There's never enough room on the seed mats in January! Our new boxes (on right in pic) have helped. We've captured another several square feet of climate controlled space near, if not on, the heat mats. The mats sit inside the styrofoam boxes, holding eight flats of seeds, and letting us add additional six packs to edge where they harden off a bit before moving into the open air. This especially helps hold heat at night when we have to turn the mats down (or off) to save power (being offgrid requires making hard choices--no nighttime tv for us!).
What are we starting? Penstemons, agastache, salvia, daisies, bundleflower, campanula, hollyhock, canterbury bells, scholar tree, privet, dutchman's pipe, geranium, pansies, petunias, passionflower, grasses ,iberis, sundrops, buckwheat, evening primrose, coneflower...and much more. Lots of new annuals, some new perennials too, mostly natives.
So as one batch comes off the mats, another immediately goes on, and the oldest shuttles into stronger light, and cooler parts of greenhouse one, from seedling trays to six packes to 4 inch pots, and eventually into greenhouse two, and come April, we'll be trying to squeeze maturing plants into greenhouses three thru seven.