help with a lawn question


I'm in central Virginia, zone 7. I'm kind of new at the lawn thing. I planted my first lawn too late this past Spring, and it came in full and lush, but then got invaded by weeds and crabgrass, as I failed to put down preemergent. By now, half the lawn has turned into crabgrass and weeds. There is some grass, however, and I really don't want to retill and sew a new lawn. I'd really like to get rid of the crabgrass and overseed with fescue, but the crabgrass is still green and looks like it's reseeding itself. How should I approach this lawn if I don't want to retill the soil and resew a totally new lawn. I know fall is the prime time to plant grass and I was hoping I could overseed. Will I have to wipe out the crabgrass (which is pretty thick) by using a weedkiller? Is there still time to kill it, seed/overseed and hope for growth? I'd like to do all the proper fertilizing for new grass roots, so it would get nutrients during the winter and come back in the sping. Next spring..if I have grass.I will definitely put down the preemergent!
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cb wrote:

My suggestion, and what I did last weekend just north of you in Montgomery Co. I also have a ton of crabgrass, plus weeds. I was not up for wiping everything out with roundup, tilling, etc. I set my mower at about 3" and cut on Thursday, then lowered to scalping height, about 2", and mowed again Saturday. Followed that with a core aerator, and made numerous passes to get lots of holes everywhere. Then seeded.
I hope to get halfway decent results. I know that slit seeding or power raking is what the pros do or recommend, I was not up for all that.
The crabgrass will die as soon as the weather cools off. It will then come back in spring if you don't do the pre-emergence treatment. I hope to have at least some new fescue grown up in the next few weeks. I'll report back in a week with my results so far.
David in MD
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I'll bet it wasn't failure to use a pre-emergent herbicide, it was failure to cut the lawn correctly, and probably failure to fertilize correctly. You may also have a soil problem, possibly compaction or pH. Your very best "weapon" in keeping down weeds is what the weed science folks call "canopy closure"... getting the crop so thickly growing that the weed seeds either don't germinate, or don't grow.
If you've got clay soils and lots of foot traffic, you probably need to aerate or till or work in more organic matter (my favorite lazy method is to spread compost about 1/4" thick on the lawn, several times a year.) If you've got very sandy soil, more organic matter is also a good idea.
1) mow the crabgrass... don't let it reseed. Crabgrass is an annual, so you don't need to hit it with herbicide now. You may or may not want to use herbicides on your other weeds.
2) get a soil test -- http://www.ext.vt.edu/pubs/compost/452-129/452-129.html
3) fertilize and lime according to your test results
4) scratch up the soil surface and reseed with good quality grass seed appropriate for your location, your soil type, and the amount of sun the area gets. Bluegrass, for instance, likes sun. Fescues tolerate shade better. Buffalograss likes hot and dry. If you need to see green fairly instantly, once you've overseeded with grass seed, overseed again with buckwheat. It's an annual that won't survive your winters, and it'll add a little organic matter to the soil next year. Buckwheat comes up fast (about a week)-- bluegrass takes 14-28 days to germinate, depending on temperature.
5) water religiously till the seedlings are pretty well established. seed that's started to sprout and then dries out is dead seed.
6) consider whether or not you want to use another herbicide now, and if so, what. Many cannot be used while you're getting grass going. If you've got some truly nasty weeds like Canada thistle or quackgrass, I'd probably given them a dose of glyphosate (Roundup or similar), applied when the plants are actively growing. Most herbicides work best when the plants are active, not at all if they're just sitting there waiting for the right conditions to start growing again. In the herbicide world, Timing is Everything. Stuff like dandelions or knotweeds I'd forget about this season, or I'd devote a few evenings after a frustrating day at work to pulling weeds. Very useful therapy. <g>
7) Next year, mow properly. Sharpen the mower blades (torn, rather than cut, grass blades are more prone to infection by various and sundry fungi, and torn blades brown at the tip and look icky). Mow at the correct height, and never remove more than about 1/3 of the grass height at a time. 2-3" is about the right height for bluegrass, fescues and perennial ryegrass (I feel strongly, however, that 3" is better for most lawn owners... the lawn is more weed-resistant). You can mow a little shorter in the spring, a little longer in summer's heat. But don't scalp the grass, and don't remove more than 1/3 at a cutting.
8) Fertilize and lime as soil tests indicate.
Kay
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You can also pull out patches of crabgrass with the Ergonica Weed Twister. On the weedtwister.com website there are photos of the Weed Twister vs. Crabgrass.
Crabgrass seems to be a bigger problem this year than last. Part of the problem is that most people don't want to face the challenge of uprooting this runaway weed!
Kay Lancaster wrote:

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Other than for exercise, why bother? It's an annual. Ripping it out only loosens the soil, leaves a bare spot and sets you up for more weed seed germination. Keep the crabgrass mowed so it's not seeding, and it'll die on its own in the fall. Reseed and learn to mow properly and you'll have the problem licked.
Save the weed extractors for something they're truly useful for, like tap-rooted perennials. Unless you want the exercise.
Me, I'm a lazy gardener. But a good one.
Kay
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Thanks to all for your fine suggestions! I will take them all into consideration. I was thinking I needed to aerate the soil--it's very clayish. I bought a new lawn mower last month, so I know the blades are good. Before, I was using a mower with an old blade, but I had gotten it sharpened before using it on the newly grown lawn. I had mowed at the suggested height. I think I need to get the soil tested again.
<DIV><FONT face=Arial size=2><FONT size=2> <P>I'm in central Virginia, zone 7. I'm kind of new at the lawn thing. I planted my first lawn too late this past Spring, and it came in full and lush, but then got invaded by weeds and crabgrass, as I failed to put down preemergent. By now, half the lawn has turned into crabgrass and weeds. There is some grass, however, and I really don't want to retill and sew a new lawn. I'd really like to get rid of the crabgrass and overseed with fescue, but the crabgrass is still green and looks like it's reseeding itself. How should I approach this lawn if I don't want to retill the soil and resew a totally new lawn. I know fall is the prime time to plant grass and I was hoping I could overseed. Will I have to wipe out the crabgrass (which is pretty thick) by using a weedkiller? Is there still time to kill it, seed/overseed and hope for growth? I'd like to do all the proper fertilizing for new grass roots, so it would get nutrients during the winter and come back in the sping. Next spring.if I have grassI will definitely put down the preemergent!</P></FONT></FONT></DIV></BLOCKQUOTE></BODY></HTML>
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