The difference between February seedlings that survive and ones that don't is 20 by 8 feet of controlled light.

This greenhouse frame is aluminum—rigid but light, holding straight through wind and snow load without needing internal bracing that cuts up your walkway. The polycarbonate cover diffuses UV and holds heat, so the interior runs 10-15 degrees warmer even when the frost hits hard outside. The layout is completely yours: no shelves bolted down, no layout dictated by someone who's never actually grown anything. Hang shelves where sunlight pools, stack trays where you need them, leave floor space for repotting and starting runs of seedlings.