How long does Round Up type killer last?

[noob]

I was reading on re sodding the lawn, and they treated it with the round up that kills all plants, and covered it to bake what's left. Then waited 3 weeks before ripping it up and putting new sod

 

[dantheman]

It's black looks like tarp almost but has a cloth feel. Walmart, Home Depot and Sam's carry it with Sam's Club having the best price I found. You put it down and stake in it blocks all sun so the grass will eventually die from being covered and just cut holes where you want to plant you can then cover it with mulch or mix in some soil of your choosing before putting the preen down.

Preen is a granular herbicide . http://www.preen.com/

 

[CEHollier]

Preen is a granular herbicide . http://www.preen.com/

Dan I believe Preen is a pre-emergent. Spectacle and Snap Shot are two other pre-emergents.

 

[Leonidas]

I have a rondup question too. What if I spray a portion of my yard to kill the grass, how long do I have to wait until planting a garden?

Just cover the area with cardboard or newspaper. It'll be dead in a week or so. No chemicals, and the soil will pick up some nutrients from the "mulch."