Depending on the grass a good mulch might work on the wimpy but desireable grasses many of us prefer, the Blue grasses, Perennial Ryes, Fescues. But for the more aggressive, and invasive grasses, a mulch will only provide a good growing media, moist, enriched soil. The best means of eliminating grass from a planting bed is to mechanically remove it, roots and all, and then put a physical barrier in so the grass cannot grow back.

My oldest son actually did a comparison of a few homemade weed killers for a middle school science project a couple of years ago. Straight vinegar was only moderately effective. It did not kill roots, so any weed capable of resprouting from the roots (grasses, dandelions, perennial weeds) came right back. It did kill some of the annual weeds, though. We also tried boiling water, which was more effective. It still didn't kill off grasses or other deep-rooted weeds - at least not with the quantity of boiling water we were able to carry to the yard. Boiling vinegar did better, killing most of the dandelions, but the grasses and some of the perennial weeds still came back. (Note: a big pot of boiling vinegar is no fun to carry across the yard. The things we do for our kids...) My experience has been that to kill grasses or perennial weeds, you really have to pull/dig up the roots completely or use Roundup. Soil solarization works pretty well for annual weeds, but grasses will still come back because solarization only heats the soil to 6"-8", and grass roots can be considerably deeper. You can also cover the ground with a thick layer of cardboard (covered with a thick layer of mulch to keep the cardboard in place) and smother the weeds. This works, but the grasses and weeds will find any spots where you didn't adequately overlap the cardboard.

Sorry. This will be a long one. It always is with me. (blushing) I'm with the OP on this one. Even if no one but me ever saw my lawn, I would want it to be dark, rich green GRASS...and nothing else. (I'm known for wanting everything to be beautiful. I'm also a bit of a home body, and enjoy spending time in my yard. Many guests have remarked that, no matter where they look (on my property), there's always something beautiful. I'm always taken aback by those comments, since while that was MY goal, I never expected others to pick up on it.) Case in point about the intentional act of putting down grass, and not other (lower maintenance) plants. I own a small, remote island. I made the decision to create a lawn area and, once you include the slow-moving barge fees (3 days to get from its port to the island), labour, equipment, and materials, that lawn cost me $14,000. That obviously begs the question, why, on earth, would anyone spend a nickel putting in expensive, high-maintenance grass, only to let it be taken over by clover and other weeds??? My husband and I recently purchased a 19th century farmhouse in need of roof-to-foundation renovation. As such, I inherited a lawn that is EASILY 70% weeds, including clover so thoroughly interwoven, it would be impossible to pull by hand. I pride myself on my beautiful lawns and gardens, and can spend/have sent hours, each day, ensuring everything is healthy and how I want it. At my last home, I developed a bit of a reputation for being out weeding my lawn by hand for hours, plus how awesome my expansive lawn was. My point is, I want my lawn and gardens to be a certain way; plant the plants I want; pull the plants I don't want; unafraid to put-in the effort to achieve that. I prefer not to use any kinds of "chemicals", other than the ammonia and mild soap I include in my homemade fertilizer recipe. (My last home was a beach house. So, that only reinforced my desire to go chemical-free.) But this new-to-me house is demoralizing me...practically to the point of tears, much of it because of the state of the (laughing) "landscaping". Sure, mowing can cut off 60% of the sea of clover flowers that make my lawn look white (or dying...can't decide which). But there are still lower flowers that seem to sprout up to full height within the next 24hrs after a mow. These flowers last from late spring to fall. In short, I'm plagued by clover flowers throughout the entire season I want my lawn to look great. It's just such a shame the previous owners didn't nip the clover in the bud, when each plant was jut a little, round cluster. I love catching them early, knowing I've stopped additional infiltration. But I'm helpless, overall. Looks like I'll have to replace the entire lawn; start from scratch; do what the previous owners SHOULD have done, and pulled weeds when I first see them. I'm not really buying the whole "benefits of clover" thing, amidst a grass lawn. If I wanted a clover lawn, I would plant a clover lawn. Putting down and maintaining grass is an expense in time and resources. Clover is virtually free (since it shows up on the wind), and is seemingly mantenance-free. Since most sod and grass seed are sold with some guarantee of being weed- (and clover-) free, I just don't believe that most people who spend the money and effort to put in a grass lawn, are okay with losing any percentage of it to other, invasive, undesirable plants. I kind of liken it to suggesting that a Ferrari owner would be okay with someone switching it with a Cavalier, and just saying, 'They both get me from point A to point B, so I don't mind.' I can fully envision putting in other kinds of ground cover, and have considered it at past properties. Not being my first rodeo, I already have substantial plans to reduce the amount of lawn area, and increase planting beds. But much of this current property begs for a beautiful, thick, dark green lawn...of grass. No dandelions. No clover, but particularly no clover flowers. (I'd be more okay with clover, if not for the flowers.) The desperation was so great, I did something I thought I'd never do, and tried the iron-based WEED-B-GONE product. (Harsh, chemical herbicides have been banned in my area for years...resulting in public parks being taken over by weeds, for the most part. It's such a shame, in the sense that a healthy, well-maintained lawn is not only beautiful, but fantastic underfoot.) That is really my philosophy, beyond the aesthetic. A lawn should be cool, soft, and luxurious under bare feet. Weeds, even overgrown grass, also tend to make barefoot walking less than a joy. So far, I haven't found a way to get rid of mats of clover. The WEED-B-GONE did nothing I could notice. I'm at my rope's end on ths matter, and likely will have to pull up the entire lawn, to put down new, almost-weed-free sod, where I can physically manage pulling individual weeds as they appear. I guess I'd plead with people to pull unwanted clover plants when they're small... if not for yourself, then for the next property owner. Sure, it means time, every day, or every few days, combing the lawn, looking for weeds. Yes, it can be back-breaking and time-consuming. But that grass lawn didn't get there by accident. A grass lawn is intentional.

This article called “PREPARING A LANDSCAPE SITE WITHOUT CHEMICALS” describes step-wise detail from planning to successfully installing the turf without any chemical in your lawn. And here you can get all the details about common weeds and how to eliminate it naturally. https://www.abchomeandcommercial.com/blog/how-to-get-rid-of-weeds-without-killing-grass/ And for your Oxalis problem, this is what you can do to get rid of it without using chemical: Spray the oxalis with a homemade non-toxic weed killer. Fill a small spray bottle with white vinegar and add one or two squirts of dish soap. Gently shake, then spray the mixture directly on the base of the oxalis clusters. This works even better on a hot day. The foliage should be dead within 24 hours. Things You Will Need Hoe or spade Scissors or garden shears Plastic bag Spray bottle White vinegar Dish soap Tip Oxalis flowers, seed pods, leaves and stems are edible in moderation. Those with kidney stones or gout should avoid it, as they do any food (such as tomatoes or spinach) with oxalic acid. Warning Do not spray homemade weed killer on any plant you wish to keep; vinegar kills any plant it touches.