# Pre Emergent Soil Temp Window



## Stellar P (Apr 13, 2018)

What is the soil temperature range to apply a Spring pre emergent?

It's my understanding that seed germination is around 70 degrees (+/- depending on species), so a good window to apply is around the 60-65 degree range. If I put pre em down too early, I'm afraid the pre em will be less effective at the germination range from increased heavy rains that come with the area warming up.


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## SCGrassMan (Dec 17, 2017)

Put it down now through 2 weeks from now is my non-expert opinion. Hit it 3x a year instead of 2x if you're concerned.


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## LowCountryCharleston (Jun 21, 2018)

I"m doing mine this weekend. Temps are starting to creep up


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## cglarsen (Dec 28, 2018)

I just ordered mine from pestrong so will be laying down a split blanket app soon and repeat about March 1.


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## BakerGreenLawnMaker (Mar 13, 2018)

I'll be applying some in two-three wks from now.


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## JWAY (Oct 16, 2018)

My lawns already right at 55 degrees and 60 in a few places which is around the temp that Crabgrass is said to germinate.
Going to apply Prodiamine this weekend since I had a lot of Crabgrass last summer.

If it keeps raining like it has been, may need to apply some Simazine (instead of anther app of Prodiamine) in early spring to keep from going over the annual max of Prodiamine that I plan to use for fall app.

https://schoolipm.tamu.edu/2016/02/19/crabgrass-germination-advice-for-homeowners/


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## Mightyquinn (Jan 31, 2017)

I usually wait until I am done scalping and verticutting as doing those two things alone will remove a lot of the weeds you may have. If I do see quite a few weeds, I will mix in some Celsius with my Prodiamine when I spray it. Kill two birds with one stone


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## Stellar P (Apr 13, 2018)

JWAY said:


> My lawns already right at 55 degrees and 60 in a few places which is around the temp that Crabgrass is said to germinate.
> Going to apply Prodiamine this weekend since I had a lot of Crabgrass last summer.
> 
> If it keeps raining like it has been, may need to apply some Simazine (instead of anther app of Prodiamine) in early spring to keep from going over the annual max of Prodiamine that I plan to use for fall app.
> ...


I don't know were I picked up the 70 degree mark for seed germination, but that's what I was understanding. Looks like I need to apply ASAP. If it doesn't rain this Saturday, I'll apply 0.3 oz Prodiamine. Then 0.1 oz after the hard rains have gone away. Way to start 2019 on the right foot ya jacka$$!


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## adgattoni (Oct 3, 2017)

Mightyquinn said:


> I usually wait until I am done scalping and verticutting as doing those two things alone will remove a lot of the weeds you may have. If I do see quite a few weeds, I will mix in some Celsius with my Prodiamine when I spray it. Kill two birds with one stone


Do you find the verticutting breaks your pre-em barrier? This will be my first season with a verticutter, and I'm contemplating using more frequent applications. Normally I just do a 6 month rate.


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## Mightyquinn (Jan 31, 2017)

adgattoni said:


> Mightyquinn said:
> 
> 
> > I usually wait until I am done scalping and verticutting as doing those two things alone will remove a lot of the weeds you may have. If I do see quite a few weeds, I will mix in some Celsius with my Prodiamine when I spray it. Kill two birds with one stone
> ...


I apply the preM after I verticut so as not to affect the efficacy of it.


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## LowCountryCharleston (Jun 21, 2018)

Stellar P said:


> JWAY said:
> 
> 
> > My lawns already right at 55 degrees and 60 in a few places which is around the temp that Crabgrass is said to germinate.
> ...


Hey Stellar P 
This link is great to see going back 5, 10 years what the avg dates are for temps 55, 60, 65 etc to then plan accordingly. 
http://www.greencastonline.com/tools/soil-temperature

I'm putting mine down this weekend as the soil temps are close to 50 degrees and we have a warm up coming all next week in the mid 60's and 70's.


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## Stellar P (Apr 13, 2018)

LowCountryCharleston said:


> Hey Stellar P
> This link is great to see going back 5, 10 years what the avg dates are for temps 55, 60, 65 etc to then plan accordingly.
> http://www.greencastonline.com/tools/soil-temperature
> 
> I'm putting mine down this weekend as the soil temps are close to 50 degrees and we have a warm up coming all next week in the mid 60's and 70's.


