I have found boiling water or bleach very effective too when poured/sprayed on weeds only, avoiding surrounding plants.

I have tried all the home-made remedies, including the one above, without success.  The one suggested will only desiccate or dry out the leaves.  It doesn't kill the plant's root, so the weed can, and frequently does, grow again.  Boiling water will kill weeds and their roots.  If you have a lightweight steam cleaner and enough electric leads, this works a treat. Living on acreage, this doesn't work for me.   I have found the best 'eco friendly' weed killer that actually works is a product called Slasher from Bunnings.  Also there is a physical weed remover that you can buy which is easy to use and works brilliantly from a standing position, so no bending.

Petrol is also highly effective ! a piece of cloth tied to a stick, soak in petrol, and dab onto the weed. Not when it is going to rain.