Growing Orchids in a New York City Apartment in Winter

[alanbar]

It is now winter in New York City. I have mostly Dendrobiums and Phaelanopsis orchids. The Dendrobiums are mostly under a grow light table that also gets natural light from the south. One is blooming while the others are not. The Phaelanopsis orchids are on a window sill that gets mostly filtered light. None of the Phaels are blooming, but the plants seem quite healthy.
Any suggestions for how I can be encouraging them to begin the blooming phase especially in terms of watering and fertilizing? All thoughts will be appreciated!

[Mike H]

They need a night time temp. drop of at least 10 degrees. Not sure how long perhaps someone will comment with more expertise than I.
Go easy on both water and fertilizer until Spring.

[raybark]

Actually, that's close, but not quite it.

Phalaenopsis grow best if very warm-to-hot and shady, but to reliably initiate flower spikes, they need about 10 days to two weeks of an average temperature drop of 10-15F. That can be achieved with a 20-30F nighttime reduction, or by a reduction in the general growing temperature.

It's all a matter of degree, of course, and Dr. Yin-Tung Wang, then of Texas A&M, showed that with the "10 degree nighttime drop", you might get spike initiation in some plants, but it takes that average reduction to make sure.

[Mike H]

Thanks Ray, my greenhouse has been going down to 50F for about two months now and most of my Phals are spiking.
I don't expect to see flowers for a couple more months though.

[raybark]

This experiment might be of interest.

[Mike H]

Good information Ray, I looked back at my data and see that it was early September that my "average" temperature dropped and I did note that spikes started to show on several Phals early in October.
The average drop was close to 20F and I was quite busy at the time so the plants were a bit neglected so stress might have come into play.

[livtodance]

this, and the other responses too, are all very interesting as to a Phal's needs. I have most of my orchids at the office in my employer's office on his window sills. He keeps his office very cold. 68 degrees F? and they are on a southwest window sill (right in the sun (no protective screen)). They seem to just love the high light and cool environment. They will bloom at least twice a year, if not more.