Weed killer can be an effective way to get rid of any unwanted plants you may have growing in your yard. But weed killer is normally made up of those pretty potent chemicals. These chemicals may not be something you wish to have contaminating later plants, especially fruit and vegetable plants. So the questions “How long does weed killer last in the soil?” and “Is it safe to eat food grown in spots where weed killer has been sprayed previously?” can come up.
The first thing to realize is if the weed killer was still present, chances are your plants would not be able to survive. Very few plants can survive a weed killer chemical. And the ones that do are either genetically modified to do so or are weeds that have become resistant. Chances are, the fruit or vegetable plant you are growing is not resistant to weed killer. Many weed killers are designed to attack the plant’s root system. If weed killer was still present in the soil, you would not be able to grow anything.
Because of this fact, most weed killers are designed to evaporate within 24 to 78 hours. This means that for the most part, it is safe to plant anything, edible or non-edible, in a place where you have sprayed weed killer after 3 days. If you want to be extra sure, you can wait a week before planting.
Even if there are some residual, non plant lethal chemicals left in the soil after the weed killer has evaporated, these chemicals will have been leeched away after one or two good rainfalls or waterings.
For the most part, the chemicals found in weed killers are not a problem for the home gardener after they have evaporated. This being said, it is always a good idea to completely read the directions and warnings on the label of any weed killer products you buy. The manufacturer will have provided detailed instructions on how to apply the weed killer and when it will be safe to grow plants in that area again.
