Viewing post #1912766 by RpR

thommesM said:Last fall I was ahead of schedule and was able to do spring cleaning in the fall. Cleaned up the beds and then topped off with 3-4" of shredded leaves. Basically, as the leaves fell, I shred them and filled the raised beds with the leaves. Rain would wet and compact the layer and I'd repeat throughout the season. I didn't really know what to expect. I hoped the shredded leaves would insulated the soil underneath so organisms could continue to thrive. I even put very hastily built, not expected to survive long cold frames with simple clear plastic over a couple of the beds. Those cold frames have since crashed and burned with the snow.

I've found that shredded leaves are a great insulator. The top 1" or so is loose and thawed but below that level is frozen. Not sure how far below that is frozen as I didn't dig down below. Still want to compare the bed to one that I left alone as a control, but as of right now, the shredded leaves did not appear to keep the raised bed from freezing. Maybe next year I'll fill in between the beds with leaves as well though two of them have straw bales between them and didn't appear to be in any better condition. I'm going to build better cold frames or low hoop frames and get 6mil plastic next year which should work much better.

How cold does/did it get there?
If you get below zero your ground is going to freeze unless you have leaves , not shredded at least two feet deep and for all practical purposes a lot more.

As Stone said the leaves are supposed to stop the frost from going deep.
Expert rose gardeners up here say you are not supposed to cover your roses UNTIL the ground has frozen, not before.
Now this is partly for disease control but that frost layer also acts as a barrier..
For roses and it works the same for anything , Oak leaves are those that will compact the least and remain dry offering the insulation similar to a down coat.