Yes, I run two. They run a bit hot so if I want 70 turn to 68 or so. However they both run at the same temp, so that is a problem if your growing different seeds. If you want 2 mats at different temps you have to have 2 thermostats. Most seeds give you a range for temp so I run everything a on the cooler side of the range. Mine has plugs for 4 but my greenhouse is not that big to accommodate that many mats. Also one can only manage so many seeds. One 5 place mat is more than enough to grow seeds. I usually use the other mat for cuttings like coleus and Pels. They seem to root faster with some heat and I can keep the air temp cooler. I start my begonia seed on New Years Day, then petunia and other faster growing annuals end of Feb. or first part of March so that takes care of the different temp requirements.
