Posted: 07/07/2013 at 16:58
You can plant as soon as the weeds are cleared. Glyphosate doesn't persist in the soil. So as soon as the plant has died down, fork out any debris and you should have a clean bed for planting in. You need to spray on a still day as any drift of spray will kill any tree or grass it hits. If you accidentally get it on something you want to keep, wash it well with a hosepipe. If it rains within 24 hours you will need to repeat.
Paraquat and diquat will run through soil and can contaminate water courses. Sodium chlorate will persist in the soil for three years.
It might not be immediate, in that you may need a few weeks for it to kill something, but it is the least damaging to soil,and best for taprooted weeds.