Uninterrupted darkness?

[plantaholic]

Okay, I'm now thoroughly confused. Some books/people say that some orchids (which ones?) have to have X amount of uninterrupted darkness at night in order to flower. Some books say nothing about this. Some people have said its not true. Now, I know that this is the case with poinsettias - granted, that's not an orchid but it IS a plant! So, please some help - what is the truth? Are there orchids that need totally dark nights? And, if so, how does one accomplish this when growing on windowsills in town? I need answers soon. Otherwise, I do believe I shall go mad....or am I already? Otherwise, why on earth would I continue to add orchids to my already limited living space?? Especially if I can't get some of them to bloom because of streetlights, nightlights, and other lights that come on in the night.....

[isurus79]

That uninterrupted darkness stuff is garbage. Your plants will flower just fine in the city! Mine do!!

Now, as for the madness, you're already a member of the OB, so I'd say you've already lost it!! lol

[BikerDoc5968]

I don't know about "uninterrupted darkness", but asyou are well aware many plants flower in response to their specific photo precocity...that is related not so much to darkness but lenght of daylight. This is why you find Christmas cactus, some call them Thanksgiving cactus, selling in stores in early November because they are forced to flower by changing their day length. Some orchid growers, I believe, force cymbidiums by changing the day length, watering habits and temperature. In my GH I just let Mother Nature dictate the rules. I don't use any artifical light source and my phals do just fine.

[ckollmer]

I too have read this in older references. However, in my 7 years experience, I have not found "total darkness" to be an absolute prerequisite for flowering. Keep in mind that plants use many cues, such as duration of daylength/change of seasons, diurnal temperature variations (day/night), genetics, etc.. Most hybrids - cattleyas, dens, oncidiums, etc. will bloom when their new growth matures, assuming that the plant is mature and capable of flowering. For Phals, cool night temps seem to be more impt wrt flower initiation than photoperiod. I don't have experience with species, and it is possible that they are more sensitive to uninterupted photoperiod.

[magicatt]

When I was growing african violets for show, I was told they needed eight hours of darkness to produce florigen. The hormone that makes them flower. If african violets do it, why not orchids? I would'nt worry about total blackness, after all there is a moon in nature.

[RosieC]

I've never heard this, my Phals and Dend grow in a window with a streat light just outside and I've never had a problem. The Dend has not lost it's first flowers yet so I can't judge it it will re-flower in that location, but the Phals have all re-flowered several times and they grow really well.

[Ross]

There are several plants needing total darkness for a certain period such as Poinsettia or "Christmas/Easter" cactus. But I am not aware of an orchid that requires same regimen.