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grass seed before weed preventer

Use the down arrows in that window to “scroll” through all the instances where that word appears. As I did this, I found the following very quickly.

The formulation most of you have is the “DF” which stands for “dry flowable” which means it’s small granules that you put in water to make a solution to spray. The concentration is 75% quinclorac.


This is another weed control I have recommended heavily and they list right on the label in clear printing how long to wait until you seed. Keep in mind, this product has an 85F degree temp restriction anyway so many of you would not be using it in summer, but in case you did, here is the wait time after app before seeding:

Here is what it looks like up close:

So in our case, where we are thinking about seeding the lawn, if we are planning to seed Bahia grass for example, then this product is out, 100%. No Bueno.

Treating the whole lawn is the smart approach for ultimate control, since you can expect that the crab grass seeds are widely dispersed everywhere. They will try to pop up anywhere they can, leaving you with the need to repeat this process time after time. 

There are a few variables that could affect the actual down time. How heavily the pre emergent is applied, how much irrigation it undergoes, and whether or not the soil surface is disturbed, all can lessen or increase the duration of its effectiveness. 

Sta-Green Crab Grass Preventer specifies that the product can be effective up to 4 months, and recommends that you wait at least 12 weeks after application before reseeding. 

QUESTION 2: Already Applied
Pre Emergent.  Can I Reseed?

I applied to my lawn the Crab Grass Preventer by Vigoro.
How long do I need to wait before I can sow some new grass seed on the lawn? I was planning on using a slit seeder to apply the grass seed.

Yes, you can argue that it is better to be safe than sorry, and you may not want to let a single weed get a chance to live.
Yes, I have seen it happen that the seams where the sod pieces butt together is the likely place where any crabgrass sprouts might pop through. 

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To clarify, do NOT reseed until you are certain that the weed preventer is no longer active.