There are devices out there for about $20 that heats the bottom of the tray to stay above 75 I think is the temp. During the winter I am required to use one on not only the clone tray, but the seedling tray. During summer months only the clone tray.

It, in my opinion, helps much with the process.
WashougalWonder Reviewed by WashougalWonder on . bottom heat w/ clones just tried my hand at taking clones today for the first time. my reading has told me that bottom heat helps with root production and can help to increase humidity. But is there such a thing as too much bottom heat? can too much kill roots? Rating: 5