Yeah. That's the site I use. I just got my wires crossed for some reason and thought my app should be between 60-70 degree soil temps.


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## CenlaLowell (Apr 21, 2017)

I think I may miss my window. Here is my 8 day window.


Now my question, are my fall pre emergents working? I applied prodiamine 9/5/18, diythpor 9/18/18, and princep 10/20/18. I will not be able to apply anything to the lawn until Monday or Tuesday next week.


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## BakerGreenLawnMaker (Mar 13, 2018)




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## LowCountryCharleston (Jun 21, 2018)

Charleston,SC- it's supposed to rain a bit down here this morning and it's gonna warm up to mid 70's all week can I thrown down my Prodiamine after the rain stops? I figure Yes since I'm spraying but just wanna double check. 
Thanks!


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## SCGrassMan (Dec 17, 2017)

LowCountryCharleston said:


> Charleston,SC- it's supposed to rain a bit down here this morning and it's gonna warm up to mid 70's all week can I thrown down my Prodiamine after the rain stops? I figure Yes since I'm spraying but just wanna double check.
> Thanks!


Being that it needs a half inch of water why not put it down before the rain?


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## LowCountryCharleston (Jun 21, 2018)

Ah yeah good plan. Thanks!

Welp, it's now raining out. Can I still apply when it ends and the ground is good and wet?


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## SCGrassMan (Dec 17, 2017)

LowCountryCharleston said:


> Ah yeah good plan. Thanks!
> 
> Welp, it's now raining out. Can I still apply when it ends and the ground is good and wet?


Absolutely, or during!


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## Ortho-Doc (Feb 3, 2019)

Crazy heat wave hitting the south this week. Does this every year here. The temps spike, all the flowers start budding up, then a bone chilling freeze hits and ruins the local peaches for the year. The spring freeze date in my area is March 27th. Does a one week heat wave and a few days of soil temps above 55 determine pre-emergent timing or do I need to look for a week or two of temps above 55?


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## CenlaLowell (Apr 21, 2017)

What's crazy here it's supposed to be in the 70s then Saturday there a low of 33. Weather is insane &#128552;


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## Easyluck (Feb 5, 2019)

Ortho-Doc said:


> Crazy heat wave hitting the south this week. Does this every year here. The temps spike, all the flowers start budding up, then a bone chilling freeze hits and ruins the local peaches for the year. The spring freeze date in my area is March 27th. Does a one week heat wave and a few days of soil temps above 55 determine pre-emergent timing or do I need to look for a week or two of temps above 55?


So I'm new to the forums but I have the same question.

Last week the polar vortex brought freezing cold temperatures and my soil temperatures dropped to 42-45 degrees. This week we have had a warm spell and when I checked my soil temperatures today I was surprised to see 55 degrees!

I put a half application of prodimine down in late September 2018. We have had a ton of rain this winter so I'm not sure how effective the prodiamine still is after 4 months.

If crabgrass starts to germinate and then we get another polar vortex type of event, will that kill the germinated crabgrass?

Second question. I could go ahead and spray a split application of prodiamine but 6 months from now would be the first of August. Would it be ok to spray prodiamine in early August? How would you adjust your pre emergent program to these conditions?

I also have dimension. Would it be better to spray that now and spray prodiamine in late March or April?


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## dfw_pilot (Jan 28, 2017)

@Easyluck, Welcome to TLF!

As long as you keep your barrier down year round, the actual dates don't matter too much. However I do like to have the most potency during the spring warm up. If you use prodiamine, put half the annual max rate down in late Feb/early March, and then the second half six months later. There are lots of opinions and ways to do it, however.


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## Sidney (Jun 12, 2017)

So I want to piggy back on Ortho_doc comment. I'm here in Columbia, SC and it is in the 70's and even 80's this week. I'm sure we will be back to freezing next week. Will the weeds start to germinate then die off if a freeze comes through? I was going put down liquid prodiamine this week whenever it arrives. Will it be too late?


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