how do you kill plants that keep coming up and wrecking my sidewalk?

Use a propane torch to burn out the weeds, sweep clean, then seal the cracks with a mortar based caulk to prevent new weeds from sprouting.

Use Roundup, it kills weeds to the roots and doesn't stay in the soil. You can use pathweeders, and they kill for a longer time but not as environmentally safe.

Rubber J had a good approach but you should also salt the cracks to keep any further germination from occurring, since the caulk will eventually loosen up.

a herbicide called Hyvar. it is a soil sterelant. nothing will grow where it contacts the soil. you can get it at your local farm supply store. sprays just like Roundup. watch out for runoff

My grandmother always had a good technique that never fails. It's environmentally friendly, but you have to be careful.

Take and boil one gallon of water and pour over the area. Be very careful not to splatter it on you, but it works every time!

u se boiling water and salt and pour an weeds.