You write:
I've read that leaving plants/their roots in the ground during the winter allows for microbial activity to last longer and begin earlier in the spring, as well as reducing the moisture lost to wind and sun (until snow covers everything), and reduced mineral erosion from the snow.

I assume you are talking about leaving tender plants in the soil. Where did you read this? I've checked several University Extension sites and can find no such benefit from leaving tender plants in the ground. You can leave tender perennials in the ground because sometimes they will winter over, but there is no benefit to the soil from doing this. The exception, of course, is if you are using "green manure" like annual rye grass that will add nitrogen to the soil.

The mulching that you have done with compost and leaves should work very well. However, leaves are best used after having been shredded. You don't want leaves to mat down and prevent moisture from penetrating into the soil. "Chunky" types of mulch that has air spaces in it like wood chips or shredded leaves allow predatory beneficial insects to flourish and help keep slugs away.

I tend to put shredded leaves in a large pile over the winter and then apply them to beds in the Spring when they have begun to break down a bit. But putting them on in the fall will work well too.

Steve

I'm with Steve, although I suppose leaving plants in place might help keep the mulch from blowing away.

"What methods do you employ to ensure the garden bed stays as fertile and workable as possible next spring?"

At this late date there isn't much else I can do in my zone 6 location. It all depends on what your site is like I guess. I have lawn, surrounded by shrub borders and a long mixed border with perennials and grasses and that has plenty of plants in it so I'm not worried about soil erosion. I also don't have a windy site, being on level ground surrounded by trees to the North and West for the most part. So a layer of chopped leaves in addition to the bark mulch that was on there all summer, is all I think I need.

I have another bed that is frequently changing with mostly perennials and this year, I pulled out a lot of plants and so there is a large area that is empty, so I did add a thick layer of half finished compost and a layer of leaves gone through the lawn mower on top of that.

My vegetable beds are raised with a foot high wooden frame and those beds get most of my attention in the Fall. Once I pulled out spent plants, I dug in a lot of kitchen scraps, torn up cardboard, the finished pea foliage. I buried those mostly around the edges and in the corners, so I can still plant early around the scraps. I also added a thick layer of more chopped up leaves. Some years I sow a cover crop in any areas that are empty, but that would have needed to be done back in September. I did that last year, so I'm skipping it this year.

Some years if I want to expand a bed, I do it in the Fall because I can layer in a lasagna method, along the area that is being expanded and no digging out lawn in the spring. I find by doing this, the soil is in very good shape in the spring and lots of worms when I start to work it.

I was just reading a book written by an Amish gardener. She used a radish crop, that she sows in late summer/early fall, that she turns under in the spring and she found this improved her soil a lot. Again, we are talking about the vegetable garden. Another thing she did to improve her soil, was to add spent mushroom compost as a mulch and hay that was sitting for 2 years out of the way on the property would be carted to the vegetable beds and used for mulch during the growing season. Although she did say she didn't enjoy using it because of all the critters in the hay by the time she was ready to use it.

That's about all I do. Some people might add lime or wood ashes in the fall in areas where it was needed.

steve: These are a few article's and books I've been reading. I've gleaned the "facts" or myths, I guess you could say, from a few of these sources:

This extension service talks about the microbial activity which is increased in tilled vs untilled soils, but also talks about how this causes the organic content of the soil to be depleted more over a longer period. I read this as 'leave plants untilled over winter'. http://ohioline.osu.edu/sag-fact/pdf/0016.pdf

The colorado state extension recommends leaving any root vegetables in the ground after frost but also recommends cutting perennials to 1-2 inches above the soil line: http://www.colostate.edu/Depts/CoopExt/4DMG/Garden/longwint.htm

An older book titled Edible Landscaping by Rosalind Creasy (which has become some sort of Bible for me) comments on erosion, "...some general principles apply for protecting the soil. They include: 1. Maintaining high organic content of the soil, 2. Applying mulches and planting windbreaks to protect against wind erosion, 3. Planting a winter crop or leaving stubble of the summer crop to reduce exposure of open area..." (21).

I guess a combination of the literature and personal experience has led me to this belief. The area I'm living at currently in Chestnut Hill has a public garden where every last plot was left standing (dead vines & bushes or stubbles of plants, but plants are never uprooted).

What do you think about it steve? Do you typically pull up all of your summer crop and mulch over for the winter? This year I trimmed most of the unwieldy bushes and vines down to the soil line, and others I simply left as they were to die back on their own.

prairiemoon:

We tore out one of the elm trees in our back yard a month ago, and I'm employing the lasagna method where there's now a giant gap on the border. I'll be adding more compost on top of the upper layers when I get home this tomorrow seeing how there's *finally* rain today!

I used the lasagna method this year where I plan to plant pawpaws in the coming years. I figured that I might as well begin drawing worms up and adding nutrition so that when I finally get around to buying the pawpaw trees they'll take right off.

To all who mentioned winter rye: Where do you purchase the seed? Do you save your own seed from previous green manure plots?

Persimmons, that's a great idea doing the lasagna method where you are going to plant trees.

When I've done cover crops, I have stayed away from winter rye only because I read reports that it sometimes persists and doesn't break down all the way. I called Johnny's Seeds and they talked me through what I needed and I ended up using Hairy Vetch. I had raised vegetable beds that I want to turn in the cover crop by hand and that worked out great. I didn't have enough room to allow it to set seed and collect it, so it does get expensive. I bought mine at Johnny's which is expensive. I think I did look for less expensive organic seed and I found some but I don't remember where. I would think a google search might find a good source.