Weed and grass killer tip... vinegar. A neighbor noticed some grass was working it's way between my pavers and said that pouring or spraying with plain old vinegar would kill them as it's an acid. Very inexpensive too, $2 a gallon.
So I tried it. I saw no difference the next day but on day 3 they were all dead, Bermuda grass, chickweed and some other stray grasses. All gone and no scary chemicals.
I tried this on my gravel driveway......full strength white vinegar and a drop of dish detergent in a spray bottle, in hot full sun. Tops turned brown, roots came rightt back up nice & green. Lot of work for nothing, it's a large driveway.
I am highly allergic to commercial weedkiller, so I now use gasoline. (Which i have on hand for the mower). I am not allergic to it & it works great, just put in a spray bottle....of course i never smoked.....
If this works I will be deeply in your debt. I have a paver driveway that is more than a 1,000 sq ft, and have spent multiple days weeding it with a knife in the past. I will definitely be trying this.
Do you expect to need to reapply yearly? I should imagine yes. Did you notice if it stained the pavers? Did you you just apply it to the plants you could see or did you try to hit all the seams?
Just the clear white vinegar we use to clean our hardwood floors I think.
I use 40% vinegar with citric acid added. Spray it on early on a sunny day. Poison Ivy will back down from it. Regular vinegar may control some grasses, but poured into the soil will kill all the beneficial insects and around 90 % of the good microbes.