Hi Gwen, you can purchase grass feed that literally screws on to your hose and feeds the grass nutrients and fertilizer when you water it.
Miracle Grow makes a lawn fertilizer product and a hose sprayer attachment that you use to apply the product. It works very well.
We use the Scott's 4-step program. My husband uses a walk-behind spreader to apply it on the lawn. Our grass is lush and green. And no weeds. He only puts it on the front yard. Our backyard is very big and would be expensive. Plus we have kids and dogs in the back.
We use weed and feed. And water, of course. :)