Bottom Heat-- how important?

[Pilot]

Hello--

I recently transferred my phals to hydroton medium as I've used this stuff before with other plants and it has worked well for me. I do have a semi-hydroponic set up for these phals as some suffered from rot in their NEW bark medium. I'm still willing to try bark but that is for another time.

Anyway, I know that in cases of cuttings of other plants-- such as hardwood trees (IE crabapples)-- the use of bottom heat spurs root growth and you get healthier rooted cuttings faster and in the end healthier. So...

I got a hydrofarm heat mat and placed it under my phals that are in their water reservoir in an effort to help stimulate new growth. My question is how important is bottom heat really to phals? Is my attempt at applying heat to the roots even fruitful considering the cooling nature of evaporation?

Thanks