what's a good way to winterize the square foot boxes in Minnesota?
I'm not sure what you mean? Like cover them for snow? Or what?
If you're not going to grow in them this winter, you could cover them with plastic to avoid leaching. Or you could use a natural mulch or other covering that would slowly break down. Or if your soil is potentially deficient in nutrients, you could plant a green maure cover crop to mix under in late winter to let it decompose by spring.
Those are my thoughts.
Here is a link that might be useful: Sinfonian's garden adventure
I like to put a 2-3" layer of chopped up leaves over mine, sprinkle them with a bit of high nitrogen fertilizer, then add an inch or so of composted manure over that to hold everything down. It all breaks down over winter, and in the spring I just take a hoe to it to give it a bit of mixing and then rake level. If I didn't have so many beds to do, I might also cover them with black plastic, then they would heat up earlier in the spring.
Here is a link that might be useful: Annie's Kitchen Garden
You know granny, I think I'm going to use your method. Probably minus the fertilizer (cause I'm cheap, lol). As soon as the tomatoes stop cranking them out I'll probably get started.
Well - I haven't put any thought into winterizing my garden. Best I can tell, it will only be vacant from about December 1st til the middle of Feb. That's when the taters are going in!
Carolyn, I buy the cheapest lawn fertilizer you can buy to use for my winter program. It's high nitrogen and quick release, and that's all I'm looking for to aid in breaking down the leaves. Lowe's sells a bag that covers 5000 sf of lawn for under $7. I'd say that would probably be enough to feed my winter garden for about 10 years!
Here is a link that might be useful: Granny's 9/26 Blog