Question
QUESTION: Oh, thank you, thank you for being available for questions.  A year and a half ago, a friend gave me 4 orchid meristem clones that he had bought in Singapore.  He left them in the little plastic tubes for A YEAR (!) before he gave them to me.  I planted them in Ortho orchid mix in plastic pots and put them outside under a big tree.  They were in a dish with pebbles and water.  Did fine.  I brought them indoors and put them under a Floralite bulb for the winter.  Did fine.  I water them every week with half strength Schultz orchid food.  

Now for the difficult part.  The Oncidium, Dendrobium and Catteleya are OK, have huge roots and are putting on big leaves.  The Vanda, however, is the problem.  Hasn抰 grown at all, but is still alive.  Someone suggested putting them in full sun, so I put them in a bright east window, getting sunlight from sunrise till about noon.  I have huge pots of blooming geraniums (pelargoniums), poinsettias and begonias in that window, so it抯 very bright.  All the orchids started to turn yellow and some developed brown spots, so back under the light they went.  The Ortho book says Vandas need about 3,000 foot candles (which is what it got in the window), but that was not a great idea, based on the plant抯 response.  Under the light, it gets about 700 foot candles, and the other orchids like that also.  

So, my question is, can I fix the Vanda, am I doing the right things?  I know that plants are intuitive, but as a scientist, I need some measurements as well.  I should mention that I have a large number of plants and trees in my house, including bromeliads, pineapples that I grew from grocery fruit, hibiscus trees, so I抦 not new to houseplants, only orchids.

Thanks for your help.

Florence
PS, sorry for the long post.


ANSWER: Hello Florence,

No problem with the long post, the more information you can give me the easier (?) it is for me to determine what the problem(s) might be.  

Vandas by nature crave high light levels, so if you have a southern exposure window, that could be a better spot for it but keep it about 3 feet from the window.  You didn't mention if it was in a pot but I got the feeling it is.  If it is, keep the potting mix moist but not constantly wet, vandas love moisture but need a slight drying off between waterings.  Also, if possible, mist the upper parts of the vanda using a spray bottle filled with water and a little fertilizer.  Temperatures above 60F is preferred (above 70F and it will be very happy) along with humidity above 50% and some light air movement.  To tell if it is receiving good light exposure, look at the leaves which should be a light to medium green color, dark green would indicate not enough light.  

If the other orchid leaves started to turn yellow and developed brown spots, it may be that the potting mix is breaking down and will need replacement in the spring.  Brown spots on the leaves could be botrytis, a fungus, possibly caused by water left of the leafs overnight.  Any watering and misting of orchids should be done in the morning to allow sufficient time for the water to evaporate before nightfall.  As for watering them, wait until the potting mix becomes barely moist before watering them again.  

I would suggest moving the cattleya close to the vanda as cattleyas love bright light too but not as much as vandas.  The oncidium and dendrobium need bright indirect sunlight with maybe a few hours of direct early morning or late afternoon sunlight.  Temperature wise they all like 60F to 85F.  

Hope this helped.  Write back if you have additional questions or would like more information about the above.

Jim Kawasaki
San Jose, Ca.



---------- FOLLOW-UP ----------

QUESTION: Thanks very much for your answer.  These orchids are tiny!  Even the biggest one has leaves of only 3 inches, and the Vanda leaves are about an inch and a half. Considering that they were all under an inch when I uncorked the plastic tubes, they are growing.  My feeling is that the yellow leaves/brown spots were caused by the sunight.  They looked OK under the light, but started to change about a week after I put them in the sun. The potting mix is intact.  Two days ago, I put the Vanda in a small wooden box (4" x 2") inside a small glass ball aquarium, hoping to increase the humidity.  I put a few chunks of orchid mix in the box to hold the orchid stable.  Do you think that baby orchids need less light until they are larger?  If you could give me some light intensity measurements (foot-candles or lux) I could make sure they're in a good spot.

Thanks again,
Florence

Answer
Hello again Florence,

If you moved them directly from the plastic tubes into pots then directly into bright sunlight, what may have happened is the leafs got sunburned.  Although vandas do need quite a bit of bright sunlight, it is best to gradually move them towards the light over weeks to minimize the potential for leaf burn.  

You probably do not need the small wooden box within the glass ball aquarium, just place the vanda in with just an inch or so of moist bark pieces, add water as needed to keep them moist.  To keep it upright, tie a string on it and hang it from a stick or wire laid across the opening.  To help minimize evaporation, you can try putting a cover with several one inch holes in it on top.  I heard of a person who placed an inverted glass aquarium like yours over his orchid, lifting it off once or twice a week for an hour or so and it bloomed fine.

Afraid I'm not into measuring much of anything but what I can tell you is when I say bright indirect light I mean place your hand about 12 inches over the orchid and if there is no shadow or just a very faint one, that is about right.  What some other growers more scientific than I talk light intensity for vandas, they mention a minimum of 3,000 foot-candles.  

Lastly, you are correct that most baby orchids do not require as much light as adult orchids.  Any where from half to three quarter the light intensity with a very gradual transition into brighter light.  

Jim Kawasaki
San Jose, Ca.