Most crabgrass control products are based on the idea that crabgrass is an annual, i.e. it grows for a season, produces seed and then dies due to cold and frost. The seeds survive the winter, germinate in spring and start new plants. Crabgrass control products are applied in spring to stop the germination of the seed, i.e. they are germination inhibitors. Unfortunately, here on the Central Coast our winters are often mild. These mild years allow crabgrass to act like a perennial, i.e. grow in a vegetative state from year to year. Under these conditions crabgrass killer will not work because the product will not kill plants. What can you do? There are no easy solutions. If the crabgrass problem is severe, meaning that most of your lawn is crabgrass, you should really consider having a crabgrass lawn. As a friend of mine said: “Fertilize it, mow it, and call it home.” A second option is to kill all the grass and start over with new sod. Notice, I did not say seed! If you clean off the dead lawn, bits and pieces will remain. Some of these will most likely be crabgrass seed. If you seed new lawn, the residual crabgrass seed will also germinate, and in a short time you will have the same crabgrass problem with which you started. Therefore, use sod for your replacement grass. Before the sod is laid, apply crabgrass killer to the bare soil to prevent residual seed germination under the new turf. Finally, there is hand-weeding. Yes, I have done it. I had several patches of crabgrass invading my lawn. By hand-weeding periodically over a period of two years, I was able to eliminate the infestation. Now I walk over my lawn periodically to check for crabgrass and hand-pull the few individuals that attempt to reestablish an infestation.