Is my Dendrobium getting too much light?

[Buttercup]

Hi there!
I am new to orchids but completely entranced after my husband bought me a phalenopsis for my birthday. About a month ago I bought a dendrobium thongchai gold from a reputable dealer in San Diego. I have a very sunny South West window in a bedroom upstairs and originally had this in there. In about two weeks I noticed the biggest leaf looked strange. It had a dark green looking spot. The next day the leaf was yellow so I tore it off. I have read that yellow leaves are a sign of sumburn (a dark brown spot also showed up the next day). I moved the den. downstairs to a less sunny window (still south west but with the overhang from the roof). The biggest leaf on the biggest cane has now turned yellow. I'm so confused. The leaves on the littler canes look fine. Also, the buds are all in good shape and about 4 have opened. Adding to my confusion, I have my phalenopsis in this window but every book I read says they need waaay less light (but this plant is doing great!). Ahhh. I have never posted anything but tried to post a picture. I called it "yellow dendrobium" hopefully it works?
~A novice looking for advice

[Ellen]

Your dendrobium may just be a little stressed from the move. Are the leaves that turned yellow and brown older, lower leaves? If so, I wouldn't worry. I doubt that your plant is sunburned. Just give it time to get used to the new conditions.

[Buttercup]

Hi Ellen,
So far 3 of the leaves have done this. 2 of them have been the biggest leaves on the biggest cane. 1 was the biggest leaf on the second biggest cane. All were towards the bottom. Do you think I should move it back up to the more sunny spot? Thanks! Also, after all the flowers on the big cane flower, do I just cut the stem back to the first node or is there a special procedure since this plant has canes?

[Cynthia, Prescott, AZ]

Old flower spikes can be cut off (use a sterilized tool, don't use alcohol), but don't cut off any canes. It is not important what the size of the canes are, but how old they are. The newest growth is zero years old, and if you follow the chain of connection backwards, each successive growth back is another year older. So the oldest canes will loose leaves, and newer canes this time of year will lose some of their lower leaves. Sun burn always has the pattern that the part of the leaf facing most towards the sun will have the color change, and it usually is in the form of a single large spot, definitely not the whole leaf. My guess is that the leaf loss is normal, and the plant will probably do better with more light, but feel the leaves when the sun shines to avoid sunburn. Warm to the touch is OK, or a little warmer, but not hot to the touch. As the seasons change you will eventually have a problem and probably will need a filmy curtain to shade the plant a little.

[jerrymeola]

This is a good time to explain sunburn better.

Your plant does not sound like sunburn. Sunburn will usually be on the upper-most leaves. Lower leaves are dying from old age. Sunburn will develop where the suns heat can build up, this is usually the point where the leave bends. On an Oncidium alliance plant this is always the case. On a den the leaves do not bend noticeably.

I grow my dens outside under 50% shade cloth in SW Florida. Probably 3-4 times the light level of your window (and twice the recommended level). Dens do not burn easily.

The last point applies to more then just burn. Hobbyist need to learn that the short answer in this and any forum or advice from a dealer, is not the only possibility only the most common.

If it was really burn the burn area would have turned light brown, the burn area would have shrunk very thin on a Den compared to the rest of the leaf, and it would not have fallen off. Burned leaves look bad but never kill the plant or the leaf. The unburned area is still as good for the plant as any other leaf.

The good and bad news is the same. Dens often loss a lot of leaves especially after being brought home the first time. The recover and do just fine. Relax a little and enjoy the plant.

[Buttercup]

This is very helpful to me. I honestly jumped to the first conclusion that I have done something wrong! Thank you for your help. I have one last question. Will canes grow new leaves or once they lose them will they not re-grow?

Canes will not grow new leaves, but they may bloom again.

[Buttercup]

I just wanted to say thank you for the advice here. Since I stopped panicking that I was doing something wrong, no new yellow leaves (or brown spots) have appeared. I guess it was just the plant getting used to everything. Now almost all the buds have opened and I love it.