Do most orchids have bloom triggers like temp or light?
 

I think we mostly all know that a Phal usually wants some cool weather before it'll bloom. What about the other (more common) orchids. Yeah, I know there are something like 25,000 species and another 65,000 hybrids or something crazy like that, but it seems like most of the common orchids fit within a few (relatively) common groups. Do those common groups share the same or similar triggers. IE, Catts, Cymbidiums, Dendrobiums, Oncidiums, etc....

Is there a general guideline that you can use for the groups and then assume there will be a ton of exceptions. I would assume they should almost all have some sort of trigger since in nature, the same kinds of plants would all want to bloom at about the same time to increase their chances of reproduction.

It seems like the most likely candidates are temperature (cooling down in the fall or winter or just after cool weather in the early spring) or it seems like I've also heard about hours of daylight (presumably the plant then knows what time of year it is and is ready to go).

What about the really tropical varieties? I visited the Amazon in Brazil. All year long, the amount of daylight varies by about 10-15 mins, and the temp probably doesn't vary by much more that 5-10°. They do have quite variable rain patterns though. Dec/Jan-May/Jun it rains, and the rest of the year it rains less.

Some of the Pleurothallidinae and Bulbophyllum that I grow do not seem to care about temperature, light or a rainy/dry season (another trigger for some orchids). They bloom all year, seemingly without a trigger. This does not apply to all of them, though. Some are seasonal.

Interesting, thanks for the data point.

My guess is that they all have bloom-triggers. But that you'd have to be an orchid of that kind to be tuned in to them. And that even some of the more obvious ones which we (strangest orchids of all?) might notice are combined with other more subtle ones.

That would explain why some people swear you must give your phal a bit of cold, and others are like "Meh."

True. I've seen that there doesn't seem to be 100% agreement on the Phal trigger, although I have to say I do buy into the whole temp thing (not through any specific experience of my own).

and here it is, over 100 degrees almost daily, and those stupid phals are putting stalks up.......that's what I get for buying $2 plants at the grocery store....coming out of the a/c of the grocery store into my 90 degree gh....they are just plain confused!

While it doesn't hold 100% true (nothing in the orchid world does...), generally speaking, orchid species that have blooms in the white/pink/purple range tend to require the cool period treatment to bloom, while those with yellow/orange/red do not.

Hybridized them and it's anyone's guess.

From this paper

Research on Orchid Biology and Biotechnology | Plant and Cell Physiology | Oxford Academic

"Temperature has been reported to control flowering in several orchid genera such as Dendrobium (Rotor 1952), Miltoniopsis (Lopez and Runkle 2006), Phalaenopsis (Sakanishi et al. 1980, Blanchard and Runkle 2006) and Zygopetalum (Lopez et al. 2003). The promotion of flowering in these orchid genera by exposure to low temperature suggests that flowering in other orchid species could also be regulated by temperature."


In addition, photoperiod is another factor that controls the expression of genes involved in flowering initiation. (no time to read the original papers though).

Well I guess the orchids have evolved to know the best time to bloom, or basically when the pollinators are up and runnin around and about. I guess. That is the key word. I do not know for sure if the blooming time is fine tuned to times when pollinators are active, but that is my best guess since all plants want to do is propagate. Aditional stuff like eating bugs, making delicious fruit and growing really tall just aids in propagation.

Enough about plant's life goals. While I think that 95% of orchids have a certain trigger, I think some really just don't care about weather and flower whenever they want. An example is some paphs and bulbophyllums. Some orchids may have blooming triggers that happen very commonly or are very subtle, making them seem to have no blooming trigger. Some plants, although I am not certain for orchids, bloom when they have run out of space to propagate vegetatively.

Ray, thank you. That's interesting. The orchid world seems to be as much about exceptions as the English language, but at least there are some patterns here and there.