Cattleyas under lights?

[SheilaJ]

I saw that chart in one of my orchid books too - maybe Ortho's All about Orchids. I thought it was weird too and proceeded to completely ignore it.

[Donald]

Let's see. Eighteen hours of light and eight hours of dark.
Hmmmmmmmmmmmmmm!

[Ross]

Originally Posted by entropy82

Ross - what kind of lights, PAR, etc?

I use t5 high output florescents, but light is light. Lumens are lumens, Doesn't matter what kind, what kelvin, what light balance - all those things are for our viewing pleasure (for the most part.) There have been lots of threads here discussing the actual parts of the light spectrum used by plants for blooming and for leaf growth. Most growers don't worry about this and "waste" the remaining spectrum in favor of being able to see the accurate flower color and, perhaps, photographing it.

The original question was about day length, not type of light bulbs. At the equator, one would expect close to 12/12 (day/night) most of year since sun is, theoretically overhead at noon. In winter solstice in northern latitudes near north pole, the daylight nears zero and night nears 24 hours (or so). Not many orchids grow there (or the reverse in southern latitudes - winter solstice). So the question about increasing/decreasing light or day length still remains the same. Light source should never be the issue in this topic. Will certain plants bloom more than once based on changing day-lengths. I contend not! Now we all know Christmas Cactus and some Euphorbia like Poinsettia are sensitive to day/night regimens and might not bloom if outside the accepted range. But for most orchids, I doubt that's the case (at least I have never found it the case.)

[Vanessa]

I also bloom catts under T5 high HOF lights. They get 12 hours all year long with no variation. This works for me.

[nhman]

Based on my experience with blooming over 200 different types of orchids - I would agree with the above. 12 is a good number.
Besides, you can see them in the AM upon awakening and still have light to see them later in the evening after work!!
How sweet is that??

[bodaciousbonsai]

I go with 14 on 12 off during the winter months. T5 x 8 54 watt flowering and growth bulbs. This seems to work for me.

[Ray]

Ross,

Many near-primary unifoliate cattleya hybrids' blooming can be controlled via day-length shortening. Pulling a black cloth over them was the standard way to get prom corsages many moons ago (when they were popular for that).

Now that we are into more-and more complexity, there is a less-strict connection.