What is a good homemade weed killer that will kills weeds but does not harm grass?

Answer

At this time to my knowledge there is no such thing as a weed killer that is selective enough not to kill grass. Your best bet is to find a weed killer and spray it directly on weeds while trying to avoid the grass, pulling out any weeds in your spare time will also help. Killing weeds before they seed is important to help keep their population down, but remember that some seeds will lie dormant in the soil for years and others will be introduced to your yard through wind or wildlife so you might not see a decrease in the population for some time.

Many household products will kill weeds safely such as vinegar, molasses, sugar, and boiling water. Vinegar is most effective when applied directly to the leaves of the plant.
Vinegar is often mixed with a dish soap or an essential oil (such as clove, or orange) to help it stick to the plant as well as add it's own effects. When using soap try to use something gentle and biodegradable and not anything antibacterial. Using vinegar on a hot day is often more effective because it helps to dry out the plant.
Molasses and sugar both stimulate microbes in the soil that will kill any plant that is there but this will leave the soil healthier than before so that grass can grow back. It can help to heat the sugar water or the molasses before pouring it on to kill the weed quicker.
Salt can also be used but high salt content in soil will prevent the grass from growing there as well. This is effective however for places you don't want anything to grow such as in between cracks in cement or in driveways.

Bleach should not be used to kill weeds since it will greatly raise the pH of the soil and prevent anything from living there including the grass. It also will harm any organisms that live in the soil such as earthworms and beneficial microbes.

Also, grass itself can become be an effective weed killer by crowding out the unwanted plants. Keep your grass healthy by aerating (many weeds prefer dense soil), leaving clippings and leaves on the yard to compost, adding a layer of compost over the entire yard in the fall (not too much to completely cover and kill the grass), and letting your grass grow to about 3 to 4 inches before cutting.

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if you're willing to give up on the homemade and organic bit you can buy selective weedkillers which will kill all broadleaf weeds and not harm your grass

First answer by ID0203617799. Last edit by Zaf. Contributor trust: 582 [recommend contributor]. Question popularity: 40 [recommend question]