Organic weed control?
 

My efforts at green lawn care in 2010 had mixed results. Nitrogen application caused my grass to handily outcompete the clover, and the non-clover weeds in the front lawn were eventually taken care of with intelligent manual weeding. The grass was kept healthy by regularly mowing high and never watering.

However, the back lawn is still a disaster.
http://farm3.static.flickr.com/2635/...e31be261_b.jpg
Let's call it 20% grass, 80% weeds. The landlord is getting uppity, and wants to apply chemical herbicide. I have no doubt that would be easy and effective, but I'd prefer not to have those products near my house, my garden, and in local groundwater. Sure, local groundwater flows through the city and into Lake Erie, where a few more lbs of herbicide would be a drop in the pail, but still, I'd like to prove that organic methods can be effective. Little success so far. Google recommends manual weeding, but I'd be pulling out 80% of the plants in the back yard. No thanks.

Anyway, I isolated the following organisms, in addition to dandelions and grape hyacinth. Can you help me identify and eradicate them? Except, of course, the third one in, which is grass.

http://farm3.static.flickr.com/2008/...dee4f984_b.jpg

Hey, it's green and it grows well on it's own! They are all plants -- we think of certain ones as weeds; but why worry about it? A diverse garden (in the English sense of the word) is much better for the soil than a monoculture. If it grows without fertilizer (other than compost) and without watering, and it might even not need mowing -- then I say let it grow.

looking at the pictures the top one looks like a strawberry plant.

If you use herbicide it will kill almost everything and you're going to end up with a dirt patch until you reseed the grass. realistically that many weeds in the ground means it's deficient in pretty much all of the major minerals grass needs. Even if you kill the weeds and reseed with grass you're going to need to fertilize a lot to keep the grass strong enough to compete. Personally I'd leave it...

If you haven't done it yet, check your soil pH and adjust it to the optimum pH range for grass, pH 6.5 to 7.0. This would discourage any weeds that prefer a different pH range and encourage the grass to do its best. Use a good quality test setup as some of the el cheapo sets sold in the box stores are less than accurate at measuring pH.

Here's a quick guide to what your weeds are telling you about your soil.
http://www.thelawninstitute.org/educ...=4992&c=186973

Check out Corn Gluten Meal. I haven't tried it, but it apparently acts as a weed suppressor and later a nitrogen boost for the grass.

It won't help this year, though.

The good news is the weeds will soon decline naturally and the grass will increase naturally. Weeds come first, then the grass takes over as they falter and fail. (until next year)

Ideally, I'd never mow. I'd have a pasture instead of a lawn, and goats would provide me with milk and mutton. It's a local source of food and fertilizer, and I wouldn't have to waste electricity on mowing the lawn.

However, people expect to see a monocrop of grass. People don't like surprises, and I want to make a good first impression. Therefore, monocrop it is. Besides, I want to prove that you don't need chemical herbicide to grow a nice lawn. I haven't managed to prove anything yet, aside from how great electric mowers are for small lawns.

Basjoos, that looks like a comprehensive and useful resource. Unfortunately, I don't know the names of my weeds, except for strawberries and hyacinths.

Pale, that looks like a potentially useful herbicide. Another option is industrial vinegar, which burns the waxy coating off leaves, causing plants to dry out. It should double as a soil acidifier, so I may let the results of my pH test advise my decision.

I finally got a reply from my local Extension Office:It all seems logical, though I've heard conflicting advice on point 3. I'll have to overseed half of the lawn, and see which half does better. I hope all their advice is evidence based and has been scientifically tested. The Extension Office is operated by a well-respected university, so I bet it is.

Robert, I've heard that nicotine is a herbicide. I don't know if it will kill grass, though.

Edit: If it's monocrop you're after, then maybe it would be easier to invest in one of the weeds instead of grass?

I'd bet the Extension Office is probably right. I would also suggest finding out which grasses are native to your area. Natives should need less water and fertilizer than the varieties the big box home center sells. Also, planting a variety of native grasses avoids problems of monoculture while giving a more uniform appearance than what is growing in your yard now.

Native Plants – Upstate NY

FWIW,
Tim

Here's another thought:

Do you know anyone locally with a goat? I know this sounds odd, but a goat could graze down the weeds a few times over a few weeks to give the grass a better chance. I've read/heard that goats prefer weeds and forbs to grass. A few grazings (assuming the goat is selective) might be enough help to give the grass a chance.

There is actually a service near me that rents out a herd of goats (with goatherd) to graze down woody brush and similar weeds. The goats leave the grass and pretty effectively manage the weeds.

FWIW,
Tim