# Replacement of crabgrass



## drfeno (Oct 2, 2018)

Hello,

last summer I disturbed a large area of my lawn while building a paver patio. The large area of bare dirt around it basically filled in with crabgrass. The crabgrass died last fall, so now there is a large area of dead crabgrass. In total its probably 1000 square feet or so. I've tried to research what to do, and it seems that I should put down a pre emergent chemical to prevent the crabgrass from re emerging. I'm told the seeds begin to germinate at soil temps of about 55 degrees F so I should put it down relatively soon (I live in northern CT). My question is, if I put a pre-emergent down, and it is effective in preventing crabgrass growth, will I be able to plant a desirable grass species on that same area during this growing season? If so, do I need to get rid of the old dead crabgrass "carcasses" before doing so?

Thanks,

Dave


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## Movingshrub (Jun 12, 2017)

Are you planning to seed grass or let existing grass expand into that area? I assume in Northern Connecticut you are likely to have a cool season grass vs warm season. Is there a reason you didn't seed in the fall after the crabgrass died? Are you looking to seed this spring or wait until the fall?


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## Ware (Jan 28, 2017)

@drfeno I'm moving this over to the cool season side due to your location.


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## Green (Dec 24, 2017)

drfeno said:


> I'm told the seeds begin to germinate at soil temps of about 55 degrees F so I should put it down relatively soon (I live in northern CT). My question is, if I put a pre-emergent down, and it is effective in preventing crabgrass growth, will I be able to plant a desirable grass species on that same area during this growing season?


If there is no good grass left in the area, and you decide you need to Spring seed, then no, you can't use traditional pre emergents. You will have to use Mesotrione and/or Siduron in this case so you don't kill your good seed. They only last 4-6 weeks per app, and have limits for how many times you can reapply.

We still have a few weeks of time left in CT for pre-Ms, and actually I haven't seen anyone put any down just yet. You can go by the Forsythia, which usually bloom at around 55F for timing.


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## drfeno (Oct 2, 2018)

Thanks All,

In the area I'm looking to fix, there is no desirable grass at all. I'm new to the science of lawn care so I didn't seed last year because I didn't know any better. I did buy a container of Prodiamine, to use for pre-emergent, but from what I'm reading here using that to prevent my crabgrass will prevent anything from growing there. Does Prodiamine have a time limit? I suppose I don't need to use it on my target area, I could just use it on the rest of my lawn which does need some weed control. I looked for the chemicals Mesotrione, and Siduron, but they are not easy to find at least in an internet search


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## g-man (Jun 15, 2017)

Prodiamine last months (depending on rate) and prevents the roots from new plants to develop.

Tenacity is the brand name for mesotrisone. It is the best product to use at seeding. It last 30days so it needs reapplication at 30days. After that you could do prodiamine.

You could buy tenacity in liquid and apply it using a calibrated sprayer. The other option is buying a granular starter fertilizer with mesotrisone. Scott's sells it and lesco on site one. It is a more expensive route, but works too.


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## g-man (Jun 15, 2017)

This is the domyown tenacity link.

One member is doing a split buy here.

I want to highlight that applying via sprayer is more challenging (no overlaps, consistent spray patterns)


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## social port (Jun 19, 2017)

Most of the big box stores that I frequent (e.g. Lowe's, Home Depot) carry the scott's Fert with mesotrione. The bag will typically say something like 'starter fertilizer' or 'food for new grass.' Just look for a label that reads: AI : mesotrione. The label is often on the bottom-right of the bag. Very small print.
If you are new to lawn care, this granular option from Scott's is an excellent choice, imo.


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## drfeno (Oct 2, 2018)

Thanks again for all the great advice. I actually did find that Tenacity was a product that contained mesotrione, and I did purchase a bottle of it. Since it lasts only about 30 days, my guess is that I should apply it to the target area when the soil temps get near 50-52F. I would then wait a couple weeks and then seed the area that I want to grow good grass in. I would also probably target the rest of my lawn for weed control. Also, we do have a garden in the summer, which is far away from the area of crabgrass that I'm trying to get rid of. But if I was going after weeds in areas closer to the garden, is there a distance I should stay away from it to be safe?


