I grew my orchids in the room next to an unvented gas fireplace for several years and never had any problems. I'd often put blooming ones on the mantle.

If your fireplace is functioning properly and burning completely, you shouldn't have a problem -- at least, that's my understanding. If it's putting off enough fumes to drastically affect your flowers, I would think that it could be causing problems for you, too.

You can always try it and see, call the manufacturer of your fireplace, or call a local store and see what they have to say about it. I'm definitely not an authority, but I never had any problems. :)

Stacy

Stacy, thanks. I just had the fireplace setup cleaned, and I have a carbon monoxide detector in the room showing zero all the time, so hopefully it's OK.

I agree with turkey. A big drawback to a fireplace is the huge amount of heated air that is vented, modern FPs have heat exchangers to capture that vent heat. If yours is newly cleaned and "draws" well as a good design would, I think you will have no problem with your orchids.

As long as there is complete combustion of the gases, there should be no problem. However, the air around the plant maybe rather dry. Might desiccate flowers prematurely.

My understanding is that one of the by-products of natural gas combustion is water, so a ventless gas fireplace actually makes the interior air *more* humid. If the fireplace is working properly there should not be any "fumes"--just H20 and CO2. I hope I'm right, as we're also considering one of these fireplaces.

Have a look at the following link.
http://www.geocities.com/rainforest/6847/gaschem.html

It explains natural gas chemestry pretty well. To sum it up though, you won't just be getting CO2 and H2O. You'll also be getting small amounts of carbon soot, carbon monoxide and nitrogen compounds. The more efficient your fireplace the less soot and carbon monoxide you'll get, but you won't escape the nitrogen compounds. They might not harm the orchids, but in high enough levels they aren't that good for you.

Tyler

This is similar to one of the problems I deal with, growing indoors, as I do... our winter heating source is a wall-mounted propane unit. It dries the air terribly, but other than that, it doesn't seem to have an adverse affect on any plants. Two ceiling fans at either end of the one large room circulate the air very well. Compensating for the dry air, and the lower winter light, seem to be about the only things I can do to help.

I will be very glad to move into a home with normal heating and cooling systems, which should happen in about a year!

For 8 years I have had a small ventless gas heater in my orchid room...never lost a bloom or got a headache from any fumes.

Danny

I have a natural gas unvented heater in my growing room & have no problems with my orchids.

Thanks everyone! Fireplace season is almost upon us again. However, I've decided to display the blooming orchids in the dining room instead, mainly because there is really good indirect light there. I experimented with putting some blooming phals in dark rooms last winter. I left them there too long even though I didn't overwater, and it's been a long process getting them healthy again.

I'm pretty sure that ventless fireplaces have hazards especially in producing harmful gas by-products like carbon monoxide. If this kind of gas does harm to humans, it should affect blooms as well.

Here is a link that might be useful: Ventless Fireplace Hazards