, they shed their leaves. These leafless canes while ugly, still bloom and feed the plant. Intermediate temps and light, like we would be comfortable in. I grow in clay and bark and water 2x a week, more or less by the weight of the pot and if it is the growing season or winter. You'll develope a feel for that. They like pots on the smallish side. Did we establish that get have any roots or not?

I would re read Phillip's advise and follow that. I think this is part of their normal growth cycle.