Question
I live in the Northeast and I am a devoted ORGANIC grower.  Most of my plants are vegetables but I do have a lawn and I would like your advice about how to control weeds within the grass.  I use fabric covers between rows in the back, but this is not an option for the lawn.  Any other ways to do this?  I noticed your organic approach to killing quackgrass, although I don't konw if this is one of the weeds or not.  Thanks for all your help.

Answer
So you want to wipe out the Weeds in your Lawn's cool season Grass?

Good news!  There are LOTS of things you can do to wipe out Weeds without turning your Lawn into a Superfund Site.  Have a seat.  Pour a cup of coffee.  This is going to take a few minutes.

Rule Number One: Mow, mow, mow your Lawn.

The Better Lawn and Grass Institute
(www.turfgrasssod.org/lawninstitute/guide.html) points out: 'Proper mowing, watering, and fertilizing practices develop a lawn that needs less chemicals to control Weed, insect and disease problems.'

Almost seems too good to be true.  But just by mowing your Lawn right you will mow those Weeds into the ground.  That means mowing often, and mowing at the right height, at the right time.  Mowing invigorates your Grass.  It's like giving your Grass a massage.  It's GREAT for the roots, and it's a BIG BAD HEADACHE for Weeds.

Let's talk about height.  University of California at Davis did a little research on this.

They concluded at the end of their study: 'No single height is best for all turfgrasses... Each Grass species will be healthier and have a deeper root system the higher the Grass is mowed.'

You can read all about it at their website:

http://anrcatalog.ucdavis.edu/pdf/8006.pdf

The Yardener's Advisor Newsletter posts their advice in 'Mowing The Southern Lawn':

'Routinely mowing southern turfgrasses such as Bermudagrass and Zoysia to a minimum height of 1 1/2 inches reduces Weeds because the longer blades block sunlight that ever-present weed seeds in the soil need to germinate.'

Full text at:

http://www.yardener.com/MowingtheSouthernLawn.html

Most industry data will advise you to keep Bluegrass, Perennial Rye, and Tall and Fine Fescue mowed at 2 inches.  Zoysia should be kept lower, 1/2 to 1 1/2 inches.

The Lawn Institute has advice about the best mowing
heights for all types of grass:

http://www.turfgrasssod.org/lawninstitute.html

That may not sound very important, but the height of your Grass will dictate how much Photosynthesis is taking place on your Lawn.  This is not a cosmetics exercise.  The right height will build healthy Grass that will out-wit Weeds
-- especially some of the newer Grasses.

During Summer Drought and Heat spells, mow a half inch higher.

Cool-season Grasses grow SLOWLY during the heat of Summer.  Plan on doing most of your mowing in spring and autumn.

But watch the height of the mower.  Mow too low and you let lots of light down to the Weed zone.  Bad for Grass.  Good for Weeds.

Yardener's Advisor concurs:

'Increasing the height of your Grass only 1/8 inch adds about 300 additional square feet of leaf surface for each 1,000 square feet of Lawn.  The extra leaf surface enhances Grass growth above the ground and -- even more importantly -- under the soil.'

There are some tough, aggressive Grasses out there that will put Weeds in their place.  Think about that toward the end of the summer, when it's time to start sowing Grass.  Over-seeding is one of the best kept secrets of a superior Lawn.  I recommend some White Clover in any seed next time.  White Clover POURS Nitrogen into the soil.  And it's pretty and it smells sweet.

Nitrogen is actually another one of your best weapons for whacking Weeds.

Surprised?

University of Illinois tested the effect of Nitrogen at different rates on Tall Fescue:

www.turf.uiuc.edu/research/summaries/1994/94_3.1.pdf#search='university%20test%20mowing%20height'

The results posted:  Weed counts 'were greatest in Tall Fescue maintained at a 1 or 2 inch mowing height.'

And they also noted: 'Crabgrass populations increased as mowing height decreased.'

Cool, eh?

When it came to fertilizer, the amount of Nitrogen was not what mattered -- just as long as some Nitrogen fertilizer was applied.  Putting down NO fertilizer yielded the worst results: 'Tall Fescue that was not fertilized had significantly higher broadleaf Weed populations than turf
not fertilized with any Nitrogen.'  Remember, Corn Gluten Meal will slow-release the best Nitrogen money can buy all summer long.

Researchers also noted: 'Even a low annual rate of Nitrogen fertilization can decrease broadleaf Weed populations and reduce or ELIMINATE the need for herbicide control.'

Let's read that again: '...ELIMINATE THE NEED FOR HERBICIDE...'

That's a study the Scotts people won't want you to know about.  What would they do if everybody stopped spending billions of dollars a year on weedkiller?

So, even though you did not mention the name of your Grass,
I think it is safe to say you have all the tools you need here to create the Lawn of your dreams this Summer.  And it won't break the bank.  Which is always nice.

Thanks for writing.  I would appreciate your rating me when you are done here -- I am hoping for an AllExperts of the Year listing at the end of the year and if you Nominate me I will get a little closer to that goal!