Question about light at night

[gngrhill]

I read somewhere and I don't remember what species it mentioned, but that turning on a light at night will upset the blooming cycle. Is anyone familiar with this ?

[weederwoman]

Someone in my orchid society mentioned that a local grower told him that too much artificial light after dark can affect the blooming of paphs. I'm assuming this is personal experience, but there could be a controlled study involved too. I hope to be at the nursery on Saturday and I'll ask for more particulars. I grow my slippers at home under lights, and I try to keep the room dark in the evening. But, you know, husbands sometimes accidentally turn on the light, thinking they need to see when they are in the laundry room, for some strange reason.

[Subrosa]

Many plants use the length of daylight to regulate their life cycle. Light at the wrong time can definitely confuse such plants. I can't speak directly to orchids on this.

[Fairorchids]

Even faint artificial light, such as a street light, can ruin the blooming cycle in Poitsettias.

In Cattleyas there are two distinct groups, with short & long nights respectively initiating the blooming cycle. I do not remember which species fall into which group.

[Paul Mc]

I have a friend who leaves his kitchen lights on at night and never gets his orchids to re bloom. I told him he needs to be turning the lights off at night. His set up is perfect, it's just the artificial light doesn't help his plants recognize the shortening day cycles.

[Ray]

To my knowledge, it is primarily some cattleya species that respond to shortening daylength to initiate blooms.

I have to question the "streetlights or kitchen lights stopping blooming" as possibly being a myth (or excuse for some other cultural shortcoming). It, of course, depends upon the intensity of the light and distance from the plants, as the inverse-square law cuts the intensity drastically.

Plants don't need total darkness...

[tucker85]

Bill Peters, who owns Whimsy Orchids, in Homestead, Florida, told me that he can delay the blooming of cattleyas for several months by leaving a few lights on in his greenhouse. Since I spoke with him I try not to let lights shine on my orchids at night. Of course it's sometimes difficult.

[Subrosa]

Originally Posted by Ray

To my knowledge, it is primarily some cattleya species that respond to shortening daylength to initiate blooms.

I have to question the "streetlights or kitchen lights stopping blooming" as possibly being a myth (or excuse for some other cultural shortcoming). It, of course, depends upon the intensity of the light and distance from the plants, as the inverse-square law cuts the intensity drastically.

Plants don't need total darkness...

Obviously the level of light provided by a full moon on a clear night is something plants would have evolved to deal with.

[isurus79]

I know that Harry Akagi of H&R Orchids (catwalker808 here on OB) has mentioned at least once on OB that C. walkeriana is easily thrown off its blooming schedule by nightlights. I'd say its probably safe to assume that C. nobilior is also as finicky.

[MamaLiberty]

Originally Posted by isurus79

I know that Harry Akagi of H&R Orchids (catwalker808 here on OB) has mentioned at least once on OB that C. walkeriana is easily thrown off its blooming schedule by nightlights. I'd say its probably safe to assume that C. nobilior is also as finicky.

My orchids are in the upstairs bathroom. I don't use it a lot at night, but once in a while the overhead light will be used for brief periods, especially if I have company. I can't imagine that would upset the blooming of most of mine, and I don't know what in the world I'd do about it except issue flashlights to my guests.