Pull out by hand single weeds or grasses. Lift them out of the soil slowly to ensure that the entire root is extracted. This is essential to prevent the unwanted vegetation from returning.
Pour baking soda onto any weeds or grasses that are growing through the seams of concrete. Sweep any excess baking into the cracks with a broom. This will make the soil unsuitable for plant growth, so don't apply baking soda close to desired plants.
Bring a solution of 1 part salt and 2 parts water to a boil. Pour the solution directly on weed or grass clusters you wish to kill. Repeat as necessary to kill any re-sprouting vegetation.
Pour undiluted white vinegar into a spray bottle and spritz weeds and grasses with it. The high level of acidity will be toxic to the weed. Repeat as necessary.