I’ve said this before, but it bears repeating: Whenever you’re shopping for dishwashing liquid to use in your yard or garden, make sure you choose a brand that’s made with pure, mild soap. Avoid any product that contains detergents or degreasing agents. They can harm your grass (or any other plants that they touch). And whatever you do, avoid all products that boast their antibacterial prowess. Not only will they damage your greenery, but they’ll also kill off good bacteria along with the bad – and that can cause big trouble.
There is one exception to this rule, and that is when the soapy solution will not come in contact with valuable plants. If you’re aiming to destroy weeds, clean inanimate objects, or kill pests that you’ve removed from your plants, feel free to use any kind of soap or detergent you have on hand – and make the “medicine” as strong as you like.