Having trouble blooming cattleyas and brasavolas

[Grim Tuesday]

I have several cattleya hybrids, laelias, and brasavolas that are large enough to be blooming size, I grow under quite high light conditions, and have now have failed to bloom for me for at least two years. The orchids live in my bathroom on top of the medicine cabinet; I have my lights mounted on the ceiling approximately 18 inches above the plants and are timed to a constantly changing sunrise/sunset schedule. The plants are in mostly medium size orchiata bark, I water weekly with a drench in the shower, fertilize with slow release pellets and they consistently grow a nice new growth for me every year, but have skipped flowering several times. I've gotten good blooms out of vandas and catasetum in these same conditions. What am I doing wrong for the cattleyas?

[Ray]

My first thought was light levels, but if you're able to get vandas to bloom, that seems unlikely.

Can you better describe your feeding regimen?

And how in the world do you grow all that "on top of a medicine cabinet"?

[Roberta]

One thing comes to mind... depending on the ancestry of the Catts, lack of temperature variation could possibly lead to lack of blooming. Vandas may be perfectly happy - they are tropical creatures that don't get a lot of variation in nature. Many Catts, however, come from mountainous environments where there there are both diurnal and seasonal variations in temperature, that might be a trigger.

[rbarata]

Originally Posted by Roberta

Many Catts, however, come from mountainous environments where there there are both diurnal and seasonal variations in temperature, that might be a trigger.

This is particularly true in Laelias, especially the miniatures.

[isurus79]

Photos of the plants would help too

[rbarata]

Originally Posted by isurus79

Photos of the plants would help too

As well as names.

[estación seca]

How long are your Winter days? If they're too short that also inhibits flowering.

[Grim Tuesday]

Thanks all! Feeding wise, I use nutricote (Orchid Nerd ™ Nutricote Orchid Food 15-Ounce (Orchid Ferlizer) 13-11-11 All). Perhaps this is the issue? I have not used it on dens that would want a winter rest, but I hadn't thought that cattleyas would need the same treatment. Do they?

A few example plants that have not bloomed that I thought would have otherwise:

Lc. Park Ridge 'Thornridge'
Laelia purpurata hybrid
Bc. Little Stars
Bc. Yellow Bird
Den. Unawi Mist

A few plants that have bloomed under these conditions (some get slightly less light):

Den. Secundum (you can see a spike in the attached picture!)
Onc. Twinkle type hybrid
Rc. Bankok Sunset
Zygo Maxilara
Cyc. Pentadactylon (in bloom here)

Attached picture of how this all fits on medicine cabinet and some shelves I installed nearby, they stretch around to the left as well

[Roberta]

Lc Park Ridge is majority C. mossiae with significant C. trianiae and C. purpurata. Those species (and C. purpurata) are definitely cold-tolerant, so very possible that they aren't getting enough temperature variation. The Brassavola hybrids? No idea, would expect them to be happy. The Dendrobium is unregistered, so no idea what is in its background.

[Grim Tuesday]

Originally Posted by Roberta

Lc Park Ridge is majority C. mossiae with significant C. trianiae and C. purpurata. Those species (and C. purpurata) are definitely cold-tolerant, so very possible that they aren't getting enough temperature variation. The Brassavola hybrids? No idea, would expect them to be happy. The Dendrobium is unregistered, so no idea what is in its background.

oops, the den is actually Den. Jaquelyn Thomas 'Uniwai Mist'