The key to effective crabgrass control is to stop it before it becomes a problem. For those who have already noticed it in their yards, there may be very little that can be done until the following spring. Fortunately for those who wish to control crabgrass, the winter does a good job of killing off the grass in most locations.
However, once it is in a yard, crabgrass will re-emerge during the warm summer months and into the fall. Therefore, the best time to implement a crabgrass control strategy is before it emerges. While it may be tempting to think that, since it is not seen in the spring, it has gone away, this would be a mistake. Its seeds stay dormant until warmer temperatures so even if it is not seen, crabgrass control is still necessary if it was there the previous year.
A number of pre-emergent herbicides can be used for crabgrass control. Spraying the lawn with such a herbicide will help kill any crabgrass before it begins to grow. However, once it starts to grow, the pre-emergent herbicide will have no affect on the crabgrass.
Also, because crabgrass is not shade tolerant, keeping the lawn mowed to the highest recommended height should help. This method of crabgrass control requires no harmful chemicals and effectively chokes out crabgrass in a natural way. However, it may not work in all cases.
Once it has emerged, there is very little that can be done to control crabgrass without substantially harming the desired grass species. Removing it by hand is one option, though it is very time consuming. If it is particularly bad in a certain part of the lawn, removing it with a shovel and resodding is an option. However, this cannot be done with seeding if it is during the warmer months, simply because the crabgrass will also come back. During cooler months, re-seeding may be an option.
Those who have gardens have different problems when it comes to crabgrass control. Gardening often means there will be bare spots in the area where the garden is and herbicides may keep some of the desired fruits and vegetables from growing. The best option in this case is to remove all grass out of the garden through hand weeding.
Crabgrass control also is aided by making sure there are no bare spots in the yard. Requiring ample amounts of light to grow, crabgrass will naturally be attracted to bare ares of a lawn, especially those not shaded by other vegetation. Overall, effective crabgrass control requires making sure the desired grass is healthy and growing full in all spots in the yard.