By Robert Cox, Colorado State University Cooperative Extension, Horticulture
Using bleach to kill weeds is not a good idea. Bleach is sodium hypochlorite. It has a pH of about 11. Application of bleach to weeds will raise the pH of your soil and adds sodium to the soil as the bleach drips off leaves. Both of these circumstances make it harder to grow desirable plants in the treated area.
If you want to use something from your household to kill weeds, it would be much better to try vinegar. Sprayed on leaves of weeds, vinegar dissolves the cuticle ("skin") of the leaf, allowing the plant to dry out. This works well on annual weeds. Perennial weeds like dandelion, bindweed and Canada thistle will recover from this treatment to send up new shoots and leaves.
Ultimately, it is usually better to use an herbicide according to label directions than to use a household product not intended for that use. Many herbicides are intended and able to alter or interrupt a specific plant physiological process, thus killing the plant.
Photo: Judy Sedbrook
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010