If you need a handy way to kill weeds, especially those that grow in sidewalk or driveway cracks, pour white vinegar in a pressurised spray bottle and liberally coat any area with weeds. The acetic acid in vinegar will kill most types of plant life within 24 hours, so don’t spray any plants you want to keep alive.
Gardening weblog Gardening Rhythms recommends filling your spray bottle to two-thirds of its capacity and claims that vinegar is more effective than chemical sprays as it will kill the weeds overnight while some herbicides can take up to a week.
Three Simple Quick Tips for Controlling Garden Pests – Video [Gardening Rhythms]
Tim
Sunday, December 18, 2011 at 6:23 PMIf you want to keep the weeds out sweet salt between the cracks then water it in. Kills the plants within about 48 hours and stops new weeds from growing for a good four months or so.
Big bags of pool salt are about 6 bucks from Bunnings and will last forever.
Martin
Sunday, December 18, 2011 at 8:55 PMyou also need lemon juice, as this helps to break down the surface of the weeds to allow the vinegar to do its work better (this is what I have been told, I dont have any references to back this up either).
If you want a stupid fast way to kill weeds off in a day, poor boiling water over the weed, dead within 2 days.
olearymo
Monday, December 19, 2011 at 9:12 AMAcetic acid is also useful as a weapon against Raxacoricofallapatorians
Spanky
Monday, December 19, 2011 at 11:39 AMI found (by accident) that a quick hit with WD40 will kill them off and they won’t grow back, got some on my lawn some 18 months back and the patch still hasn’t grown back. Rest of the lawn has been perfect!
olearymo
Tuesday, December 20, 2011 at 10:14 AMThe only true solution: Flame. Thrower.
http://www.flameengineering.com/Weed_Dragon.html