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Kill Crab Grass before I rennovate?

Posted by kelly_yard Northern CA (My Page) on
Thu, Jan 24, 13 at 20:10

We are preparing to landscape a yard that has been neglected for decades. The existing "lawn" which is basically a mixture of what grows naturally when watered, has lots of crab grass in it during the summer months. My question is what's the best way to prevent the crab grass from invading our new sod and surrounding planting beds? Should I use a preemergent now and then just till the existing grass before putting the sod in. Or should I not bother and remove the existing grass entirely before the crab grass germinates and then do the preemergent? The people at the gardening store told me I can do nothing to kill the crab grass until it begins to grow in spring? We want to have the new sod in around spring. Any advice greatly appreciated.


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RE: Kill Crab Grass before I rennovate?

If you are going to sod the yard, do it as soon as practical before the crabgrass seed begins to sprout. If your winter is going like ours, you are already too late - my weeds are popping like crazy. Starting with sod almost eliminates the possibility of new crabgrass getting started. If you were starting seed in the spring, then you are guaranteed to have a full crabgrass lawn by July. The best time to reseed is in fall or late summer.

Where do you live? You'll have to be more specific. Since you said NoCal and since most of the population that thinks it is in NoCal lives in the Bay Area, I'm going to assume you live there. But if you live inland towards Sacramento, then your exact location becomes more important. If you are on the bay, then you can get away with cool season grasses like fescue and Kentucky bluegrass. IF you are inland where the temps get to the high 90s, then you are in warm season territory. You'll want either bermuda sod or St Augustine.

NEVER ROTOTILL soil in preparation for grass. When you rototill there is no way to keep that machine from gouging deep into the soil and bucking over tree roots, rocks, and just tougher soil. What you end up with is a level surface on top but an uneven surface under all the fluffy soil. When the fluffy soil settles, it settles to the uneven surface below. That leaves the surface uneven and you will want to level it. Just start with a level surface and you will be 3 years ahead.

When you install the sod, be sure to roll it down with a rented, water filled, roller. Grass roots will not grow through the air to reach the moist soil below. You must have good sod to soil contact. If the area is small you can just walk over it as long as you hit all of it.

Here is the 1-2-3 of lawn care. It's really this simple.


  1. Water deeply and infrequently. Deeply means at least an hour in every zone, all at once. Infrequently means monthly during the cool months and no more than weekly during the hottest part of summer. If your grass looks dry before the month/week is up, water longer next time. Deep watering grows deep, drought resistant roots. Infrequent watering allows the top layer of soil to dry completely which kills off many shallow rooted weeds.

  2. Mulch mow at the highest setting on your mower. Most grasses are the most dense when mowed tall. Bermuda, centipede, and bent grasses are the most dense when mowed at the lowest setting on your mower. Dense grass shades out weeds and uses less water when tall. Dense grass feeds the deep roots you're developing in 1 above.

  3. Fertilize regularly. I fertilize 4 times per year using organic fertilizer. Which fertilizer you use is much less important than numbers 1 and 2 above.

If you are not going to use organic fertilizer all the time, I strongly suggest you use it one time per year at a rate of 20 pounds per 1,000 square feet. Your soil microbes cannot live without food. Organic fertilizer is the food they need.


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