Too much sun

[swamprad]

So what I am doing is trying to grow vandas, cats, bulbos, paphs, phals, and a whole lot of other stuff in one greenhouse. The idea is that the high light stuff is hanging and shading the low light stuff. Well, it's not working very well. Many of my paphs are yellow. I hate yellow. Not burned but yellow. I have 50% aluminet shadecloth on the ghouse, but that is apparently not sufficient. So today I rigged up some more shade cloth over internal structure to shade part of my paphs, I think that is good. I traded places with some phrags and paphs to a shadier spot. I rearranged some of the hanging high light plants to provide more shade. And I might rig up some more shade cloth draped over some of the paphs, so I think I've got it under control. That's the situation, here is what I'd like feedback on:

How long until the yellow leaves turn green again? Or will they ever? Will more nitrogen hasten the process? The yellow leaves are just making me sick.

The brachies, most of which are from Nick Tanacci (one of which I got an AM on a couple months ago, my first AOS award, yay!) are not yellow. Well, a couple of them are, but mostly not. Don't those guys like lots of light? Don't they grow on rocks in full sun in nature? I am thinking of leaving them in the high light area.

Growing under lights was so much simpler! Never had yellow leaves! But they do grow so much better in a greenhouse, growing pains I guess. And as an aside, my Dollgoldi is in bud! And today I noticed that some devil from hell had taken a bite out of the side of the bud. What a disappointment, oy.

 

[SlipperFan]

Probably a dumb question, but are you sure the yellow leaves are from too much light? Are all the leaves of a given plant yellow, or just the bottom or top ones?

If it is indeed too much light, you should see a change back to green within a couple of weeks.

 

[goldenrose]

hmmm the 2 InCharm Handels I got from Ernie are slightly yellowing, there's a case of lights to GH!
Don't know about the brachys being in full sun, but bright they sould be able to handle. Definitely in winter could handle more light.

 

[likespaphs]

i'm not sure if giving it a dose of epsom salts would speed the process

 

[Ernie]

Mark,

Keep an eye on temp there in Memphis! Yellow can turn to crispy brown if temps get too hot. I wouldn't really sweat it as long as you keep things in check. If you apply more shade, they should darken pretty quickly (weeks not days).

 

[NYEric]

Good luck. Sorry about your Dollgoldi bud.

 

[fibre]

All my brachys like to get direkt sun on a S/SO windowsill. Only in the middle of the summer they get a little shade on high noon from a roof above the window.
If your plants come from conditions under lights, I think it will be hard to get them established in a greenhouse with nearly no shade. My experience is: the elder growths will never really adept, but the new growths will better get along with brighter conditions. And if one leave is burned by sun, not only a little bit yellow, it will never be healthy again.

 

[Rick]

Mark

Your lighting/shading is very similar to mine, and you are at about the same latitude as me (Nashville versus Memphis, TN), and I'm not getting the yellowing. You are running a bit hotter outdoors, so what are your greenhouse temps? Despite running near 100 every day in Nashville, I've been able to keep my GH in the high 80s/low 90s during the day.

You have a lot of multis and multi hybrids in your collection that should have no problem with bright light, so are they having yellowing problems too, or just low light maude or barbata types?

In general phaleanopsis are consistently lower light plants than paphs, so are those yellowing too? If not then I would not suspect excess light is your problem, though I wouldn't rule out excess heat and low humidity. You may have to turn on that big noisy ventilator fan.

The Memphis water is way softer and lower pH than Nashville water, and pretty devoid in calcium and magnesium (maybe K too) You may have a mineral imbalance going on that may be pointing to a calcium/magnesium shortage rather than a light problem.

What's going on over at Charle's GH? His GH is more directly exposed than yours, but I don't know what kind of shade cloth he's using. Both Charles and I have much smaller GH's than yours, but use the same strategy to hang lots of plants to shade lower plants. Yup finding those sweet spots for different plants is what makes green house gardening exciting.