Keep in mind that "weeds" grow from seeds and you probably have a million or more "weed" seeds in your soil just waiting for the right conditions to germinate. Rather than expend so much time and energy trying to "eliminate" those "weeds" why not expend that time and energy on growing a good, healthy turf that will cut down on the "weeds" you have for you. While many "weeds" will grow in the soils turf grasses do they can be indicators of soil related problems, wrong soil pH, nutrient imbalance, moisture problems, etc.
In addition to having a good, reliable soil test done, I understand AgCanada does not do them but they should be able to direct to someone that will, for soil pH and major nutrient levels how much organic matter is in your soil?
How well does that soil drain?
How well does that soil retain moisture?
What kind of life is in that soil?
What does your soil smell like?

Thanks very much for your reply. Please help me to understand a bit better what you are saying - I'm a newbie gardener.
1) Yes, you acknowledged a couple of days ago that I do have clay soil. I attached a picture of my jar test (mostly goop with clear water on top). I explained that I have clay and rocks under my thin layer of topsoil. While I might not have much organic material, I do have LOTS of worms, and one of my priorities is to protect them.
2) There's an accredited lab about 40 minutes from my house. I'll drive a soil sample over there when they open on Monday.
3) My backyard is mostly bare patches and weeds. I assumed (maybe incorrectly) that the weeds are multiplying because they are opportunists. When there are bare patches they'll move right in. Also they throw their seed faster than grass spreads (some grass does not spread at all), so it's a constant battle. So I think I hear you saying for me to increase the amount of grass I have because if I have grass instead of bare patches, the weed seeds will have much less opportunity to root.
4) However, right now I feel like I'm fighting a losing battle. I'm attaching a picture of the little sprouts (thousands of them) that are now sprouting up all over the bare patches in my yard. The grass seed is not growing yet, but these weed sprouts are. So where will these 10's of thousands of weeds (the new ones plus the big old ones) go if I don't try to kill/smother them?
5) Are you saying that once the grass starts to grow the weeds will die? Or are you saying I should live with the weeds?
6) The theory that watering deep and infrequently will cause weeds to shrivel up and die doesn't seem to hold true for my clay soil. I've been pulling out dandelions and most of the taproots are 10" long. So even without any watering (on my part), they managed to flourish.
7) In a situation where I have predominently weeds, is it possible to turn it around so I have predominently grass, without actively killing the weeds somehow?
Please help me to understand. I really want to learn, so I can understand how this all works. Thanks for your help.

This post was edited by ARiverRuns on Sat, May 4, 13 at 14:44

Once the soil is made into a good healthy soil your turf grass will have a better chance to grow and as it fills in the grass will shade the soil so "weed" seeds will not germinate as readily. In our area of the world the best time to seed a lawn is early fall, not spring, so the grass has a chance to get established before the hot, dry summer creates problems for these cool season grasses.

Thank you for your patience - I think I finally get it. If I spend my time chasing weeds, I'll forever be doing that and making no progress. Instead, if I spend my time amending my soil, I'll be improving my grass AND decreasing my weeds.
Also, if I were to cover my lawn with newspaper or cardboard to kill everything, I would not be able to work on amending the soil this summer. So thank you for your advice.
Here is my plan - please let me know if I've understood all of this correctly, or if there are some points that need correcting:
1) I can pull the flowers off the dandelions and mow the tops off the other weeds to prevent them from spreading.
2) I'll amend my soil, based on the results of the soil test I'm getting tomorrow.
3) I'll try to get some municipal compost now and every spring.
4) I'll mulch my grass clippings and fall leaves.
5) I'll add organic protein based fertilizers (alfalfa pellets, corn meal, used coffee grounds, or soy meal) every few weeks throughout the growing season, as the lawn is able to absorb it.
6) I've read that sugar and/or molasses is also good for feeding the soil and keeping back weeds, so I'll apply that every spring and fall.
7) I'll mow high to keep more weeds from taking root.
8) I'll water infrequently and deeply (in the mornings), to encourage the grass to grow deeper roots.
9) I'll overseed in late summer every year.
10) I'll use corn gluten meal as a pre-emergent every April before the new weed seeds start to sprout.
11) QUESTION: I have some bare patches now. I think I just missed the window for corn gluten meal to be effective this year (because it's already May). Should I put some grass seed on those bare areas now, in order to try to keep more weeds from moving into those areas?
12) QUESTION: Because it's clay soil (and holds water and footprints) I have lots of dimples in my lawn. Can I level it with coarse sand this summer, or would the sand interfere with all the work I'm trying to do to improve the soil?
Thanks for all your help - I really appreciate it.

This post was edited by ARiverRuns on Mon, May 6, 13 at 10:07

I'm in Oklahoma (zone 7a) and I am in the exact position you are! Drives me nuts to see the weeds in my front lawn (if you can call it that). I, too, am doing the things that you have outlined, hoping for happy and healthy soil (and happy and healthy grass to follow).
I experimented a little last week when we had sunshine, and straight vinegar is great for killing simple weeds. I have tough Dallis grass to deal with, so it may need a different attack. Bear in mind that the vinegar will kill anything it lands on, good grass included, so painting it on some of your weeds (or spraying it on a sidewalk or driveway, etc.) may be a better thought. I have yet to try boiling water.
Good luck! I'll check back periodically to see how you're doing.
Sharon

Thanks for your encouragement Sharon.
Seriously, if somebody could guarantee me that vinegar would not hurt the worms, I'd spray vinegar all over my entire lawn and start again - there's not much grass worth saving.
My soil test came back yesterday and my soil seems pretty good - they just recommended a 21-7-7 fertilizer - nothing else needs to be added.
I had read that weeds often take over when the soil is unhealthy, when it is way out of balance, and that by correcting the soil imbalances, the weeds start to fade away. But this doesn't seem to be my case - it looks like I'm stuck with these weeds (and I'll even be fertilizing them, the irony of it all).
I've mowed as low as I can go (to get the dandelion heads off before they go to seed), yet I still have a couple of thousand new dandelion flowers pop up every day that are below the lowest setting on the mower (not to mention the other weeds that are multiplying as well). I'm at a loss as to how to get rid of them all.
I'm really frustrated with all of this.

