Exisiting grass too tall for new grass?

adscl84September 17, 2013

Immediately prior to slit seeding my yard (appx. 1 week ago), I cut the existing lawn to about 1.5". Something tells me I should have gone shorter, but I was afraid of going too short, as I've been mowing at 3" all year and the grass was probably about 3.5-4" when I cut it.

I can already see some sprouts (very few) growing where there is no grass around, but the existing lawn is growing fast and I'm afraid it might prevent the new seed from growing.

Could I cut the existing grass down again -- before a lot of sprouts come up -- without doing much damage? Or am I be better off leaving it alone?

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I'm not one of the experts on here but I would think the mower would blow your seeds and it would be counterproductive to establishing good soil contact. If I were you, I'd wait until your new grass is rooted.

    Bookmark   September 19, 2013 at 3:08PM
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dchall_san_antonio(8 San Antonio)

I agree, leave it alone. There is a trade-off when overseeding into an existing lawn. Some sprout and you lose some. Mow when the new grass is 3 inches high.

    Bookmark   September 20, 2013 at 12:52PM
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In the larger bare spots (appx. 4 sq. ft.) some of the new grass is just under 2" tall, some of it has just started poking up through the dirt, and some of it is inbetween.

Which of these should be 3" tall when I mow? I can't really tell how tall the stuff within the existing lawn is. The existing lawn is at least 5" tall now.

    Bookmark   September 23, 2013 at 2:02AM
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dchall_san_antonio(8 San Antonio)

Mow the tall grass and avoid the areas where the new grass predominates. When it gets to 3 inches, mow it back to 2. The tightrope you are walking is to avoid breaking the new grass (under 1 inch) and still allow enough sunlight down into the new grass so it will take root.

    Bookmark   September 23, 2013 at 9:59AM
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Thanks for the help. I mowed to just under 4" and maybe the grass wasn't quite as tall as I thought in most spots. Sometimes I felt like nothing was getting cut, but some of it was easily 6"+. The grass felt super plush when I walked on it, so I'm hoping I didn't do too much damage because I would love to keep it like that.

I've watered lightly twice a day for the last two weeks and decided to back off to a slightly heavier watering once a day now that it looks like most of the grass that sprouted is at least 1". When should I stop doing that and start the "deep and infrequent" watering again? After the first mowing of the new stuff?

    Bookmark   September 24, 2013 at 11:36AM
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