Quote:
Originally Posted by Orchidtinkerer
I am more interested in what makes phals tick at the moment. This might be coincidence but all 8 phals that are blooming here at the moment were given 8 hours light/rest over christmas. The 15 phals I decided to give 12 hours of light all through winter are all doing nothing, every single one! Which is not what I was expecting at all.
Coincidence? Not sure.
As to it being fact that some species are triggered by the cold, I would say that is based on old facts, it was once fact that the earth was flat, doesn't mean it actually is, I haven't got enough evidence yet but it surprises me as there are growers that have been growing decades longer than me and there should be more evidence!
It is fact that commercial phal growers keep temps above 28 degrees to inhibit flowering. When they want them to flower they lower temperatures - this enables flowering. There is a big difference between enabling flowering and triggering flowering though so it is complicated but the only reason this would then be interpreted as in temperatures trigger flowering is if if was observed in nature, as temperatures drop, the ones that flower do so. But why does the temperature drop? Because daylight hours reduce. So if both happen at the same time you could decide it is the temps but it could just as well be the light hours reducing which in turn reduces temps and there would be no way of proving it one way or the other without trying different conditions one year after the next. ie cold rest + supplemental light, no cold + light, cold with no light and warm with no lights. And with several different orchids.
A cold drop at night improves flowering for every orchid so I can completely understand why it is thought to be so but I don't just want to have an asnwer for the sake of it, I want the right answer so that I get better results.
Could I have gotten the 15 phals I gave 12 hours of light over winter (using electricity I might add) to flower? Most likely yes but I will have to wait till next year to try something different again.
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Sounds like a nice experiment you have going. Do you mean that the plants that recieved short days over christmas are now showing spikes? I wonder if it is due to your light treatment though, since spike induction usually takes 4-6 weeks. Another thing is that it has been pretty well researched that when it comes to bloom induction, the majority of Phals are temperature sensitive, and that photoperiod plays no role. This topic has been of interest for commercial growers because maintaining greenhouse temps over 28°C is really expensive, and if playing with short and long daylength (far cheaper) were the solution, it would be used.
Why is there no photoperiod sensitivitiy? Because most Phal species originate from areas close to the equator, and daylength doesn't vary much. There are exceptions to this of course, and one example is Doritis (now Phal) pulcherrima (a spring/summer bloomer) which has been found to be photoperiod sensitive. However research showed that spiking in this species is triggered by lengthening daylength and not by shortening it.
As to your results with short versus normal daylength, it may very well be that by turning off the lights earlier, the plants experienced a slightly lower average temperature than the other set of plants. Iradiance from light fixtures will raise the temperature at leaf level somewhat, and it can sometimes have stronger effects than anticipated! (As I discovered last year in one of my experiments at work...)
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