Spring arrives at a Mini Cone Greenhouse

I planted the first of my 2011 potato crop the day before the first day of spring this year. I covered it with a mini green house that was made of damaged green cone components.
I just created this blog post to get you thinking about this and get some comments from you. My objective is to get two crops this year by starting early.
What crops do you think might be suitable for this set up? This one is a sprouted red potato. This is an early short growing season variety of potato. My plan is to later, after risk of frost is over, to remove the mini green house and replace it with a raised bed made from the tire, presently holding the mini green house in place.
With this concept, we could plant a 1000 plants this way. Just need a place to grow them and a rototiller.

I covered the potato seed with soil before placing the cone over it and then I put a mini-max thermometer inside so by the next day would know the current range of temperatures compared to outside. The area is very wet so I do not expect the ground to freeze now. The first morning, for comparison, I found that there was no frost inside a cone with no lid that had been sitting near by the mini cone greenhouse although there was frost on the ground around it outside the cone.