how to keep a lawn healthy

Many of my new customers had landscapers in the past. They had nice thick green lawns with no weeds. This spring I started mowing and now there are many weeds and the lawn isn't as nice as it used to be. I put down fertilizer on some lawns and I'm about to put lime Down. How can I keep these lawns green healthy and weed free?

All things added to a lawn need to be done by calandar for the area the lawn is grown in as well as the type of lawn it is. My guess is chemicals should have been applied and watered in some time ago before the weeds began to germinate and sprout in the lawn. Most lawns that look very nice have a good pre and post emergeant weed control program. Fertilizer is a good thing if plenty of water is available but can make weeds grow very well just like the grass. around here unless the lawns are very well kept cool season grass is not fertilized. Warm season on well kept lawns is fertilized but only during the early but hot part of the summer. Buffalo grass if well kept is sometimes not fertilized until July. Most Buffalo grass and Bermuda grass around here has never seen fertilizer unless a dog crapped on it or in some cases on the buffalo grass since a buffalo, cow, horse etc. dumped on it. Grass thrives on fertilizer, but so do weeds. None of the fescue or rough bluegrass out to the city lake has ever been fertilized and it was planted in the 1950s. It has never been watered or sprayed for weeds either. But it is not a nice lawn. Just a nice looking wildlife area so to speak. Kind of like a mowed cow pasture.