From what you describe, the lasagna method might be preferable, but I would do at least one bed built from purchased soil and compost. You will want to cover the ground well with some kind of barrier to prevent the existing vegetation from growing up through your beds, cardboard and multiple layers of newspaper are favored materials. You should start accumulating lasagna materials now, and if there is not too much snow on the ground, could in fact start the building process. The "green" material will likely freeze, and therefor remain "green" until warmer temps allow the decomposition process to start. In the lasagna beds, you will be able to grow tomatoes and squashes (and some other things) without having to incorporate much actual soil, they can survive the processes of decomposition going on below them, The beds built with soil and compost will be better suited to those crops that require a more mature soil, and those that prefer a finer tilth... salad greens and root crops spring first to mind. Other plants might be most advantageously started in pots until the lasagna beds have reached a stage of decomposition that is less injurious to tender roots. The pots could be situated in areas where you plan future beds, thus providing a way to kill the existing vegetation in the soil beneath them without having to dig (which you seem to want to avoid) or sacrifice ground. There are big differences between (and among) purchased composts and soils. Be careful that what you are buying is truly what you want. You don't need a lot provided your native soil is relatively healthy, though the texture may not be ideal. If you have a native population of earthworms, they will eventually create the soil you will benefit from most, if not, introducing them, from a near-by source, when you start your beds, will go a long way towards creating better tilth. And skip that liquid stuff for now. If you want to buy something in a bottle for your garden, I'd recommend a nice crisp white to accompany the salads and grilled veggies you'll be enjoying this summer.

I gardened in SF clay for decades so I know what you're talking about. You cannot work California clay in January. That is the rainiest month, and right now you've gotten huge amounts of rain even for January. Wet clay should not and cannot be worked. I never planted anything in the ground (pots only) in December or January - the clay is too wet and too cold. A planter box should have purchased soil mix in it. Not clay. The comment about using plastic is to protect soil about to be planted in from getting excessively wet. Not for the whole yard. I would instruct my clients to tarp the area they wanted me to plant fruit trees in so it would be workable. Once clay is wet, you have to wait for it to drain a few days before you can work it. (Hence the tarping beforehand.) Squeeze a bit in your hand. If it squeezes through your fingers and remains in one piece with ribbons sticking out where it came through your fingers, it's too wet. It should crumble at least a little bit before you try to work it. When it's dry enough, compost is the best thing. Gypsum does not work in California clay. You will not transform it overnight, or even in a year or two. It will always be clay, and that's not a bad thing - I miss clay. Here I'm gardening in dirty gravel, with no water retention or nutrient retention or any measurable organic matter. Most trees and shrubs will grow in clay just fine, with annual additions of a little compost. Lettuce and other vegies are a different story, they need a looser soil. That's where mounding up amended soil comes in. Dig up the clay, add some compost and maybe some purchased topsoil, and mix it all together and heap it up above grade. Don't just lay stuff on top of the clay and then plant in it, as water will sit on top of the clay and the plants' roots will then be sitting in water. Mix it up so it grades from amended soil to the native clay. Compost helps any soil, clay or sand. You just can't work clay soil after all that rain you've gotten. You'll have to wait for it to dry a bit.

Try using red or white clover in your garden I have observed that grass wasn't growing near a part of our yard where we grew melons and watermelon so this year as an experiment we our going to thow white organic cloverseeds in our vegetable garden It is supposed to also fix nitrogen in the soil just as beas when planted with corn as Squash shades and protects of what's known as The Three Sisters.Oh White clover is supposed to be a good grass suppressor prevents grass from growing just whats needed in our garden.First we did a layer of 3 layers of the white ink less news paper wet it all down with our iltered garden hose then put cardboard around the whole garden fence then wet that down too alk done o a non windy day topoed with cow manure and some chicken manure then we put 3 inches of woodchips or woodchip mulch last year in the Spring but all that should have been done in the Fall! This year we are not planting plants but Only Organic Heirloom seeds and some Organic plants howeveryou need to keep tge woodchips away from the stems and keep around the drip area only! Put Toilet paper rolks around seedlings to prevent cutworms thise white cabbage montths lay.Spray aroundfir ticks aunts red yes and fleas Use Garlic online stuff I'll get back you thx medicine

What is SAYS in the bag is much less important than what is actually IN the bag. To growing strictly in compost of mixes made of of very large fractions of compost is to unnecessarily saddle oneself with a difficulty factor best avoided. The reasons: 1) Water retention is based primarily on the size of the particles that make up the substrate. All small particles, as in "finished" compost, and the medium is sure to hold too much water and too little air; and, much of the excess water will be held as perched water. This ultimately means north of 3" and up to 6-7" of the soil in the bottom of the pot will be 100% saturated after a thorough watering. This means that for extended periods the planting will be subjected to limitations imposed by a lack of oxygen. Lack of oxygen kills fine roots, which halts top growth until new roots are again capable of regeneration (requiring a draw down of the level of water in the pot). Regeneration of new roots requires resources that would otherwise have contributed to adding more biomass, blooms, fruit, stored energy. Unfortunately, about the time the root to shoot ratio has come back into balance, the grower is usually watering again, which begins a repeat of a cyclic death/ regeneration of roots which can rob plants of immense fractions of their genetic potential. 2) IF the compost is in larger pieces (not finished), expect an unmanageable (or nearly so) level of nitrogen immobilization. Then, if something cultural occurs to kill off the large populations of soil biota (like over-watering or high soil temperatures, insecticides making their way into the soil) associated with nitrogen immobilization, look for ammonia toxicity to make its appearance. It is SOOO much easier if you start with 75-80% of coarse material (>1.8") and add only enough fine material to adjust water retention to something you can live with. Do understand though, that when your watering intervals start to stretch out to beyond 5 days, you'll be sacrificing a notable measure of your planting's potential on the altar of convenience. If you can measure your watering intervals in weeks instead of days, an immense amount of potential in terms of growth rate, vitality, the plant's ability to defend itself, and yields where applicable, has almost certainly been lost. Al