Herbicide, Premium Essential Powerful Liquid Herbicide for Removing Wild Herbs Removing all types of Wild Weeds Lawn weeds may die after one application of weed killer. Additional spraying may be required for more mature weeds, for perennial weeds with stronger root systems, or for some stubborn types, especially those with waxy or hairy coverings. Definitions: Mature Weeds = the massive ones on your lawn because you waited too long; Perennial Weeds = hardy weeds, like dandelions, that keep returning. By their nature, they survive season to season, unless you knock them out. Stubborn Weeds = do not readily absorb herbicides or drink it down and laugh in the face of danger 2. Weed killer does NOT work better with a stronger concentration. It is better to spray again, rather than go with a heavier dose which can have negative consequences. 3. Weed killers take time. Some work quickly, within hours you may see dieback. Others work slowly and may take many days before you notice any result. A fast weed killer is usually non-selective and kills everything it touches, especially the lawn. What matters is getting the best killer for a weed. Temperature and the rate of growth affect the reaction of many weeds to chemicals. 4. Liquid weed spray usually provides better weed control than a granular product. You can cover more thoroughly or do spot treatment of lawn weeds with a liquid. 5. Liquid weed killer is sold as a Ready-To-Use product or a Concentrate. The concentrate can be used in a spray bottle, a pump-up tank sprayer or a hose-end sprayer. 6. Sprayers used for chemicals that kill weeds should not also be used for fertilizers. Failure to clean out all residue may kill good plants later. 8.Caution: be certain that the product you choose specifies on the label that it is safe to use on all lawns, or on your grass variety. Some grass lawns are more sensitive than others. 9. A common restriction on weed killing.