i might be more worried about proper light first ... all cold does is slow things down.. but light is imperative ...

might we have a pic of what you call a bin ??? .. it will help us hone in on whats needed ...

where is the bin kept .... on a cold floor??? .. near a furnace duct??? .. in the colder basement???

more facts.. better answers ...

and i presume the coldest temp is at night when the furnace kicks down??? .. in other words.. if you decide to use one.. it might only need be on at night ... on a timer ....

i never used a heat mat on houseplants .. not sure its needed.. as most common houseplants multiply so easily.. [thats why they are common] ... i did use one on conifer and shrub cuttings because its more requisite .. especially since i was doing it in the basement ...

ken

I love using heat mats for my cuttings. i have never had mold issues. heating up the growing media will make for faster growing roots! I recommend giving it a try!