Lighting "experts" please respond, the kelvin issue

[calvin_orchidL]

I use mixed bulbs, with no natural sunlight, and things bloom. I believe others only use the higher temperature bulbs and things work as well. There were a few huge discussions on this topic and no one can seem to agree on what is the best combination to use. I have heard that the high/low temperature for growth/flowering is not too applicable to orchids...this belief originates from another type of popular horticultural practice in which flowering is initiated by the change in light temperature as well as duration.

[phearamedusa]

Originally Posted by calvin_orchidL

I use mixed bulbs, with no natural sunlight, and things bloom. I believe others only use the higher temperature bulbs and things work as well. There were a few huge discussions on this topic and no one can seem to agree on what is the best combination to use. I have heard that the high/low temperature for growth/flowering is not too applicable to orchids...this belief originates from another type of popular horticultural practice in which flowering is initiated by the change in light temperature as well as duration.

The reason most growers of the other horticultural group use High Pressure Sodium bulbs has to do with the lumen output these bulbs have vs. Metal Halide. HPS have higher lumen output, and last twice as long as MH bulbs. Some growers will only use HPS bulbs. Flowering is initiated by the change in day night length, not the color spectrum of the bulb. They can flower under MH just the same, but the results are better under the higher red spectrum bulbs. As I stated in my previous post blue spectrum gets you tighter internodes in the growth stage, while red spectrum is more for the blooming stage, but that you could do both under either one with no ill effects to the plant.

For example: Poinsettia are photosensitive plants, in the vegetative state, they are just green plants. Flowering is initiated by them getting 12hrs of light, and 12 hours of absolute darkness, and takes about 6 to 8 weeks of this light cycle, if memory serves me right. If I had two plants exactly the same, one grown under 6400K light, one under 3000K light during the veg state. The one under the 3000K light will appear stretchy in comparison to the one under 6400K. It will make no difference to the flowering of the plants or the quality of the plants.

Sorry for the long post again.
Melanie

[quiltergal]

Originally Posted by calvin_orchidL

I use mixed bulbs, with no natural sunlight, and things bloom. I believe others only use the higher temperature bulbs and things work as well. There were a few huge discussions on this topic and no one can seem to agree on what is the best combination to use. I have heard that the high/low temperature for growth/flowering is not too applicable to orchids...this belief originates from another type of popular horticultural practice in which flowering is initiated by the change in light temperature as well as duration.

Calvin you kill me! Do those bulbs come with complimentary Zig-Zag papers? As you can see Jonny you're not getting much solid science here. However, to my way of thinking personal experience seems in application just as good. My belief is that orchids aren't as picky about the color temperature of their light as some other plants may be as Calvin pointed out. I think you can successfully grow and bloom them under 6500s or 5000s with no noticable difference between the two except for how the flowers appear to your eye.

Here is a picture of my bottom shelf with 2 48" 6500K bulbs. The picture was taken about a month ago.