Dendrobium leaves are turning yellow and fall off

[Alya091]

Hello guys,

So, i bought this dendrobium on 29 August and repotted it the next day with Seramis Spezial-Substrat für Orchideen Mix and add a light layer of spaghnum moos on the top layer. Until now i haven't gave it fertilizer except twice weekly sprays with Growth Technology Orchid Myst Spray (as with my other orchids). I put the Orchid inside my room on a east-facing windowsill. Lately (since around two weeks ago) the leaves started turning yellow and fall off and continues to do so until now and now some of the canes/pseudobulb doesn't have any leaves left. Did i do anything wrong? is it the wrong Substrate? (cause my 3 other phalaenopsis orchids didn't seem to have any problem with the Substrate) or is it a cold damage? The weather here in kassel rains quit alot or could get cloudy/misty the whole day. I'm pretty sure this is not a dendrobium nobile either, so it couldn't be a winter resting period, could it?

Any thoughts and advices would be greatly appreciated!
Alya

[estación seca]

This is probably a Dendrobium phalaenopsis hybrid. They prefer even warmth and watering all year, above 15C, with maybe a little less water in winter. They prefer brighter light than Phalaenopsis.

Their leaves drop like this from being too cool, not getting enough water or spider mite attack. What is the temperature in your growing area?

The time to repot is when just beginning new roots. If not making new roots the older ones may be damaged and the plant may have trouble taking up water.

[rbarata]

Seems to be a Den Phal. Never had any of these but I think they are deciduous too.
Let's see what others say.

[Roberta]

Den Phal-types aren't deciduous... so if they drop their leaves, they're not getting something that they need, or getting something they don't need (like cold)

[rbarata]

Originally Posted by Roberta

Den Phal-types aren't deciduous... so if they drop their leaves, they're not getting something that they need, or getting something they don't need (like cold)

Always learning!

[Roberta]

Originally Posted by rbarata

Always learning!

I don't grow Den-phals either... because I can't give them the conditions they need (warmth and bright light), too many other things that do well for me.

[rbarata]

Den Phals, don't know why, don't appeal me.

[Alya091]

hmmm...i don't really know what Temperature in my room is but if I look in the weather app today is 14° normally is a bit higher than 14°. Today is cloudy again probs thats why

[Dusty Ol' Man]

The leaves in question (from the photo) appear to be on an old, if not the oldest, cane. My den/phal will drop leaves on the oldest of the canes as the newer ones grow stronger. They have gotten longer and fatter with each successive new growth.
I keep mine outside under a 50% shadecloth all year, except when the temp drops below 50F. Then it comes inside to sit in front of the glass door it sits outside of the rest of the year.
My local temps in the summer are 90+F day/70+F nights. RH is generally 75% or higher most of the time.

[estación seca]

The leaf drop is definitely not from cloudy weather. This kind of Dendrobium normally keeps leaves on stems for at least 2-3 years, and often more. Moving from a warm area to a cool area can cause leaf drop like this. Inadequate water can as well.