Boiling hot water can destroy growing weeds very quickly (and easily). Top tip: take care when pouring the boiling water not to damage any nearby flowers or plants, so only pour small, controlled amounts to avoid the water splashing.
The most effective homemade option is a mixture of white vinegar, salt, and liquid dish soap. Each of these ingredients has special properties that combine to kill weeds. Both the salt and the vinegar contain acetic acid, which serves to dry out and kill the plants.
Using Bleach to Kill Weeds Permanently
Apply one cup of bleach, undiluted, to the afflicted area. Wait until the weeds turn brown before pulling them out of the ground. Run water around the area to flush the bleach, especially if you are trying to grow plants or grass in that area.
Vinegar is acidic and will eventually kill most broadleaf weeds, but the acid will kill the leaves before reaching the root system, and the weeds may grow back quickly.
Table Salt - Using salt to kill weeds is a common do-it-yourself solution. When salt is absorbed by plant root systems, it disrupts the water balance and causes the weed to eventually wilt and die. But salt by itself doesn't make a very effective weed killer.
Pouring boiling water on weeds can be used especially in situations where other plants are not nearby, such as in cracks in patios or sidewalks. Boiling water will act as a contact "herbicide", killing only the portion of the plant it comes in contact with. It is most effective on young, newly emerged weeds.
The best way to kill the existing lawn and weeds is to apply a nonselective herbicide, such as glyphosate, over the entire area. Glyphosate is a postemergence translocated herbicide that effectively kills turf and grassy and broadleaf weeds. Glyphosate is translocated rapidly in all actively growing plants.
White Vinegar:
For it to work, you have to wait for the vinegar to sit in the weeds from your garden for a few days. The vinegar will kill the weed's roots.
Baking soda makes an incredible weed killer especially when it is mixed with other kitchen staples, like vinegar or lemon juice. Just dissolve 1 ½ cup of baking soda and a tablespoon or two of vinegar in a gallon of water. Transfer the concoction in a spray bottle and spritz away!
A non-selective weed killer, such as Roundup, is a great option for killing weeds and grass permanently. The Glyphosate in Roundup works by infiltrating the plant through the leaves. From there, it attacks all plant systems and kills them completely, including the roots.
A solution of vinegar, salt, and dish soap can be a cheap and effective tool against some weeds. A solution of vinegar, salt and dish soap can be a cheap and effective tool against weeds.
Sodium chloride, or table salt, is also a dessicant. Salt is added to weed killer recipes because it is stronger, and kills some plants that vinegar won't kill. It negatively impacts the soil for a longer period of time than vinegar, and it may affect the roots of other nearby plants, as well.
Ground Keeper is a long term weed killer and forms a protective barrier in the soil which prevents most new weeds from emerging for up to 9 months after application.
Mulch. Once you've got the weeds out of your garden, keep them from coming back with a 3" layer of mulch. Straw will work, as long as it doesn't contain weed seeds. Pine straw, wood chips, and bark chips also suppress weeds by blocking sunlight, and they'll break down slowly and amend your soil.
Yes, it's true… vinegar does kill weeds, especially when used along with dish soap. Dish soap, vinegar and a spray bottle are all you need for making your own weed killer. The acetic acid in vinegar “sucks out the water” from the weed, which dries it up.
It is especially effective as a moss killer. For a general weed killer, mix 1 cup of Ultra Blue Dawn dish soap with 2 cups of water in a spray bottle. Shake well and spray on weeds, being careful to avoid overspraying onto plants you want to live. Be sure to spray on a sunny day so that the weeds will dry out quickly.
The Chemistry of Salt: How Salt Works to Kill Weeds
Salt (sodium chloride) works to kill weeds by dehydrating the plants and disrupting the internal water balance of the plant's cells. Since salt is water-soluble, it is most effectively applied when mixed with water as this makes it easier for the weeds to absorb.
Since vinegar kills weeds, it's easy to see how Coke would kill weeds, too. Simply pour Coke on weeds in cracks on the driveway or patio. This is not a selective weed killer, though. So whatever you pour the soda on will likely wither.
Salt can be used as a nontoxic herbicide for killing weeds.
Some gardeners opt to use salt as a nontoxic herbicide, since the substance is natural and unlikely to cause harm to people and pets. As a weed killer, salt works quickly and suppresses regrowth while being an inexpensive, safer herbicide option.