Raising your mower height to it max level is one of the best defenses against weeds. It's also beneficial to soil (extra shade for SFW to thrive). But as your lawn thickens, the upright growing grass will out crowd weeds, many of which tend to grow more horizontally than vertically.

It still takes time and results are visible but will become more clear as you overseed each fall. In mean time you can weed, dead head, and apply vinegar. And to answer your question on that: I don't think that vinegar is harmful to worms because a) your only spraying enough to get it on the foliage, that's where it hurts em most. b.) your applying it on any warm days, so most of it evaporates which kills the plant. Really works :D

ARiverRuns,

Some of the advice you are being given is altruistic but not practical. Regardless of how great your soil is, or how well you practice good lawn care (proper application timing of pre-M/ferts, infrequent deep watering, keeping the grass high and cutting frequently to remove only 1/3 blade height, etc.), if you have a "lawn" with little to no grass it will not matter.

If you started with a great lawn, a good lawn, or a semi-decent lawn, yes, you can amend through the above practices to get a better lawn/ecosystem. But with many people's lawns the best investment of time/money and the most rapid "success" (which is in quotes because you have to define what success means to you) is with a fresh start.

You can Round-Up (oh my God I said it in the Organic forum!), you can burn it, you can use any "less toxic" chemical or spray (vinegar, which I don't like since it only kills top growth of a weed), or simply cover it with any substance that will prevent proper light/moisture/air transfer.

You can go from non-organic, to organic AFTER getting an established lawn, or you could spend a fortune and demo the whole lawn and put down beautiful sod that would look great tomorrow.

Now to your specifics:

-carpet is probably NOT a good idea. Chemicals depending on the composition/backing of the carpet would likely leech into the soil due to UV exposure and rain. I can guarantee you this would be worse for the ecosystem than just burning the yard. It is also likely you could sprout weeds IN the carpet depending on the weave, not to mention the very likely mold/fungus that will survive in a wet carpet (removal at the end of the summer would be horrible).

-A plastic tarp for a couple days (when sunny) is a much faster method that should not harm the worms appreciably (they'll burrow down to avoid the warm temps under the tarp).

-Cardboard method from your original list is IMO the best option (though you should know that cardboard is not necessarily a clean product depending on the source as adhesives are sometimes used), the paper used itself in the construction can be bleached/treated, anything printed on the cardboard could have unfriendly inks/dyes, and honestly it's too thick in most applications for a quick kill (weeds) and then decomposition. But a thinner decomposable paper would work likely as good.

And it doesn't matter if the weeds are truly dead or not. They will be weak or outright dead from the lack of sunlight/air, and if they get through the board and soil they will struggle to get enough sunlight in a stand of thick sod (cut high).

So to sum up my personal recommendation:

Get some large plastic tarps and several days prior to the sod arrival put them down (and hope for sun). The day you get the sod remove one of the tarps, put down some good compost/top soil, properly install the sod (this is KEY for its survival), apply a fertilizer, top dress with a VERY thin layer of compost/soil, and then press the entire area with a water roller or some other object that will remove air between the layers. Then water WELL, and give frequent short/moderate waterings for at least a couple weeks (especially during mid-day when stress is at it's highest, don't worry it's a myth about watering during the heat/sun of the day). Tug an area every couple days after the first week to see if the roots are setting and then you can water less frequently. Mow as HIGH as your mower will allow.

The worms will thank you for the new home.

HTH

Weeds mainly grow from bird excrement, wind blowing, and even us, I know right? If you could mow before weeds mature, than you're fine; however, if you don't the mower blades will blow [throw] seed across your lawn.

Anyone that thinks the use of any glysophate product, or many of the other general "weed" killers is not an organic grower.
Establishing an organic lawn might be a bit more work then a "conventional" lawn but in the long run it is less expensive and easier to maintain. Perhaps this from Growing a Greener World will be of some help.

Here is a link that might be useful: GGW 305

.......Is what? I'm sorry your first sentence is missing something. Safe? Effective? A Purple Elephant?

What I said was there is no black and white line, you can use a process that is not "organic" to get you to a point where you can exclusively be organic. If I use only soybean meal on my lawn but spot-sprayed RU 5 years ago to kill off some trouble weeds is my lawn organic? I'm sure you would say no but most would not have the same opinion.

I'm trying to help the OP get a good looking lawn QUICKLY with as minimal damage to the worms so they can appreciate all the hard work that was spent getting it that way. Spending 2-5 years or hundreds of hours of labor is just not in most people's plan. And what I find is people that want to go organic are normally turned off and go completely chemical (lawn service for instance) if they can't start with a good turf or get it good in a single growing season.