growing under artifical lights

[cnarciso]

Hey guys. I recently joined here to ask a few questions about growing orchids under artifical lights. I have recently gotten involved with paphs and purchased a few complex hybrids from a local dealer. Since I was having problems controlling disease on my orchids grown outdoors, I decided to try and do these inside under lights. I purchased two shop light fixtures and alternated cool (daylight, 3100 lumens, 6500K) tubes with warm (yellow, 3400 lumens, 3000K) tubes. All tubes are standard 40W. There are a total of four tubes which hang approximately 6 inches above the plants on a PVC-rig I whipped up out of some scraps. I have read online that paphs grow nicely under 4 flourescent tubes of these color temperatures to give both the blue and red spectrum necessary for adequate growth and blooming. However when I take light measurements around the plants I barely read 500 footcandles. Most sources say paphs need at least 800-1500 footcandles to grow successfully. My question is, are these conditions ok for paphs? The setup I created looks very similar to others I have seen/read about online and which people say they have had success with; still, 500 footcandles seems really low. At the same time though, I have had the plants about 1 month and they look healthy, with leaves of appropriate color.

[John D.]

I use a very similar set up and my plants are doing well, for some paphs almost too much light. You can add more hours with the lights on if they need more light. It will make up for lower intensity.

[cnarciso]

Thanks for the reassurance John. If I might inquire, what is your lighting schedule? I currently have mine timed for 14 hours per day from 6:00am - 8:00pm.

[VermontOrchid]

I keep my orchid lights on 18 hrs

[VermontOrchid]

I like to keep my orchid lights on 18 hrs a day.... if that helps...

[cnarciso]

Thanks. I had mine set for 14, but I bumped them up to 16. I shall probably slowly reduce down to 12 for the coming winter.

[stefpix]

Why bump down for the winter? actually you may need more. If you grow orchids that originate in the tropics it is usually about 12 day / 12 night hours all year around . You may need more light in the winter because you get less natural light from the windows...

[RosieC]

I think you are right Help for orchids from the tropics, but many orchid do need a winter rest period and probably expect less light so if you have artificial light you are in danger of them not getting their much needed rest unless you conciously adjust it.

[stefpix]

Rosie
I think the light difference for what grows in the tropics is negligible. Actually some that grow at high altitudes in the tropics may get more light in the winter if they grow on deciduous trees, since there are no leaves to provide shade. Probably the winter rest has more to do with watering than light. There is a dry seasom and a wet season, so teh winter has very little rain [yet the humidity may be high].
The UK I remember has pretty extreme differences in day length between winter and summer.

But even in Miami the difference between the longest day and the shortest day is almost minimal.

I wonder if some member from the tropics can chime in.
I was in Haiti less than 2 years ago. it was the end of september. Sun was from 6 am to 6 pm more or less.

Also in the tropics in the summer [even in Miami] you get almost daily storms with very dark clouds blocking the sun for a few hours most afternoons.

I hope i do not sound pedantic, but I am just thinking plants from teh tropics are not used to shorter winter days. Then 2 hour difference of a few fluorescent tubes may be negligible. maybe equivalent to 15 / 20 / 30 min of sunlight.

[RosieC]

My point really is that not all orchids are FROM the tropics. Some are European, some are from Australia... they come from all arround the world.

Yes, orchids which originate in the tropics probably don't need a seasonal change in light, but you can't assume all orchids are like that.