Crabgrass is one of the most common lawn pests that landscapers and homeowners have to deal with. It can be found all across the United States and is also known as crowfoot grass and summer grass. Crabgrass is very hardy and is very hard to get rid of, except in high elevations and areas that are very dry. Even the healthiest of lawns and flowerbeds can expect a little crabgrass within the turf.
Pull up all crabgrass out of your planting beds. You might be able to eliminate the weeds without using chemicals that can potentially harm your flowers. Use a trowel or shovel to get down to all the roots and fill the holes back in with surrounding soil.
Apply plastic sheeting before you begin planting your beds. The plastic sheeting will keep out all weeds. Place the sheeting underneath the soil. Use an all-purpose soil on top of the sheeting in which you will plant your flowers.
Spray your crabgrass with an herbicide to destroy the existing crabgrass. This should be done in the early spring before crabgrass begins germinating. For best results, use a post-emergence pesticide, which is effective on crabgrass that has already been established. You can find this at any home improvement store. Follow the instructions exactly as stated on the herbicide.
Water your flowerbeds only when it is absolutely necessary. Most flowers are capable of withstanding a degree of drought, but crabgrass is not. Frequent use of sprinklers will encourage crabgrass to grow. Water your flowers with 1 to 2 inches of water, which is just enough to reach the roots. Do not water your flowers again until the soil is completely dry.
Fertilize your flowers with a good nitrogen fertilizer. Use a quarter pound of fertilizer to 125 square feet of bedding. This should be done in two separate applications--one in the early fall and one in the late fall. Fertilizing in the hot summer months will only feed your weeds.
Use 2 to 4 inches of mulch on top of your flower beds. This will help to hold moisture around your flowers but will help prevent weeds from growing. As the mulch becomes established in the beds, it can encourage weed growth. Use a rake to spread the mulch every couple of months to break apart the weed roots and keep them from growing.