How long after I use weed killer do I have to wait till I mow?

Question

The weeds are taller than the grass and will get mowed. Has the weed killer soaked into the roots, after say 24 hours, to mow, or do I have to wait till the weed killer starts working (visibly)?

Also wondered: how does week killer know not to kill grass?

Answer 1

24 hours is long enough. it helps if you give the weeds one last drink!

Answer 2

Barney,
You can mow the second day after you've applied the weedkiller; it's gotten down to their stubborn little roots by this time. It may be a couple of weeks before you notice the weeds dying, however, so don't be discouraged.
Broadleaf weeds and grasses are two different types of plants, and respond differenetly to what's applied to them. Obviously, products like Weed-B-Gone don't contain any ingredients to harm grass. There are products that do the direct opposite, too. Grass-B-Gone can be applied to grass infestations in a flower bed, killing the grass, but doing no harm to your flowers!
>^..^<

Answer 3

Most times it tells on the container. My say do not mow or water for 24 hours etc.
I use Roundup and usually mow the next day. But, I have weedwacked and sprayed an area and then covered with mulch and nothing comes up, though the mulch itself may do this. (This like in a 1-2 hour period of start to finish).

Answer 4

Because you are a male, I assume the idea of reading the instructions on the weed killer label, didn't cross your mind. If you do read it, I'm sure it will give you all the necessary information for best practise of their product.