I remember your window covers alright because I covet them! The problem is that in my ecosystem, mold is a major problem and the house is second hand. Our
land is lovely, but the people who thought that a double patio door in the bedroom on the north side of the house needed to study the physics of heat movement! I would love to cover the window with more than just drapes, but it is too large, so would need at least two panels, but even then the panels would be awkwardly big.
I do have a south window for starting a limited number of seedlings. However, our winters are very cloudy, and we don't have snow to reflect what light there is. It's on my list for the next few days to get some seeds germinating and I have already moved a few plants out on the porch to start hardening off.
Hopefully all your seedlings will do well!