I went back to check on a block paving cleaning job yesterday as I always do when I'm working in the same area and noticed in one corner near the entrance to the drive there was a small area of grassy weeds (in a joint about 10cm long and is about 3cm tall already). The rest of the drive is fine, but its just the one area. I cleaned it about 6 weeks ago. I always explain to customers about not being able to fully prevent weeds etc and the odd weed afterwards is to be expected. The customer has not rang me to complain, i just checked back on the job. This is the only job it has happened on this season.
My normal procedure on paving is glyphosate/clean/re sand/residual which I did on this job. I'm just trying to work out why this has happened so I'm just after a second opinion and to bounce thoughts around as this is driving my ocd crazy.
Thing is I don't remember there being any grass in the area before pre treating the paving and if it was then I'm 99% sure I would have sprayed it as I'm very particular, or maybe it didn't receive enough glyphosate.
Could it have been a seedling that was in the joint already and perhaps I didn't clean that particular joint out thoroughly to wash it out.
Maybe I didn't lay the residual on thick enough and the seed settled without a battle.
Thanks for any help, it'll be good to hear feedback as this is driving me nuts.