Try Salt. Take a cheap spray bottle (Do not use an old cleaner spray bottle as it will be toxic to your pet), fill the bspray bottle about half full with salt and then pour in hot water until full. Shake the bottle until the salt has dissolved fully into the water, and then use the mixture to spray the unwanted weeds. The salt will dry the weeds up.
I've used 1 gal white vinegar + 1 cup regular table salt + 1 squirt of Liquid Joy dish detergent. I usually put vinegar and Joy in a watering can and in the sun for a bit. Add 1 cup salt and stir to dissolve. I just water grass, weeds, etc in the dog's pen and by the next day, they are all dead and withered. Hasn't affected any of my Shih Tzus, even those with badly compromised immune systems.
One of those hand-held torches works great at my house! Just torch what you want and poof! Weeds are gone.
For killing weeds & grass, Vinegar, put into a plant spray is one of the best there is! In fact, you can heat it up because the hotter it is, the better it works. For really tough areas, you can buy a much stronger vinegar at a plant nursery. This way, you can choose to add water or not, depending on the situation. Before giving up the idea of Vinegar. Try the SUPER-acidity kind they sell at plant nurseries. In fact, while you are at the nursery, ask them about other safe weed killers.
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