It is always better to do a repeat application than to use a stronger mix, thinking it will work better or faster.
Do not use these concentrates in a hose end sprayer unless it is the type that allows you to dial in the setting for the correct concentration. The liquid fertilizer sprayers do not permit this.
If the label says “non-selective”, it will kill anything it contacts. You want to use a “selective” killer intended to specifically kill crabgrass in a lawn.
If the crabgrass you are spraying is young, it may die after one treatment. More mature weeds may require one or two repeat applications. Follow the interval schedule on the label for the repeat time.
Don’t mow the lawn prior to applying the chemical, since you want more leaf area of the weed to soak up the spray.
Don’t water after spraying for 24 hours, and if rain is forecast, it may be better to wait and apply the treatment after the storm.
Don’t ruin your spray equipment. Thoroughly rinse the container immediately after use. Avoid leaving residue that could clog the unit or affect plants later.
Don’t mix more product than you will use in one application. Potency can diminish if the mix sits for days before it is used.
It is not uncommon for a lawn to show discoloring after being sprayed with chemicals for killing crabgrass. This should not be a cause for concern, if you used the appropriate dosage.
Using Other Weed Killers To Kill Crabgrass
Many homeowner like to use a weed and feed fertilizer. These products are designed as a convenience to help control broadleaf weeds in your lawn, while you fertilize. They will not kill it.
If you find a granular weed and feed that specifies it will kill crabgrass, use it if you have a minor problem. Realize however, that the granules have to land and stay on the weed to be absorbed. This means many crabgrass plants could be missed. A liquid spray allows you to cover the weeds more thoroughly.