# Spring Pre-Emergent or Overseed?



## greenthumb518 (Nov 4, 2021)

Morning all - I feel like I am overthinking this entire process. I can't decide if it would be better to apply pre-emergent in late winter and spring to focus on weeds....or go for an overseeding around April with a light mesotrione/tenacity app at seed-down. I did a renovation to my front and back yards this past fall 2021. I am seeing some good growth, but still have plenty of thin areas, some bare areas, and am starting to see a TON of Poa Annua. We have had a very warm fall and winter so far. My *ultimate goal* for this year is to have this grass thick and healthy enough to survive our hot hot hot summers with some help from my irrigation system.

Please help me figure out which way to go this Spring.

*Thanks in advance for your help*!

*Option 1*: Focus on weeds! 
---post-m in Feb (spot spray Tenacity+Triclopyr) and pre-m in March (granular Prodiamine)

*Option 2*: Focus on overseeding! 
---seed entire yard ~5lbs / 1k in late March or early April
---maybe put down a couple bags of Scotts Triple Action starter fert with Meso at time of seeding?

*Option 3*: Both!
---Spot spray Poa Annua and other weeds with Tenacity in Feb
---Spot seed thin and bare areas in late March
---maybe put down a couple bags of Scotts Triple Action starter fert with Meso at time of seeding?

***Desired seed to be used: Southern Belle TTTF & KBG mix from local Ace Hardware ***
https://www.horizononline.com/southern-belle/

*Here are some details about my lawn:*
-Location: Williamsburg, VA (transition zone 7b)
-Size: 4.2k sq ft (front) / 5.1k sq ft (back)
-Grass type: TTTF (front) [Rebel's Southern Mix]/ TTTF & KBG mix (back) [GCI Turf Cool Blue]
-Irrigation: In-ground sprinkler system covers 100% of the area; Need to do more testing to calculate its efficiency
-Front is north facing and full sun with minimal late afternoon shade from a large oak
-Back is south facing and partial sun with morning and mid afternoon shade from house and large trees

Soil test from 08/2021:


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## Old Hickory (Aug 19, 2019)

If you are going to use prodiamine then it needs to go out earlier maybe in a few weeks so it can get ahead of any germination. It lasts 4 months depending on the rate so it can go down early. But if you are going to seed then it needs to go down by mid-March, of course, depending upon your local weather forecast.

Is Tenacity effective with spot spraying poa? I don't know.


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## greenthumb518 (Nov 4, 2021)

If I throw down some prodiamine, then I would have to wait until Fall to do any overseeding, right?

I've heard mixed experiences with Tenacity on poa. I was figuring that even if it doesn't kill it, it should at least turn the poa white the help me find it and hand-pull it.

How's the Black Beauty Ultra? I was considering that seed blend too...still unsure between that or Southern Belle.


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## Powhatan (Dec 15, 2017)

Highly suggest fixing your low pH so more nutrients become plant available to support better grass growth. Also, include some soil amendments such as biochar to your lawn care applications so your low CEC (sandy soil) retain more moisture and nutrients.

If you seed early in the year and then irrigate to encourage growth, be prepared to combat fungal disease by using preventative/corrective fungicide treatments throughout the late spring through summer.

For our area, the fall preM (target winter weeds such as poa annua) should go down by early Sep, a split app works well to extend coverage period.

Don't know what is a good selective herbicide (if any) to control cool season weed poa annua in a cool season lawn. I normally hand-pull poa that I see and rely on the fall preM to minimize next year's poa appearance.


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## greenthumb518 (Nov 4, 2021)

Yessir roger that. I have started apply 80lbs of lime to the front and 80lbs to the back every 2-3 months since that August soil test. I am about to throw down my 3rd application.

I'm still pretty confused on timing of everything. Either overseed in Spring and do a split app Pre-M in the Fall.....or Pre-M in Spring and overseed in Fall? Can I Pre-M in the Fall as well? What do I do about my thin and bare areas right now/Spring?


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## Powhatan (Dec 15, 2017)

The grass will benefit with a higher pH to grow better/fuller, that will take some time.

I don't use Tenacity, so can't comment/recommend it's use to fit your program. The granular preM's I use, the labels typically say you can apply them after a certain period of time after seeding or after a certain number of mows. It's not ideal to apply preM late, but it's better than didn't apply at all.

Seeding a cool season lawn in the spring, especially in the transition zone, is not preferred, but it's a tool in the tool box, just be prepared for higher loss than if seeded in the recommended fall time. That being said, for my growing conditions with the zillons of trees that border the lawn, I normally late winter dormant overseed and get good results, and I don't irrigate cause I don't have adequate resources. The lawn is ~5 years old and is tremendously better now than when I first started. Sometimes I'll overseed in fall, but with the many leaves still on the trees along with the seasonal low sun angle, the new growth tends to have a harder time establishing. I've just learned to expect some losses along with the gains. As the saying goes, lawn care is a marathon, not a sprint.


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## LawnMavrik (Sep 22, 2020)

If spot spraying is an option, why not spot spray gly and reseed?


