heat pads for phals
 

I live in a very coastal neighborhood of San Francisco (cool, fog, wind, salt) and I have 5 phals in my home. I want to use a heat pad for them because the cool temperatures (in my home as well) seem to be slowing their growth down. They are all in clay pots with lots of holes.
I do not want to use plastic pots, although that has been strongly recommended by the SFOS.
On the heat pad, do I put the pot directly on it or do I use feet or a saucer for the pot? What temperature is optimal for the setting on the thermostat? Do I keep it on all day and night?
Thanks. for any help.

I question the need for it. If you are at all comfortable in your home the temps are probably just fine for Phals, but there's no harm in trying.

Make sure you get a good quality waterproof heat mat intended for keeping flats of seedlings warm for germination. They often fit perfectly under a standard 10" x 20" nursery tray and are intended to be used that way. Put the pots in the tray not directly on the mat. There isn't usually a thermostat. They are pre-set to constantly keep the pots about 10° - 20° F warmer than the room, and provide some heat to the plants above.

Don't try to improvise with a heat mat or pad designed for another purpose. This is the safe simple way to do what you want. You could get a separate timer or thermostat to turn it off and on, but if you just unplug it when you know the temps will be warm without it that shouldn't be necessary.

I have one for ours because those are in s/h and they get a bit colder. but our house is 56 at night in winter and they all bloomed then even the ones ounted on bark.