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Now is the Time For All Good Gardeners To Come to the Aid of Their Bluegrass!


Q. Mike: We built our house four years ago. At first, we actually had some "grass", but the red clover, crabgrass and other weeds have since taken over. I know that you always say to plant in the fall and treat for weeds in the spring, but I am really tired of the poor quality of yard we have and want to do something now. Could you tell me the best plan for a large yard? Thank you,
    ---Kate in Exline, Iowa
My front yard has developed a crabgrass problem. My lawn care provider told me it was because of the intense heat we've had this summer. Is it too late to do anything? Or do I have to look at crabgrass for the rest of this year?
    ---Ken in Triangle, VA
A. Weeds typically get their best shot at overtaking Northern lawns at this time of year, and it pays to understand the mechanisms by which this happens—and what lawn owners often do to unintentionally make the problem worse.

Cool season grasses—bluegrass, rye and the fescues—love the weather of Spring, Fall and winter because they're native to cooler parts of the world. The warm season grasses—like centipede, Bermuda, zoysia, and St. Augustine—come from more tropical areas and like it HOT, thriving in the heat of summer.

The cool season grasses favored by Northerners are at their weakest in the heat of summer, and so their tendency is to go dormant and send their energy down to hide in their roots, which often causes a temporarily browning up top. The lawn owner rarely agrees to this natural protective response, and instead tries to 'help' with salty chemical fertilizers and short cuts, both of which release the stored moisture in the turf.

Thus the despicable grass rewards the intended kindness with bare spots; allowing free entry to the crabgrass and other warm-season annual weeds that have been waiting patiently for the homeowner to hand them an easy victory.

If you feed a cool season lawn in the summer, you are working for the weeds. If you cut a cool-season lawn below three inches or cut it at all during a dry heat wave you are working for the weeds. And if you hire a lawn care provider to do these things for you, you are paying someone else to work for the weeds.

Want a relatively weed free lawn? Stop killing the lawn!

Never cut cool season grasses below three inches, apply corn gluten meal in Spring to feed and prevent dormant weed seeds from sprouting, feed again naturally in the fall, and don't stare at the poor thing during the summer. People with zoysia grass lawns don't even notice when their grass goes tan and dormant for months in the winter; so maybe you shouldn't call the police when your cool season turf tries to take a five-minute nap during a record breaking heat wave.

What can you do now? Have a big load of compost delivered and rake it into the lawn. (See this Previous Question of the week for help in locating the right kind of bulk compost.) Compost provides a better feeding than 'traditional' lawn chemicals, and puts some much needed life back into your soil. If your lawn is a spreading turf like bluegrass, small bare spots will fill themselves in. If it's a clumping grass like fescue, you must fill in the bare spots with seed that matches the color and blade shape of the existing turf. And yes, if you have big clumps of crabgrass that you're going to insist on staring at, you can dig them out first.

But if your Northern lawn is more than half weeds, follow the sage advice of Iowa State turf grass researcher Nick Christians and sow a new one--now. Sowing cool season grass seed between mid-August and the end of September virtually insures long-term success. Here's the step-by-step plan:

  • Till up what you have.
  • Rake away as much of the old green material as possible.
  • Level the surface, water well and wait a week.
  • Then destroy any new weeds that sprout with a sharp hoe pulled lightly across the soil surface. If there's a lot of lawn, hire some help or do the hoeing in stages. Don't use herbicides.
  • Then apply a one-to-two inch layer of compost on top of the 'stale seed bed' you've created. Do not sow new seed on top of your terrible existing soil; that's why your old lawn looked so bad!
  • Level the surface perfectly. An uneven lawn will never look good.
  • Sow your new seed into the compost and rake gently until most of the seed is no longer visible. Don't smother the new grass with straw or other nonsense.
  • Water gently every day for a week to keep the seed moist. Don't water on days when it rains.
  • Then cut back to every other day for a week. Then twice a week. Then once a week. Less if it's cool and rainy; more if it's hot and dry.
  • If deciduous trees are nearby, shred any leaves that fall on the new turf directly back into the grass with a mulching mower; or suck them up with a blower-vac. Don't use a rake on new grass.
Now, if you have—or plan to install—a warm-season grass, none of this applies to you. You warm weather folks plant in Spring and feed in summer.

And if this does apply to you and it's a huge lawn, don't take a lot of shortcuts to get it all done right away. Break the job up over several seasons, starting with the areas you use most often. Don't attempt to do more this fall than you can do well.

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