Heat pads, terrariums and Semi-hydro

[TylerK]

I have about 40 orchids in s/h right now...started trying it with three plants about three years ago. After some success, the next year I transferred another 15. All my orchids, with the exception of three seedling paphs are now in s/h.

The biggest barrier to acclimation (with every single one of my plants) has been getting the first few new roots down through the dry top layer of the medium, down into the moisture. Once a few new roots have grown into the meidum, other new roots no longer seem to have this problem - they find their own way past the dry zone without stalling or developing brown tips.

Last year, to try to circumvent the problem, I bought a fogger and a large glass terrarium. Through the summer, it worked great. The medium was always damp, from top to bottom, humidity was always up around 100%, and temperatures were fairly consistent around 22C at night and around 35C during the day. The winter however was not so ideal. The night time temperature of the summer became the daytime max during the winter, and it was usually around 17C at night. I'm assuming that the temperatures within the pots themselves would be somewhat lower. New roots just tended to skate along the top of the hydroton.

The established plants I've decided to keep outside the terrarium, even if that means having to water more often. For those I'm going to buy a heating pad for the winter. Do you think I can buy a heating pad for the terrarium as well though? The plants I just transplanted into s/h will probably benefit from the added wetness over the winter, but I don't want to expose them to the colder temperatures. I'm not talking about putting the heating pad right inside the terrarium, but rather sitting the terrarium on top of the pad. Do you think this would work, or are there other better ways for heating the terrarium?

Thanks,

Tyler