Getting rid of wide blade grass in your lawn can become a pretty big job, but can be easy if you pick the perfect day to do it. These grasses usually grow all season long, starting in the spring and continuing throughout the fall. There are many different types of wide blade grasses, with the most common being crabgrass.
Purchase crabgrass killer, but read the packaging to make sure it is suitable to use on your particular lawn grass type. St. Augustine and centipede grass will almost always die if they are hit with crabgrass killer, so if you do not want to bring your lawn down with the crabgrass, read carefully, and find a "selective" killer that will kill only crabgrass.
Mix the concentrated crabgrass killer and water in the proportions specified on the packaging. Pour the mixture into your tank sprayer. Some crabgrass killers come with an applicator bottle that you can use instead.
Rake the crabgrass to break up some of the leaves. This will enable you to get an even coat of crabgrass killer all over the plant.
Spray the crabgrass with the killer and wait until it dies. This could take only a day or two, or (especially if you have well-matured crabgrass) you might need another application. Repeat the process if necessary.