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## bigG (Jun 15, 2021)

@greenthumb518, I feel your pain. I'm in the transition zone too and your scenario sounds all too familiar. Tenacity/Meso does a piss poor job on Poa A, in both the pre and post emergent stages. It's also a rather crappy post emergent in general. Others have noted some small success with Tenacity on Poa A as a post emergent using it at the off label rates (low doses sprayed weekly/bi-weekly for "X" number of weeks). I tried that on a test plot last year and had very little success.

In general, Tenacity/Meso is mainly just good for some pre-m coverage at time of seeding and again ~30 days after germination to carry you to 60 days post emergent when you can apply a real pre-m like prodiamine. And keep in mind Tenacity/Meso will not prevent Poa A…as the label even states it will only "suppress" it, which is very different from prevent.

Spring seedings in the transition zone are tough and will see little success (again, been there, tried it). My advice, throw down a solid pre-m (prodiamine/dithopyr) this year and focus on post-emergent weed control using a 3-way product (such as Ortho weed-b-gon). Then, if you want to try an overseed in the fall, go for it and use the tenacity/Meso as recommended for seeding (at time of seeding and again 30 days after germination) but just know all that Poa A will come right back and then some. My personal plan this year is to skip the fall overseed and throw down a pre-m late summer/early fall to help knock back a ton of the Poa a.

Given you just did a reno this past fall, you'll be surprised how TTTF can "thicken up" a little and cover some bare spots…it doesn't spread like KBG but I say give it the spring and summer to grow and reassess this fall what game plan you want to go with.

Best of luck!


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## Old Hickory (Aug 19, 2019)

greenthumb518 said:


> How's the Black Beauty Ultra? I was considering that seed blend too...still unsure between that or Southern Belle.


Sorry for the delayed response. I installed sod a couple of years ago and the cool-season option was BBU so that's why I have it. So far? Other than some year one issues due to fungus and now a rigorous annual anti-fungus program...it's thick, beautiful, and lush. I only have but a few hours of direct sunlight, year-round, so I'm not sure if the lawn still has the original TTTF/KBG blend.


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## TurfMaster (Dec 12, 2018)

I like your option 3. I don't usually use pre-emergent except in my park strip since weed seed usually blow in onto the edge. I am going to be seeding as well. So for the pre-emergent this year I am going to try dythyopere (however you spell that), since it has some post emergent properties as well as pre-emergent properties and apply it when I see some turf starting to get to the point that I can get a couple of mows on it. I might also be selective on where I apply the pre-em. It's all an experiment.


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## Hiresdk (Nov 14, 2021)

I'll second those notes on Tenacity. It does NOT work to kill Poa. If Poa is a problem you have to go the Pre-M route in the fall and possibly again in the spring. You have to decide, like I did what is more important, 
1. Growing more grass seed 
-or-
2. Preventing new Poa to germinate.

Unfortunately that is what you are stuck with. You can't do both at the same time. I chose to overseed in spring and fall to try to boost my grass plants and then once I get that filled in I'll go for the Pre-M in the fall/spring to mitigate new poa germination.

You'll likely have a tough time with overseeding in spring because it is hard to keep those baby grass plants alive through the summer, but you can try. It's really a choice of what your desire more. . . more grass seed or limit weeds/new poa germination. You could try to putting more grass seed now if your priority is thicker grass and then do pre-M in the fall, but tenacity is not going to do much for you. I've tried and watched a million videos/articles. The grass factor Matt Martin just put out a video on a cocktail that was done at Purdue that seemed to have some results with killing Poa. You could look that up.

If you put any stock in Allyn Hane, he says if you have a POA problem and want to attack it to immediately stop any overseeding and go very agressive on Pre-M. But that assumes a relatively grown in lawn.


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## greenthumb518 (Nov 4, 2021)

Thanks everyone for the great information. Looks like I have a few decisions to make! Here is my modified plan:

-Skip the Tenacity spot spraying since it sounds like it will only be minimally effective
-Hand pull as much POA as I can and fill in the bare spots during my overseeding
-Overseed late winter/early Spring because I do have a fair amount of bare spots and thin spots.
-Once the overseed starts growing, wait at least 60 days and throw down some Prodiamine (lesco barricade) to help with the summer weeds.
-Monitor over summer, hand pull weeds, preventative fungicide apps, preventative pesticide apps, try to keep the baby grass happy 
-Spray trickier weeds with Triclopyr Ester (ortho weed b gon)
-Overseed late summer/very early Fall
-60 DAG - Throw down more Prodiamine to fend off the POA and other winter weeds
-Hibernate for the winter

Thoughts?


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## ceriano (Oct 6, 2021)

greenthumb518 said:


> Thanks everyone for the great information. Looks like I have a few decisions to make! Here is my modified plan:
> 
> -Skip the Tenacity spot spraying since it sounds like it will only be minimally effective
> -Hand pull as much POA as I can and fill in the bare spots during my overseeding
> ...


Per this discussion you need to go light on PERM.

https://thelawnforum.com/viewtopic.php?p=460049#p460049


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