Oncidiums & bottom heat?

[greenpassion]

I have all my orchids in S/H, and up until recently, they were all under LED lights, not window sill culture. Given that I recently have aquired the room (and a new large east facing window) I have moved my oncs as well as several mini phals to the window, and they are on a heat mat. It occurred to me that maybe oncidiums don't like bottom heat as well as phals do. I have an ondontoglossum there as well, which has bloomed numerous times for me under the lights, but now looks to be in ill health. It's bloom period is over, and I have noticed 2 new puedo bulbs coming up on the sides, but the plant as a whole looks like it may have something. The other oncs and a mini twinkle also look spotted. I can't send pics, but will have to make do with adivce unseen as it were. I have been spraying a mild solution of physan 20 every few days, and this seems to be helping. I can't help but wonder about the heat matt issue. Is it unconnected?

[cbuchman]

I was using a seedling mat too, but I noticed that the bottoms of my pots were very warm to the touch and removed them from the mat. Where I have a space between the mat and pot, this works better. In other words, the pot doesn't directly touch the mat.

The exception is for my Phasls. I use the mat since my space in on the chilly side for phals (in the 50F at night). Most of my phals are in plastic pots inside clay pots. I often put a little something in the bottom of the clay pot to provide stability. S, in essence, there is an insulating space between the mat and the roots. It's warming up now, so I'll unplug the mats shortly.

Remember too that Oncs (and their relatives) will want some chilly time to set buds.

I'd be very interested in other peoples' experiences, too!

[orchidsarefun]

I looked up a couple of onc hybrids/species in OrchidWiz. I couldn't find any common ones that like it "hot". Cultivation temps for all were mostly between 58 and 75f at night. I hope the above info helps and can be applied to your conditions.
Mine are not in s/h but I follow basically the cultivation guidelines in OrchidWiz, with a Summer vacation outdoors, and all of them flower like clockwork. And these seem to be disease and pest free.

[silken]

Some oncids hybrids have quite cool growing relatives in their heritage as in odontoglossum so I could see the roots of those possibly not liking the heat mat.

[Ray]

I think you're all missing the purpose of bottom heat. It really is not intended to affect the cultural conditions of the plant, but to stimulate root growth.

Plant metabolic rate is directly related to temperature; by applying the warmth to the root zone, a plant will preferentially direct its growth energies there.

About the only reason I am aware of that heat mats ARE used as a "culture modifier" in in plants grown in semi-hydroponics in cool, dry environments, where the heat is intended to compensate for evaporative cooling.

[greenpassion]

Thank you all for your quick response. I'm glad I posted that question, as I have had all my phals and oncs on heat mats routinely. I just went down and turned the mats off.