Baking soda neutralizes the ph in the soil and nothing will grow there. use baking soda around all of the edges of flower beds to keep the grass and weeds from growing into beds. Just sprinkle it onto the soil so that it covers it lightly. Do this twice a year - spring and fall.
I'm gonna try this in a small flower bed - "Spray your weeds with diluted vinegar...not only will it kill them, but the plants and soil love it. Read how here, and see the before and after pictures. I just learned about this in my winter gardening class the other day and the teacher has done it for years."