Baking soda and weeds ... Baking Soda Looking for a safe way to keep weeds and grasses from growing in the cracks of your paved patios, driveways, and walkways? Sprinkle handfuls of baking soda onto the concrete and simply sweep it into the cracks. The added sodium will make it much less hospitable to dandelions and their friends. Try it 2x/yr, spring and fall. Site has other ways to kill weeds.
Natural Weed Killers - 11 Ways to Kill Weeds Without Poison
Homemade Weed Killer 1 gallon of white vinegar, 1/2 cup salt, Liquid dish soap (any brand), Empty spray bottle. Put salt in the empty spray bottle and fill it the rest of the way up with white vinegar. Add a squirt of liquid dish soap. This solution works best if you use it on a hot day. Spray it on the weeds in the morning, and as it heats up it will do its work.