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## jessehurlburt (Oct 18, 2017)

drfeno said:


> Thanks again for all the great advice. I actually did find that Tenacity was a product that contained mesotrione, and I did purchase a bottle of it. Since it lasts only about 30 days, my guess is that I should apply it to the target area when the soil temps get near 50-52F. I would then wait a couple weeks and then seed the area that I want to grow good grass in. I would also probably target the rest of my lawn for weed control. Also, we do have a garden in the summer, which is far away from the area of crabgrass that I'm trying to get rid of. But if I was going after weeds in areas closer to the garden, is there a distance I should stay away from it to be safe?


You'd want to apply the Tenacity at the time of seeding. Not before. In 3 weeks when the seed has all germinated, you can apply prodiamine to cover you until the fall.


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## drfeno (Oct 2, 2018)

Thanks, I'm just learning all this. I thought it would be good to put it down a couple weeks before I seeded to allow it to do its pre-emergent thing, and then seed when it had lost a little of its effectiveness, put down the seeds that I want, even though its not supposed to hurt "good" seeds. So what you're saying is that even though tenacity is preventing the crabgrass from emerging, it will allow the "good" grass to grow since its selective in its targeting. So I would seed AND put down tenacity together before the soil temps reach 55F.


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## iowa jim (Jan 22, 2018)

jessehurlburt said:


> drfeno said:
> 
> 
> > Thanks again for all the great advice. I actually did find that Tenacity was a product that contained mesotrione, and I did purchase a bottle of it. Since it lasts only about 30 days, my guess is that I should apply it to the target area when the soil temps get near 50-52F. I would then wait a couple weeks and then seed the area that I want to grow good grass in. I would also probably target the rest of my lawn for weed control. Also, we do have a garden in the summer, which is far away from the area of crabgrass that I'm trying to get rid of. But if I was going after weeds in areas closer to the garden, is there a distance I should stay away from it to be safe?
> ...


I believe you have to wait 60 days after germination or after 2 mowings, whichever comes first to apply prodiamine to a newly seeded lawn.


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## Suburban Jungle Life (Mar 1, 2018)

drfeno said:


> Thanks, I'm just learning all this. I thought it would be good to put it down a couple weeks before I seeded to allow it to do its pre-emergent thing, and then seed when it had lost a little of its effectiveness, put down the seeds that I want, even though its not supposed to hurt "good" seeds. So what you're saying is that even though tenacity is preventing the crabgrass from emerging, it will allow the "good" grass to grow since its selective in its targeting. So I would seed AND put down tenacity together before the soil temps reach 55F.


I like to rough up the soil, seed, then drag the back of the rake over the seed to mix it with the top layer of soil. Seed does best when it has good contact with the soil and not laying on top of old leaves or old grass. Then spray the tenacity. Last, cover with peat moss and water.


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## drfeno (Oct 2, 2018)

Thanks again,

I'm also faced with all the dead crabgrass that still covers the area. Now I have planted grass successfully on other parts of the lawn, but its always been on basically bare dirt. I usually rake to loosen up the soil, spread seed and stater fertilizer, then lightly bury the seeds again with the rake. I have then usually covered it up with hay, and watered liberally. I would think in this instance it would be best to get rid of the old dead crabgrass first. This seems like it may be labor intensive, but I will probably do it. Or, could I spread seeds and fertilizer and tenacity then lightly put down some soil over it and let the dead crabgrass act as the hay?


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## Suburban Jungle Life (Mar 1, 2018)

drfeno said:


> Thanks again,
> 
> I'm also faced with all the dead crabgrass that still covers the area. Now I have planted grass successfully on other parts of the lawn, but its always been on basically bare dirt. I usually rake to loosen up the soil, spread seed and stater fertilizer, then lightly bury the seeds again with the rake. I have then usually covered it up with hay, and watered liberally. I would think in this instance it would be best to get rid of the old dead crabgrass first. This seems like it may be labor intensive, but I will probably do it. Or, could I spread seeds and fertilizer and tenacity then lightly put down some soil over it and let the dead crabgrass act as the hay?


