Phal's & Outdoor Night Temperatures

[RosieC]

Mine are indoors but we don't keep the house that warm in winter. They go down arround 55 at night and a max of 66 in the day, this is low enough that they go dormant over the winter.

Last year I found all of them stopped growing and none of them spiked despite cool temps being good (or meant to be) to initiate spiking... it was just too cold for them. In the spring as it warmed up again I got a rush of spikes along with a rush of growth.

Basically they only survived over the winter, they did not thrive.

[Paul Mc]

Well, the temps dropped down to the mid-40's, and are expected to stay there throughout the week. So, I brought them all in. They had many weeks of the 15 degree difference, so I'm sure they should have gotten the signal that it's bloom time by now.

I also brought in my Dendrobium (which is in full bloom with 7 flower spikes at the moment) and two Phaius'.

The basement grow lights are back on for another winter. I'm so sad, lol...

[Claire25]

The night temps have only just dropped into the 50s where I live, and I already have spiking on a couple of my Phals. So much for needing a "cold snap" to initiate blooms...my theory is that it's more of a day length issue; many plants (poinsettias for example) bloom in accordance with shortening days, and perhaps many Phals do too.

That being said, I have no immediate plans to bring my Phals in. The 10-day forecast for my area is predicting a chilly night of 46 degrees a week from now, but the days will still be warm. Honestly, it will be the combination of cold AND wet that will make me bring my orchids in, not the temp alone.

I'll be watching the weather from now til I bring 'em in--last year they were out until Oct. 15.

Claire

[RosieC]

I think there are two ways Phals are triggered. One is daylight the other is temps.

I once heard that as a broad bush those which are pink/purple/white are tiggered by temps, those which are yellow/red are triggered by daylight.

BUT because there has been so much hybridising you can no longer tell what the trigger will be on a highly complex Phal and infact many of the complex hybrids are triggered by both.

[nutgirl]

Right now my temperatures are swinging from upper 40s/lower50s at night to mid to upper 90s daytime. The cool temps don't seem to be as big a problem if they can warm up during the day.
Rosie is right about growing warm in winter. I have also found that if the nights and days are cool, they just go into hybernation.

My hybrid supermarket type phals are spiking and very actively growing.

My species equestris are not doing as much. They seem to bloom in the summer and the temps stay much warmer then. Maybe daylight triggers them instead of temperature change.

Maureen