Yellowing Leaves on D. anosmum in the dead of summer

[cvelez]

So I was looking at my plants and noticed that the leaves at the base of my dendrobium anosmum are starting to yellow. As I understood it, the culture called for lots of light and lots of water. Currently have it in an indoor mini greenhouse, averaging 85% humidity, watering it everyday, next to a south facing window with a grow light coming on early in the morning, turning off during the day, and then on again when the sun starts to set, and air circulation coming from the bottom and circulating down... any ideas as to what's going?

The white balance on my cell phone apparently doesn't exist, so I'm not sure I captured the essence of what's going on. But one of the small leaves on one of the shoots fell off already...

[Roberta]

Is the plant getting light 24 hour a day? If so, I'd suggest letting it have "night"... After all, the plant is from the tropics, where days and nights are pretty equal all year around. I would suggest trying for about 12 hours of light per day. At this time of year, if you have a little shade outside to protect from direct noonday sun (which can toast leaves of even the toughest orchid) , it actually might be happier outside (and a whole lot less trouble) I suspect that you have plenty of humidity outdoors...

[cvelez]

The light turns off at night. Living in Texas, the humidity ranges from 30-40 when it hasn't rained for a while and temperatures rise up to over 100 sometimes...

[nogreenthumbs]

I'm not saying that this is the problem, but...

If it's in a South facing window in SA, TX this time of year, I can't imagine that you'd need any additional light.

[Roberta]

Originally Posted by cvelez

The light turns off at night. Living in Texas, the humidity ranges from 30-40 when it hasn't rained for a while and temperatures rise up to over 100 sometimes...

Then raising the humidity is not a bad idea, though if you water enough, outside low humidity probably won't hurt it. Heat is not much of a problem... after all, it is native to some very warm parts of the world - Philippines, Indonesia, much of lowlands SE Asia. Humidity there is higher, but temps are just as high... a good bath in the evening and morning should give it the hydration it needs if it's outside. Then you get the benefit of natural air movement and the full sunlight spectrum. Out of curiosity, what is the temperature in the "mini greenhouse"? If it is NOT pretty toasty (a lot warmer than would be comfortable for a person), it may think that fall has arrived.

[cvelez]

It ranges from 75 to 80 during the day...

[Roberta]

Originally Posted by cvelez

It ranges from 75 to 80 during the day...

That's on the cool side for this particular species. Outdoors at this point might be too severe, however... next year perhaps consider moving out in the spring so that it can acclimate. But I don't think the leaf drop indicates a serious problem, just a little less than ideal conditions. To get it to bloom, giving it the diurnal range (temp difference between day and night) in winter that it wants may be a challenge.

[estación seca]

That's more a bract than a leaf. It happens to all bracts as growths mature. I wouldn't worry about it.

I agree you could probably grow this plant outside almost all year in bright to dappled shade. Mine has experienced 100+ F / 38C days without any problems. You would need to water plentifully during hot weather. I bring my plant inside during our summer heat, and put it outside when nights are cooling. I leave it out all winter except on frosty nights. I bring it in when days start getting hot.

I don't recall whether San Antonio gets frost. This plant can tolerate temperatures all the way down to freezing, and some people say a few degrees below.

[Roberta]

Originally Posted by estación seca

This plant can tolerate temperatures all the way down to freezing, and some people say a few degrees below.

It needs to dry out in winter anyway... when it's dry, it can tolerate quite a bit of cold. And a cool, dry jolt is really necessary to initiate blooming, I think. Since it has been indoors all this time, probably not a good idea to blast it with sudden heat at this point (it would be fine if it gets to gradually build up to summer). But once it starts to cool off a bit in the fall, putting it outside until night temps are down into the low 40's F may get it thinking about spring flowers.

[cvelez]

Originally Posted by Roberta

once it starts to cool off a bit in the fall, putting it outside until night temps are down into the low 40's F may get it thinking about spring flowers.

I think I'll do that and then let it stay outside in the summer next year