I can tell you first hand that when I left the lights on 24hrs a day ( my
living room) , I didn't see any flowers on my paphs last year, but the
previous year normal activity with an old timer.

put the lights on a timer, I now turn all lights off at night and have seen
many spikes started

--
Diane



"Susan Erickson" wrote in message
...
On Sat, 01 Jan 2005 23:08:21 GMT, Xi Wang
wrote:

Just curious, and perhaps I've missed this in past posts, but if one
grows orchids with artificial lighting, can this light be sustained day
and night (or the majority of a 24 hour period anyway), or do plants
have some sort of circadian rhythm that needs to be maintained, i.e.
needs period of darkness for proper growth?

Cheers and happy new year,
Xi

One of our speakers said she moved from a Gulf coast Texas gh to
under lights in Golden CO. She said she had to leave the lights
on 18-22 hrs to get the same light effect to the plants. This
was short term until she got her gh built here.
On the other hand I had always heard anything much over 12 hours
was a waste.
SuE
http://orchids.legolas.org/gallery/albums.php