Diurnal temperature for phalaenopsis

[Rwhb12]

An interesting read Temperature during the day, but not during the night, controls flowering of Phalaenopsis orchids | Journal of Experimental Botany | Oxford Academic

Russ

[Gardening in WM]

It has been known for a while now that temperatures above 28 degrees C stops the flowering but it's interesting to see one of the hybrids they used didn't even like 26 degrees either and only flowered best between 14 and 24 degrees C.

One thing all of these studies do not take into effect is light hours. I have read of a further study that showed a reduction in light hours as experienced in fall into winter will promote spike initiation.

Having grown phals for a few years and tried to experiment a little myself I have found that they are light sensitive more than temperature sensitive. This study shows they need a range of temperature to flower but if the study were to be performed for more than a year at constant temperatures instead of just 20 weeks at a constant 12/12 photoperiod and the yearly light changes are taken into account they would find that phals like to flower the most during spring, summer and autumn (as long as temperatures do not exceed 28 degrees during the day).

In other climates where in summer it is hotter than this they will adapt and might prefer to flower in winter time when the temperatures are in a better range for them as they do like to flower a lot if the conditions are just right for them.

But in my climate they like to start spiking as light hours reduce, they grow the spikes over winter to then flower in spring through summer. Then the cycle repeats again in autumn.

This article shows the temperature has very little to do with it, only needing to be in the right range of 14-24 degrees ideally.

They can be manipulated a lot though, warmer temperatures makes them grow faster, lower temperatures slows them down so everyone has different seasons for their phals depending how they are grown

[dbarron]

I know phals prefer warmth, but sometimes they're not important enough to us to treat well (speaking for myself). And one that I bought last year on sale, lived all winter in the almost unheated laundry room. Bearing in mind we got terribly cold and pipes were busting all over town, including in my laundry room. The air in the laundry room remained above freezing, but definitely not warm most of the winter.
The phal didn't grow fast, but did keep growing leaves and spike through the winter, with no ill effects. Oh, should mention this was a hybrid, not a finicky species like bellina. These things are tough....no doubt.