We're a bit warmer here (Zone 8), but I leave my carrots in the ground all winter. I cover them with about 6 inches of straw. They don't usually freeze even with deep snow on them, and if the tops do freeze, the rest of the carrot remains edible. We're still eating the ones that have overwintered and will continue to until they get woody.

thanks. i will plant a extra row this year and try to eat fresh the winter of 2009 / 2010. Do you remove the straw or till in under? Would covering be easier if I plant them in a block instead of a row?

I successfully overwintered carrots this year. What I did was once the peas finshed up in June due to our summer heat, I planted that area with extra carrots. Then I covered them with ~3 inches of leaves in the fall. Have been eating fresh carrots ever since the temps have risen above freezing. It didn't go below zero degrees here this winter, but it got close. Also, it is pretty dry here (even in the winter), so maybe that helps.

I have raised beds, 20x4 feet. I remove the straw simply because what I have been able to get has a lot of seeds in it. It seems like when I remove it there aren't quite as many weeds and grass sprouting later in the spring. It goes in the compost along with the woody carrots for next year's garden.

thanks for all the valuable input people! I'm off for another go at it this year, wish me luck.