overwintering garden beds

Is a layer of straw over each bed good enough method to preserve the soil?  Or do I really need to throw clover seed over it?

Adding clover seed would mean you would have clover growing there in short order, do you want to have clover growing in those beds?
My understanding of setting a garden bed  up to over winter is that you want a thick layer of mulch to.mitigate damage to the soil structure and soil life from temperature and precipitation extremes. A thick layer of straw is a good way to that. I have added a healthy layer of compost underneath the straw when I have it available.
I also read a book by a Norwegian fellow who practices traditional northern European gardening and he was very adamant about putting down a thick covering of fresh cut biomass over his garden beds before winter. He claimed that fresh plant matter was better food for the soil biology. He had pictures of using heaps of tall grass and freshly cut twigs and branches.

How extreme is your winter and how long does it last?

I am thinking about using black plastic under shredded leaves this year on my raised beds. It rains all winter here, and the black plastic would help prevent the organic nutrients in the soil from leaching during the winter. I think I need to mulch over that though as I really don't want to solarize my soil either.

I use straw from my stalls in the fall. We have a pretty good amount of rain over the winter that breaks down the straw.  My raised beds get a little taller each year.  Yes, I do have to do some weeding over the summers, but I seem to have more productive gardens this way.

Jen Swanson wrote:I am thinking about using black plastic under shredded leaves this year on my raised beds. It rains all winter here, and the black plastic would help prevent the organic nutrients in the soil from leaching during the winter. I think I need to mulch over that though as I really don't want to solarize my soil either.

I'm not an expert on this but I discourage you from using the black plastic. If its under shredded leaves, what is the purpose of the shredded leaves?  Their nutrients won't get into the soil.  They won't break down as readily. The part of the soil that touch the plastic may become anaerobic. The black plastic may heat up to the point where it kills beneficial microbes.  Worms won't be able to reach the surface and deposit their castings.  Water will run off and concentrate in certain areas while the soil's moisture balance gets out of whack.

If you leave the dirt as is and mulch heavily, you won't get weeds.  Or at least, I only get a couple weeds in my 8'x4' raised bed with 4 inches of pine straw mulch.  I've had it left unattended for five months now, through the spring and summer growing seasons, and it got one weed.

Even if you do, my understanding is that weeds in raised beds get less and less as the years wear on.

I gather that some people intentionally plant nitrogen-fixing cover crops to improve soil health.

Rob Lineberger wrote:

Jen Swanson wrote:I am thinking about using black plastic under shredded leaves this year on my raised beds. It rains all winter here, and the black plastic would help prevent the organic nutrients in the soil from leaching during the winter. I think I need to mulch over that though as I really don't want to solarize my soil either.

I'm not an expert on this but I discourage you from using the black plastic. If its under shredded leaves, what is the purpose of the shredded leaves?  Their nutrients won't get into the soil.  They won't break down as readily. The part of the soil that touch the plastic may become anaerobic. The black plastic may heat up to the point where it kills beneficial microbes.  Worms won't be able to reach the surface and deposit their castings.  Water will run off and concentrate in certain areas while the soil's moisture balance gets out of whack.

If you leave the dirt as is and mulch heavily, you won't get weeds.  Or at least, I only get a couple weeds in my 8'x4' raised bed with 4 inches of pine straw mulch.  I've had it left unattended for five months now, through the spring and summer growing seasons, and it got one weed.

Even if you do, my understanding is that weeds in raised beds get less and less as the years wear on.

I gather that some people intentionally plant nitrogen-fixing cover crops to improve soil health.

Thanks for your feedback, Rob.  I was going to do this based on a recommendation from a master gardener in the area who has a large market garden, but you make a good arguement not to use black plastic.  I didn't know that about worms...!

I have seen where market gardeners use heavy duty silage plastic over last year's crop residue.
I think it might let water in.
They end up with well composted biomass and  bunch of earth worms.

I just "harvested" my pitiful corn bed.
We prepared the bed well but never weeded.
After gathering a bag of tiny twisted cobs for the chickens,  I covered the whole thing in cardboard.
I plan on planting  cold weather greens into the cardboard, at intervals.
I probably should have cut down the plants first,  but I didn't have the time or ability that day.

Well, i am not a master gardener by any stretch so do what feels right to you in your circumstances.