Darkness needed for Phals?

[boxerfan]

I think my phals are getting enough light during the day, but I am wondering about how much darkness they need at night. We typically leave a light on at night in our den which ajoins the dining room where the orchids live. It is not a very bright light, but I don't want to upset the orchids' night time rituals. My partner thinks I'm abit nuts. Oh BTW and off topic, I have plans to go with a friend to the Carter & Holmes Orchid Nursery this Friday. TIA, Lisa

[Sharyn]

boxerfan: I think I read somewhere that some orchids don't like any light at night, however, I refuse to live in the dark so they get whatever light is on at the time, usually not a very bright light. It hasn't affected my phals at all.

Check out the free classes at Carter & Holmes while you're there. Wish I lived closer, I'd go with you. Have fun!

May 12 - 10:00 am to noon - General Orchid Culture (A general introduction to orchids and how to grow them)
June 2 - 10:00 am to noon - Repotting (We show you how to pot or mount that favorite plant)
July 21 - 10:00 am to noon - Cattleyas (We teach you all we know about our favorite genus)

[Aniko]

Boxerfan - Your concern might have a foundation, because plants are photo sensitive, their life cycle is correlated with day length and day/night alternation.Many plants, Poinsettia for ex., needs complete darkness and long nights to bloom.
I read that phals need cooling and longer nights to bloom. My experience is that they just bloom and bloom...

[kmarch]

I seem to remember from my college biology class that all plants have a day/night cycle they go through, I seem to recall it was likened to inhaling and exhaling. I think photosynthesis shuts down at night (no light = no photosynthesis) and the plant "rests" a little. As I have always lived either in the city or a suburban area, there has always been some degree of "light noise" as they call it, at night: e.g. parking lot lights or streetlights. My orchids have always been exposed to some of this light, all night long, all year long. I believe this kind of light is far to low in intensity to matter.

Any professional biologists as members who can fill us in on this?

[janet_a]

i don't think they're as sensitive as, say, pointsettia in needing pretty much total darkness; but they do need a definite day-night cycle.

[kmarch]

Janet,

I don't remember much form my high school biology days about this day-night cycle. Can you elaborate on this a little?

[pikevi]

I think all organisms with the exception of a few are diurnal following the light/dark rhythm( circadian rhythm), based on the sun.

And all animals will be affected in some form if this is interrupted or even reversed. ( jet-lag is an example)

Many shift workers have many effects on their physiology because of the 'shifted' pattern of living. An important master gland( pituitary gland ) at the base of the brain is what causes the negative effects, along with some degree of psychological dependance.

The whole LIFE on the planet is dependant on the SUN.

Plants, I am sure , would require light in some form to be able to synthesise chlorophyll. I am not sure if reversing the day/night cycle will have any effect on plants in the long run.

May be a botanist can tell us more about plants and light

[janet_a]

actually i just saw something about length of day and blooming... ah

http://www3.imperial.ac.uk/newsandev...2?newsid=10174

hmm, this is also interesting...

http://www.hrt.msu.edu/faculty/Runkl...d%20Runkle.pdf


photperiodism generally

http://users.rcn.com/jkimball.ma.ult...periodism.html

and there are actually several organizations out there trying to reduce light pollution. who knew?

[Sharyn]

Janet: Interesting links. Some of the info a little too technical for me, but the cooler temperatures to induce new spikes makes sense. Our spring temperatures here in Illinois have triggered many of my phals to shoot out new spikes within the past week! I was surprised and delighted. Thanks for the links.

[DDS2007]

Janet,
the second link is very informative and interesting, i have kept it in my orchid documents for future reference!
thank u

[pikevi]

Thank you janet_a.

Very informative URLs.

[PhalPal]

I think that all the books and experts are assuming the grower has their phals under artificial lighting. An old practice was to keep grow lights on 24 hours a day and it disrupted the flowering and growth of the plant. Now the rule is to turn off the artificial spectrum lighting over night to let the plant 'rest'. Considering how close an orchid has to be to benefit from 4 tubes of cool/warm artificial lighting (inches!) I doubt if a dim light at a fair distance (a few feet) would have much effect.