Chemical weed killers are dangerous to use. Their residues can remain in the soil for many years, leaching into groundwater supplies and into ponds and streams through runoff. Safe, organic alternatives are right on your pantry shelf. Homemade organic weed killers are just as effective as chemical herbicides without the dangerous aftereffects and damage to the environment.
Chemical herbicides offer the convenience of spray-on application. However the personal dangers of handling the herbicide as well as the chemical residues are still present.
Homemade organic weed killer can also be sprayed onto weeds. Vinegar or salt solutions are popular organic weed killers, and they are extremely effective. Household bleach is another spray-on organic weed killer. Household bleach is NaOCl, sodium hypochlorite, made up of sodium, oxygen and chlorine. When it oxidizes (evaporates), the compound that remains on the weed surfaces is NaCl, or sodium chloride, which is common table salt.
How Organic Weed Killers Work
Organic weed killers disrupt the cells' performance and damage the cells' structure. Vinegar (acetic acid) and salts cause cell walls to break down. Weeds die quickly from this basic level of destruction.
Salt in high concentrations may remain in the soil for a few weeks and prevent the growth of any plants.Use salt only where you want bare earth.
How to Apply Organic Weed Killers
Make spray applications of organic weed killer when there is plenty of top growth to catch and absorb the spray. This means you should allow several days after mowing for weeds to grow, and use organic weed killer a few days before you mow. You want to be sure there is as much weed leaf exposure as possible when you spray. Try to spray on a hot, sunny day when the mist will dry quickly.
Organic weed killers are nonselective, and they will kill any plant they contact.
Dry Organic Weed Killers
Not all organic herbicides need spray application. Salt crystals can be poured around the base of individual weeds. This is a somewhat slower method, but is quite effective.
Corn gluten meal is another dry organic weed killer. It is a pre-emergent, used to prevent weed seeds from germinating. Corn gluten meal works by dehydrating the weed seeds as they crack open and begin to sprout. It has no effect on existing weeds. This means corn gluten meal is safe to use around existing plants, and it has the added benefit of being a good source of nitrogen.
100 Percent Chemical Free
If you want a no acetic acid, no salt, 100 percent chemically free weed killer, simply heat a large kettle of water to boiling, and pour it directly onto weeds. This will kill anything it touches. Use caution because the steam can damage nearby plants.
Many organic gardeners feel that old-fashioned weed pulling or hoeing is still the most effective way to rid your yard and garden of weeds. Chemical-free weeds can be added to the compost pile where they will decompose and return the nutrients they stole from the soil.