Comment GROW for a link to my blog post about seed germination tips! Tomatoes are actually known for having good germination rates so other heat-loving plants like peppers, squash, watermelon etc. are probably better candidates for heat mats if you have to choose. Make sure to only use a heat mat until the seeds germinate or the seedlings will become leggy. Heat mats are definitely not necessary but can be nice to speed up the process. For the paper towel method, many people put the seeds in a z