Keeping A Propagator Warm....?

I've been foliar feeding my cuttings (accidentally) so, on day 19, 2 of 24 are showing roots.
Also the sponges feel cold to the touch.

HOW CAN I WARM THE BOTTOM OF THE PROPAGATOR?
I THOUGHT ABOUT BUYING A HOT WATER BOTTLE......
Any suggestions, people?

A seedling heat mat is like 15 bucks. Or you could just get a heating pad

Heat mats are a must. The clones usually fail quickly as the temps go below 25. Try to keep the temps at 27-29.

I have a heat mat ordered from Ebay.
Should arrive Tuesday or Wednesday.

For the time being I have 2 x Alloy camping flasks (not thermos)
I fill them with boiling water
wrap a towel around them
Put them under the prop.

a heated prop is only 20pound or less in homebase? or im shore walmart is not uk, be carefull bout leaving that heatpad or heated prop on full time tho it will fry your clones, when using a heated prop i have it on a timer with the heat only coming on every fifteen minit of the hour

This requires more work, but I usually wrap my cubes in plastic wrap and tape it up to prevent evaporation. This has made a huge difference in success as evaporating water causes it to get really cold. I've never used a heat pad.

The reason I say it requires more work is because you have to water each of the plastic wrapped cubes individually.