Google "lasagna garden". Exactly what you want to do.

What you are planning is not really compost but thick organic mulch. It will decompose eventually but it will take time since it's going to be a cold process and mixing is not that important. My compost pile doesn't heat up unless it's almost 4 ft. tall and wide.

I would remove any artificial weed barriers, cover the area with wet newspapers or cardboard, and spread loads of organic matter on top of it. By the end of summer the weeds will be dead and the paper will be almost broken down, so you can dig in shredded autumn leaves and let that sit over the winter.

If your flat layer approach heats up to the requisite range (131-170 deg F), you will have accomplished both goals — making compost and killing weed seeds. The conventional volcano shape is preferred because it promotes a hot pile. Are your weeds annuals introduced as seeds, or are they perennials that invade your veggie plot from adjacent areas?

I think most of the weeds are annuals from neighbors yards. Some are perennial and give me problems every year.

Since the plot is not being used now I may just spread some paper and clippings to keep weeds down and start a volcano shaped pile if that works better. I have access to lots of newspaper and cardboard but not leaves till fall, can sawdust from untreated wood be used as well?

Yes, you can use sawdust. It may compost slowly and has a tendency to compact so that not much air gets in, so turn frequently or mix well. The issue of nitrogen being 'tied up' could be noticeable with sawdust if you intend to dig it in - you could add urea or other nitrogen source to sawdust pile, or just make sure it's well composted first. If sawdust just spread as a mulch, won't be an issue - okay to eventually dig in (no simple rule for when it's okay to dig it in, depends on a lot of other factors, but the closer it looks, feels and smells like compost or earth, the better).

I think coarse wood chips or newspaper sheets weighed down with stones/bricks are far better than sawdust for weed control.

I call it sheet composting. When it gets thicker than mulch and there's no plants to mulch around, just a layer of compostables on a bed, it's no longer mulch but a flat compost pile. :-D I've done it with garden beds that are laying fallow, or in the fall to cover bare ground and use excess materials that won't fit in my regular compost bin/pile area.

Sawdust works fine if it's mixed with some greens. It takes awhile but you seem to have some time so go for it. Sawdust is also great by itself for walking paths.

I don't think sawdust is good for weed control - too loose on its own - but if you have it, putting it directly on is fine (ie no real need to compost first). It won't 'borrow' nitrogen from soil below to any appreciable depth.

thank you everyone for your help! I have a steady supply of clean douglas fir shavings from a furniture shop, started the lasagna composting in the old garden hopefully it will be ready next year! I will also introduce some red wiggler worms to it to help it along. I am also using the shavings around the back of my above ground pool to suppress weeds (no composting), will be nice not to have to kneel every other week weeding.

Red wigglers are specifically evolved to like an environment like a worm bin with food waste. I've read here many times from worm experts that they don't particularly like living in the ground and will not survive in the temperate US if placed into a compost pile. Just FYI.

Typically if you build it, worms will come that are already there in your soil, ones that are adapted to the conditions.

Besides most of the decomposition is by microbes and insects. Worms can play a part but they're not essential to decomposition.

I'd say that worm bins evolved to become an environment that (some) red wrigglers like but who knows?

Well yeah, that does sound a little weird, and I don't know where red wigglers are from originally, in terms of climate, or where they found piles of food waste before humans came along. :-D

I think most if not all of the earthworms in North America are actually from Europe. That's what I heard anyway. Which gives further credence to the idea that they are not essential to the decomposition process.

Red wigglers don't have to have food waste. They also like manure. I imagine there has been poo in the world as long as there have been brandlings.

Note that red wrigglers are not heat tolerant, and most decent-sized compost piles easily get to temperatures that are fatal for them. So either keep your piles small (as in, "worm bins"), or turn them regularly to cool them off. Now, since bacterial decomposition goes vastly faster at higher temperatures, it really isn't obvious that you want to keep the piles cool enough to ensure worm survival. I would guess that with sheets of the right thickness, lasagna composting would be cool enough, though.

@tox: I agree worms not essential to decomposition. And I mostly agree that adding some to your garden isn't likely to do much of anything - unless the conditions were good enough, in which case they are probably already there.

Yes, they dont' generally live in 'soil' - but decaying organic matter on top of soil, including pretty thick like a compost pile but also layers like cut grass or leaf litter, is often enough. (They do live in the top layer of soil, but depends of course)

I wasn't sure what you meant by 'temperate' conditions - but if you mean cold winters, they do perfectly well in nature in cold climates. They're just not active in winter. Some die off, but clearly they come back, whatever the mechanism.

I suspect there are a lot more strains than anyone knows about, but one way or another, 'local' compost worms are better adapted to the local environment for outdoor living.

Personally I think heat is likely more dangerous for compost worms, too - but less so from a pile heating up, and more from enclosed spaces like a bin in direct sunlight. Just my experience, but seems to me the worms move out of areas that are too hot as long as they have somewhere to go to, and large piles have edge and bottoms and other cooler areas to which they can escape. (And then move back in when the tasty stuff is warm and partly decomposed).

Anyway, i've had hot piles and the worms return very quickly, but these are all piles right against the ground (where it will be cooler). Anything in bright sun, enclosed, on a hot day can kill worms off fast. YMMV.

That's true, that worms will move out of intolerably hot regions. Of course, that means they aren't contributing to the decomposition in those areas, and that's where the decomposition is going fast.

I think of them as the clean up team that come in after.

Compost worms in truth mostly eat partially decomposed and degraded stuff. Manure especially, or things already decomposed that much, whether by hot composting or time or other organisms. People who grind their food up are just helping that process along too.