I hope some of the more experienced people here can help me with these
questions.

I have wide range of varieties in Cattleya, most of them start blooming
in winter as the days get shorter.
I strongly believe that for a lot of those varieties it should be
possible to control when they start to flower by controling the lenght
of the day and night.
So far i found that keeping the plants from flowering can be done with
tubelight or small bulbs.
It can be done by adding extra hours to the natural lenght of the day,
but also to give light in the middle of the night. My question is what
type and intensity of the light would be needed to do so?

regards, Joost

Joost,

If I'm not mistaken, the plants bloom in response to shortened day length,
not to light intensity directly - although I suppose there is a minimum
intensity the plants need to recognize it as "day".

Most of the time catts are forced early by covering them with black cloth to
shorten the daylength, so I'd guess that the flowering could be delayed by
keeping the day long via any sufficiently-intense light source. I suspect
that the closer the light intensity is to that of natural sunlight, the
better.

--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies. Books, Artwork, and lots of Free Info!


"Dogman" wrote in message
ups.com...
I hope some of the more experienced people here can help me with these
questions.

I have wide range of varieties in Cattleya, most of them start blooming
in winter as the days get shorter.
I strongly believe that for a lot of those varieties it should be
possible to control when they start to flower by controling the lenght
of the day and night.
So far i found that keeping the plants from flowering can be done with
tubelight or small bulbs.
It can be done by adding extra hours to the natural lenght of the day,
but also to give light in the middle of the night. My question is what
type and intensity of the light would be needed to do so?

regards, Joost

Ray, Joost,

I've heard several people say you can cause a species Cattleya to skip a
blooming season entirely simply by having a stray light turned on in the
greenhouse overnight or if there is a streetlight shining into the
greenhouse. They are very sensitive to even small amounts of light during
the night.

-Eric in SF
www.orchidphotos.org

"Ray B" wrote in message
news:hfY9h.6079$IW2.3831@trndny03...
Joost,

If I'm not mistaken, the plants bloom in response to shortened day length,
not to light intensity directly - although I suppose there is a minimum
intensity the plants need to recognize it as "day".

Most of the time catts are forced early by covering them with black cloth
to shorten the daylength, so I'd guess that the flowering could be delayed
by keeping the day long via any sufficiently-intense light source. I
suspect that the closer the light intensity is to that of natural
sunlight, the better.

Please see the articles written by Gavino Rotor and Herb Hager at the
OrchidSafari archives: http://www.geocities.com/brassia.geo/OSTA.html

Also note the temperatures at which they flower, and read some of Yin-Tung
Wang's discussion on temperature in control of flowering too, though Wang
primarily discussus Phals. There's a link to his articles at the Archive
page, too.

K Barrett

"Dogman" wrote in message
ups.com...
I hope some of the more experienced people here can help me with these
questions.

I have wide range of varieties in Cattleya, most of them start blooming
in winter as the days get shorter.
I strongly believe that for a lot of those varieties it should be
possible to control when they start to flower by controling the lenght
of the day and night.
So far i found that keeping the plants from flowering can be done with
tubelight or small bulbs.
It can be done by adding extra hours to the natural lenght of the day,
but also to give light in the middle of the night. My question is what
type and intensity of the light would be needed to do so?

regards, Joost

Joost: We have Catts blooming nearly year round. Some follow the calendar
fairly faithfully, others pay no attention whatsoever to it. These latter
bloom whenever their newest growths have matured, and there seems to be
little rhyme or reason, nor do they all bloom at the same time. E.g., Blc.
Carmela's Tropical Beauty -- out of a batch of 100 or so, I almost always
have 1 in bloom, but rarely more than 5-6 at the same time (individual
plants seem to bloom 2-3x/year in a 4" pot, more often as they get bigger).
I have no idea how you would go about forcing or delaying those.

For those on the calendar, I assume that both daylength and temp (and/or
day-night temp differential) all play some role. For these, I think what
you might do to speed up or slow down flowering would depend on what time of
year they "normally" bloom for you. For those which bloom in late summer,
fall and early winter, keeping the daylength longer should slow them down,
shortening it should speed them up, as you mention. But for those which
bloom in late winter, spring and early summer, the reverse should be true.
All within reason, of course. If you start messing with the daylength while
the newest growths are still small, I think you'll do more harm than good.

We have always just let our plants bloom when they want to. I think it's
better for the plants, in the long run. But IF I can figure out how to
concentrate some artificial light on just 1 bench, I may try on one clone
next spring -- I have a big batch of Blc. Merrily Murison 'Megan' which
traditionally blooms in June and July -- when I have no customers :( If I
could get them into fat bud, with a couple open to serve as examples for
Mothers' Day, I could probably sell them. Anyone have an educated guess as
to when I should start, to speed them up by about 6 weeks?

It may be true for some "super-light-sensitive" plants, but I am generally
not a believer in the "stray light bulb" theory (probably not up to the
"minimum intensity" Ray mentioned). We have lights in the nursery; they
aren't very bright, intentionally, just enough to let us get around if we
have to (you'd get eyestrain pretty quickly, trying to read labels by these
lights). We try not to use them -- more because we get the day's work done
between sun-up and sun-down, than because we fear they might interfere with
flowering. The workload doesn't always cooperate, unfortunately. During
shows, I'm often out loading up before dawn, so I have to use the lights,
and I don't notice any significant increase or decrease in flowering during
the following weeks.
--
Kenni Judd
Juno Beach Orchids



"Dogman" wrote in message
ups.com...
I hope some of the more experienced people here can help me with these
questions.

I have wide range of varieties in Cattleya, most of them start blooming
in winter as the days get shorter.
I strongly believe that for a lot of those varieties it should be
possible to control when they start to flower by controling the lenght
of the day and night.
So far i found that keeping the plants from flowering can be done with
tubelight or small bulbs.
It can be done by adding extra hours to the natural lenght of the day,
but also to give light in the middle of the night. My question is what
type and intensity of the light would be needed to do so?

regards, Joost