Thanks. I don't think I have the stamina to make 700 paper pots, so a
blocker will have to be bought.
In regards to the GH, I do have some experience about gardening under
cover. In the tunnels, soil is the only ballast and the tunnels buy
approximately 1.5 zones. I do think that a combination of a hot
composting trash can, the oil drum full of water, and a non-touching
second layer of poly will buy me 3 zones in total. Possibly not enough
for melons, but keep in mind that here second-to-last frost is often
one month before last frost. I can transfer things in and out if it is
only one or two nights in the late spring. This year, for example, the
last time it went below 25 was in march. We had one night at 32 in
april. that was that.