VIVOSUN Durable Waterproof Seedling Heat Mat Warm Hydroponic Heating Pad 3'' x 20" for Kombucha Tea & Beer Brewing, Fermentation, Seedlings & Plant Germination

They work great get the seeds grown keep the soils in the pots warm good way to get on with gardening

Perfect size 3.5" for window sills to get a jump on spring.

I use this to keep kombucha at a good temp while fermenting. It works perfectly for this application on a one gallon jar. I was a little worried about temperature control but it keeps the liquid at the perfect temp. I can't speak to it regarding plants, but if you're trying to keep a gallon of liquid warm, this will do it.

Works well, thanks

I have 3 of these types of strip heating mats. I use them to go around my gallon sized kombucha jars during the winter and they work fine. They keep my fermenting kombucha at just the right temperature. Two of these mats I've had for years and only purchased another one fairly recently. I find them to be very useful and am very pleased with them.