# Pre-Emergent when soil temp is 55*F????



## MsTin (Sep 5, 2017)

Alright so I live south of the DFW area and I see that some of you guys are already putting down your pre-emergent's for the fall/winter. I read here http://www.domyownpestcontrol.com/lawn-care-schedule-for-warm-season-grasses-a-538.html



that you want to put it down just before the soil temp reaches 55 degrees F. Should I wait and monitor my soil temperature or just go ahead and put it down? This will be the first time that I am putting pre-emergent down on my front and back lawn since having Bermuda sod laid this summer.


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## Mightyquinn (Jan 31, 2017)

If you do not have a PreM barrier down, then there is no time like the present to start one . Just know how much you are putting down so you know when to reapply it to keep the barrier intact.


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## Movingshrub (Jun 12, 2017)

http://www.greencastonline.com/tools/soil-temperature

One, of many, resources to measure soil temp.


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## Bunnysarefat (May 4, 2017)

I laid down my pre e 2-3 weeks ago and I've already seen Poa annua that must have germinated just before I put it down. It showed up in some very cool areas (corners) of my yard. There's no way any full sun soil is 55 degrees.

I'd say play it by ear based on your own yard. I'm in Grapevine, as you know we got a bit of a cooler break at the beginning of September. Not crazy but definitely noticeable. For my own yard, I know the Poa annua and rescuegrass threat is extreme so I wasn't about to take any chances and laid it early before forecasted rain at the end of August. If you are confident the seeds aren't there then you could push it later, but you might as well do it now, no rain in the forecast. You could even just plug a thermometer in the ground.


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## Mightyquinn (Jan 31, 2017)

If you want to check your own soil temperature you can get a cheap digital meat thermometer at Walmart and use it to check your soil temps.


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## Bunnysarefat (May 4, 2017)

Oh, just realized who the original poster was. This is a new house so you don't know.. duh.


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## Ware (Jan 28, 2017)

I apply Prodiamine at the 6mo rate, so I don't worry much about actual soil temps - I just shoot for mid-September, ahead of some rain in the forecast. Being a few weeks early with a product that works for ~6 months doesn't concern me. :thumbup:


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## ATLawn (May 25, 2017)

My guess is that site is talking about your spring Pre-em application, not fall.


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## MsTin (Sep 5, 2017)

So I stopped by SiteOne and the guy there gave me a pre-emergent with the fertilizer that I purchased there. So I ended up putting some down. You all are so awesome on this thread and so generous with your advice. Thank you all soooo very much! That website to check soil temps is awesome!


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## Movingshrub (Jun 12, 2017)

ATLawn said:


> My guess is that site is talking about your spring Pre-em application, not fall.


I'd be inclined to agree. Crabgrass germinates around a soil temp of 55F, where as for annual bluegrass it's when soil temp drops below 70F?


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## Ware (Jan 28, 2017)

MsTin said:


> So I stopped by SiteOne and the guy there gave me a pre-emergent...


What was the pre-e active ingredient?


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## MsTin (Sep 5, 2017)

Ware said:


> MsTin said:
> 
> 
> > So I stopped by SiteOne and the guy there gave me a pre-emergent...
> ...


Pendimethalin, N-( 1-ethylpropy)-3, 4-dimenthyl-2, 6-dinitrobenzenamine......0.86%


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## MsTin (Sep 5, 2017)

Movingshrub said:


> ATLawn said:
> 
> 
> > My guess is that site is talking about your spring Pre-em application, not fall.
> ...


This is good to know!


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## dfw_pilot (Jan 28, 2017)

A great option for pre-m is Dimension®. It's granular, easy to spread in a fertilizer spreader, is sold at SiteOne, and will last longer and work better than Pendimethalin.

I agree that while monitoring soil temps is a good habit (I do), the better method is to simply keep the weed barrier down year round - for no fuss.


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## Movingshrub (Jun 12, 2017)

dfw_pilot said:


> A great option for pre-m is Dimension®. It's granular, easy to spread in a fertilizer spreader, is sold at SiteOne, and will last longer and work better than Pendimethalin.
> 
> I agree that while monitoring soil temps is a good habit (I do), the better method is to simply keep the weed barrier down year round - for no fuss.


You can also use a generic. The chemical name is dithiopyr.


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## dfw_pilot (Jan 28, 2017)

Movingshrub said:


> You can also use a generic.


 :thumbup:


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## MsTin (Sep 5, 2017)

Could I just shoot my laser thermometer to the ground and get it that way or take my soil plugger that can take 6" plugs and shoot the laser into the hole? Would that work as well?


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## J_nick (Jan 28, 2017)

MsTin said:


> Could I just shoot my laser thermometer to the ground and get it that way or take my soil plugger that can take 6" plugs and shoot the laser into the hole? Would that work as well?


The very top of the soil will vary greatly if the sun is beating down on it. I was messing around with a FLIR camera earlier this year and from full sun to recently shaded areas were measuring 20 degrees difference. I think your second method could work.

A third option that I know a lot of us use is a meat thermometer.


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