[Green]

Let's say you have a hardscape where you need to use glyphosate, and it's at the top of a slope.

If you spray, then the next time it rains, what's the chance of the glyphosate washing down into the lawn below with the rain, and causing damage to the grass?

 

[Greendoc]

Minimal. The rain dilutes the Glyphosate to the point of it no longer affecting most vegetation. However, that can change if there is more than just Glyphosate in the sprayer. On pavers, and gravel mulched areas, I prefer propane. No need for the gloves and boots. I just keep a water hose nearby.

 

[JohnP]

The crack weed burn is the best kinda way to deal with them. Plus then your neighbors think you're crazy and leave you alone

 

[Greendoc]

I use the huge torch attached to the 20 lb tank. Actually the neighbors love me because I am not spraying.

 

[Delmarva Keith]

Gly is a strong chelating agent. It was originally "discovered" for that purpose and then somebody noticed it killed plants too. Even soil dust on plant leaves fixates with gly and reduces its effectiveness. Gly, properly applied, has no soil activity. It will only affect the plants it is sprayed on. It is just about the perfect systemic for weed control on hardscapes and in landscape beds.

One big caution is they sell "long acting" or "Max" or "365" gly which includes imazapic or imazapyr. Both are active in soil, will wash off the hardscape and will likely adversely affect nearby plants and even nearby trees up to 2x the canopy dripline. Don't get that kind.