I want to harden off all my vegetable seedlings a week or two before
planting in the garden. My problem is that I don't care for the fact
that I have to carry all of them in and out of the house each day. I
have several styro coolers with lids that are just sitting in my
basement. Would it be possible to bury these coolers in the ground and
use them as cold frames to harden off my seedlings? I could remove the
lids during nice days and then place the lids back on at night to
protect them from any frost we might still get in my area of PA. Or
perhaps instead of burying the coolers in the ground, I could just pack
soil and sod around them. I dug a new garden this year had have a huge
pile of sod in back of my shed that I would like to find some sort of
use for. Does this sound like a reasonable idea to harden off my plants
or would it not work at all? Thanks in advance for your advice

Rich