A few years back, we put energy efficient windows in our basement. I could not part with the old windows; I knew they would make a great cold frame for extending our Minnesota summers.  After looking at plans online, my husband built me this great little device.  It is insulated and everything! 

My problem is, what am I doing wrong?  

I put in my raised bed about 8 weeks ago, then planted spinach inside.  Two weeks after that (when I thought the ground was warm enough), I sprinkled some tomato seeds on the other side of the cold frame. 

Results:  weak.  I have ONE spinach plant growing and some of the

plants look like they might be tomatoes.  Note: the violets and clover sure are growing nicely!

I was hoping to have an overabundance of sturdy Roma tomatoes for the Greengirls Plant Swap on May 31, but they might be little weaklings that no one wants to trade.  I’m pretty sure this season is shot for using this contraption.  Any recommendations?