Last fall I read an article in Mother Earth News about a mini homemade root cellar made out of a 5- gallon bucket. Here's the link to the article: Mini Root Cellar. It looked feasible.
I didn't have a spare 5-gallon bucket floating around so I found a deep, plastic, Rubbermaid-style, container. I drilled holes in the bottom and prepared to bury it out in my garden. Fitz pointed out that it would stink to have to dig snow to pull out my carrots, so I decided to bury it at one end of the high tunnel. I didn't have a spare straw bale lying around either, but I had plenty of leaves, so, after filling the container with unwashed carrots from my garden, I piled a mountain of leaves on top of it.
This is what I brought up from the garden and chicken coop the other day - in mid-February!
Aren't they gorgeous? They smell wonderful! I don't think I've ever noticed in all the years I've been buying them from the store, that carrots have a wonderful "carroty" scent. I've rinsed these off and they're still a bit dirty. I found that the leaves that I had piled on top of the bin are a bit of a pain to pull off and then they fall down into the plastic container so you end up with leaf bits all over the carrots. Next year I will definitely put a straw bale over them.
If you are growing carrots (and I imagine this would work well with other root vegetables). Follow the link above and give this a try. I think you'll be pleased with the results.