Hi everyone,
I'm having some problems with two of my dendrobiums. As some of you know, I really enjoy growing the formosae/nigrohirsute dendrobiums. It's now my 2nd season growing them, and while I'm getting fatter/taller canes compared to previous years, I'm also noticing some strange leaf yellowing problems. I've noticed with dendrobiums in general that the 'normal' leaf drop occurs by which the entire leaf turns yellow, then dries and drops off. However, what I am observing is a yellowing from the tips, followed by a drying, that progresses from the tip down to the base of each leaf. This also commences from the bottom of the cane up.
No rot, just yellowing and drying. I fertilize way too infrequently for this to be fertilizer burn. Regardless, below are my conditions and some photos...I'm really hoping someone out there can help me out. These are two of my favorite plants so I'd appreciate any feedback whatsoever.
Plants in question: formosae dendrobiums
Dend Peng Seng (tobaense x cruentum)
Dend Frosty Dawn (dawn maree x lime frost)
Conditions:
8" from T5 lights, 16 hrs a day
Grown in a tank with higher than ambient humidity (vague, yes I know)
75-85F
Potted in 3" plastic pots with course fast draining coconut chunks, charcoal, and hydroton pellets.
Watered once every 3-4 days, media is allowed to NEARLY get dry in between watering. (at the beginning of the summer, I let them get bone dry for a day in between waterings...that was when I started seeing the yellowing, so I upped the watering schedule...but the symptoms are still progressing)
Plant conditions:
In general, roots seem very robust - both plants have tons of roots, growing both into the pot and out of it. All roots have green tips, all look white and healthy. Both are quite root bound, to the point where I could risk some damage if I were to unpot them. It does concern me a little that there is little to no root growth out of the holes at the bottoms of the pots...nor can I see many roots through the holes at the bottom.
This is the plant today - it's been in bloom 2nd season now, for 3 months, on the second cane. It is currently maturing another cane which I believe is near to mature. You can see the severe dying back of the leaves...originally I attributed this to a natural annual leaf drop. However...
the newest cane is now showing some leaf tip yellowing which scares me.
This is Frosty Dawn...started showing the yellow leaf tips about a month ago.
Lots of roots all over the place. Some roots look like they stalled and then came back to life...not sure why.
The new growth on the frosty dawn...lagging behind the peng seng but it looks good so far. You can see both what I suspect is a natural leaf drop (the entire leaf is yellow) as well as the strange leaf tip yellowing in the background.
I'm not sure if humidity is an issue...I suspect not, because I have a dawn maree which is a parent of frosty dawn, and it's growing happily on my windowsill with no yellowing at all.
Any ideas? I've exhausted all my options so I'd really appreciate any leads.
Problems with formosae dendrobiums - yellowing leaf tips
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