I already answered in the other post but I only keep them on a seed mat until they have a couple sets of leaves and have been transplanted into individual pots then they go outside. If it's summer and warm I don't bother with a seed mat at all and just start them outside. In the winter I keep them on the mat for about a month and I do keep them under grow lights. The only thing I keep on seed mats for a long time are cuttings.
Karyn

Thanks Karyn, Just wondering about everyones thoughts. I think I will do a little re-arranging of my seedlings and cuttings, putting the cuttings on the seed mat, maybe get a longer grow light, so the little seedlings can be under it but not on the heat mat. Excellent excuse to take a brake from studying.

Lauri