Yeah, I always thought placing them on the side would be wasteful, energy wise, but that's probably why some consider it safer. I.e. if it can't heat much of your terrarium to start with, it shouldn't be much of a problem if it overheats. Do you think a heat mat would work through an inch / an inch and a half or so of soil?

Qwerty 3159, I'd like to avoid heat mats, but heat lamps don't seem to be quite cutting it in my case. I have a 100W bulb in there right now and the air temps on the warm side are around 25C (77F) during the day and the basking spot surface is around 26C (78.8F), and we're not in winter yet. It was fine like that for the first winter, but after that, things got out of whack (eating-wise). Although, to be fair to winter, it started during the really warm summer we got last year. I can't be completely certain it's temperature related, but it could be a factor.

Maybe a 200W ceramic "bulb" would cut it, but that seems like a lot of wasted energy.

Do you think the rock thing is a decent idea, or is air temp more important than surface temp / temp directly received from the light.

Also are there any rocks that are unsafe for garters and how can you tell a safe one from one that isn't?

That thermostat is a bit expensive for me, but if I use the heat mat that's already on there instead of buying a new one, that could be alright.

Finally, are seedling heat mats alright for this job or is the strength likely to be wrong?