Spring is a great time to think about dethatching your lawn, this will also help pull up all of those leaves and acorns that you missed last Fall. Dethatching is very important to your lawn, once the thatch becomes to thick the fertilizer and other materials that you are putting down will not be able to reach the root system and do what they need to do to keep your lawn healthy. Water will also have a hard time getting through. Removing the layers of dead grass can be done quickly with a powered machine available at most rental centers or you can do it by hand with a special rake designed for removing thatch if the area is small enough, also most professional landscapers offer this type of service. Make sure that you do your dethatching before putting down any crabgrass preventer, once this is in place you do not want to disturb it for at least 90 days. Late summer and early fall is fine for lawn dethatching also, just make sure that the lawn is not stressed out due to drought. Fertilizing after dethatching will help green up the lawn and get those roots growing.