The seed should touch the soil so maybe mow it really low and bag it or mulch it. Then if you have a dethatcher or verticutter, that would be great. In lieu of that, a solid raking to loosen the top layer of dirt would be a good idea.


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## jessehurlburt (Oct 18, 2017)

iowa jim said:


> jessehurlburt said:
> 
> 
> > drfeno said:
> ...


Matt Martin said you're good to apply as soon as root is tacked down. I like to be cautious and wait 3 weeks. 60 days or 2 mowings? I mow twice a week in the spring- I'd probably be at 15 mows by 60 days.


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## iowa jim (Jan 22, 2018)

I just checked the prodiamine label and it says 60 days or 2 mowings. If Matt says its okay it is probably okay as he is the grass guru as far as i am concerned. I just don't want to see anybody hurt there new grass.


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## drfeno (Oct 2, 2018)

Since I now have both Tenacity and Prodiamine, and I plan to use the tenacity when I seed the area I'm looking to fix, Could I just wait a month or so after the new grass takes, and then apply Tenacity again to try an further control the weeds. I have no issue not using prodiamine at all this season. I could wait and use it next spring if all goes well this year.


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## jessehurlburt (Oct 18, 2017)

drfeno said:


> Since I now have both Tenacity and Prodiamine, and I plan to use the tenacity when I seed the area I'm looking to fix, Could I just wait a month or so after the new grass takes, and then apply Tenacity again to try an further control the weeds. I have no issue not using prodiamine at all this season. I could wait and use it next spring if all goes well this year.


I am wondering the best approach for this question as well. There are limits on how much Tenacity you can apply in a year, and it only last about a month, so I would imagine the best bet would be to seed with Tenacity, do a follow up app one month later, then after 2-3 mows drop prodiamine to get you by until fall. I'd be curious to hear more experienced members opinions however.


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## Chris LI (Oct 26, 2018)

@jessehurlburt 
I haven't done this, but it sounds like a good plan to me. You should make the 60 day rule for Prodiamine. However, if your'e looking to seed again in the fall (late summer), you may need to perform an aggressive dethatching/aeration for the fall season prep in order to break the barrier, due to the long residual. It may be worth it to pick up some Dimension to drop in the spring instead, if you're looking to seed in the fall. Then you can do the Tenacity/Prodiamine combo. Someone with a little more experience should jump in and comment.


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## jessehurlburt (Oct 18, 2017)

Chris LI said:


> @jessehurlburt
> I haven't done this, but it sounds like a good plan to me. You should make the 60 day rule for Prodiamine. However, if your'e looking to seed again in the fall (late summer), you may need to perform an aggressive dethatching/aeration for the fall season prep in order to break the barrier, due to the long residual. It may be worth it to pick up some Dimension to drop in the spring instead, if you're looking to seed in the fall. Then you can do the Tenacity/Prodiamine combo. Someone with a little more experience should jump in and comment.


The residual on Prodiamine is determined by how much you put down, I believe. If went with .5lbs/a I believe that would give me 3 months of coverage. I'm going to start my 2019 thread soon and will be certain to confirm first.


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## drfeno (Oct 2, 2018)

Here's what I did, we'll see what pops up:

the area I need to replace is about 1000 square feet. I removed the old dead crabgrass as best I could, and roughed up the soil. I put down Tenacity doing it as evenly as I could. The directions called for 5-8 ounces per acre, and I'm dealing with about 1/43 of an acre, which works out to be about 1 teaspoon of chemical. I mixed it with 2 gallons of water, and put the entire amount down trying to get it even. I then spread the seeds in basically the correct density it called for on new lawns. I put down some starter fertilizer, and lightly raked to bury the seeds. Covered the entire area with a thin coating of straw, and watered. I will continue to water each day, rain dependent. We'll see.

Thanks for all the advice.


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