yellowing on my dendrobium's leaves

[Origamifan]

Hello
I was given a dendrobium last week by my parents. I got it in a pot with compost as the potting medium.
I repotted him first chance I got with orchid compost (bark) and the next day watered him.
He was a healthy green when I got him.
And now I can see he's got yellowing on his lower leaves and seems a less vibrant shade of green all together.
His stem also seems to be getting darker.
See attached photos

What do I do?
Was I wrong to repot or is this a disease or stress?

[Swimmingorchids]

hard to say. First of all who put the plant in compost?

It's unlikely the shop will have done it. A lot of times dendrobium are sold in coco coir which looks a lot like compost but it isn't.

Coco coir is 100% hydroponic - bark is not. Might not seem too important but it actually is because if you switch any plant from hydroponic to another medium it will get stressed and lose roots.

I can't tell what your plant is suffering from but the bark you have it in now doesn't look that great either but hard to tell from pictures.

If the roots are rotting you need to stop the rot first - then it will be a slow recovery game to see if it develops new roots.

Roots should be white, grey or green, never black or brown

[rbarata]

What do you mean by compost?
That's a nobile type dendrobium it needs a medium with good drainage: for ex, a mix of bark+leca mixed with perlite to retain some humidity.
Everything else probably will kill the plant.

[Origamifan]

Originally Posted by rbarata

What do you mean by compost?
That's a nobile type dendrobium it needs a medium with good drainage: for ex, a mix of bark+leca mixed with perlite to retain some humidity.
Everything else probably will kill the plant.

Compost was standard soil compost for plants like geriums.
Thanks for the ID!

---------- Post added at 04:07 PM ---------- Previous post was at 04:06 PM ----------

Originally Posted by Swimmingorchids

hard to say. First of all who put the plant in compost?

It's unlikely the shop will have done it. A lot of times dendrobium are sold in coco coir which looks a lot like compost but it isn't.

Coco coir is 100% hydroponic - bark is not. Might not seem too important but it actually is because if you switch any plant from hydroponic to another medium it will get stressed and lose roots.

I can't tell what your plant is suffering from but the bark you have it in now doesn't look that great either but hard to tell from pictures.

If the roots are rotting you need to stop the rot first - then it will be a slow recovery game to see if it develops new roots.

Roots should be white, grey or green, never black or brown

My mum did. Thanks for the advice

[Swimmingorchids]

not sure why they hate soil so much but it is what it is. Tbh from all I know it should recover with the right care and attention

[rbarata]

Epiphyt orchids, like this one is, grow with their roots exposed to the air. They get rain and dry relatively fast after that. They are also used by the plant for photosyntesis purposes.
If you use compost or soil you won't allow fresh air to flow inside the medium. That's why you need a type of medium that allows air to circulate.

[Ray]

The yellow on the one leaf looks like sunburn. Nothing you can do now, so don't worry about it.

Epiphytes do much of their respiratory gas exchange through their roots, rather than leaves, so - as has been said above - it is important that they have lots of air flow around them. Soil, or even too fine of an orchid potting medium, will trap water in the spaces between the particles, cutting off that air flow and suffocating the roots.