It only takes one weed to ruin a beautiful lawn — but when is there ever just one? Get a handle on some of the most common weeds by learning how to identify them and how to kill them. (For all products, follow label instructions. ) Dandelion Dandelions have green leaves edged with ’teeth’ that grow mostly flat to the ground. Bright yellow flowers fade to form a white puffball. They appear in spring and fall in lawns that aren’t as full and healthy as they could be. Treat it. Mow high and feed your lawn regularly to promote healthy grass. For a dandelion infestation, use Scotts® Turf Builder® Weed & Feed3. It feeds to promote a thick lawn and kills existing dandelions, tap root and all. If you have a St. Augustine or Centipede lawn, use Scotts® Bonus® S Southern Weed and Feed2. Spot-spray a few dandelions with Scotts® Spot Weed Control for Lawns, which kills dandelions without harming grass. Crabgrass Crabgrass is a grassy weed with blue-green leaves that form a crab-like circle. Though it doesn’t usually become noticeable until the summer, crabgrass germinates in the spring, typically in thin or bare areas of a lawn, or in dry soil. An annual weed, crabgrass will die with the first hard frost in the fall. Treat it. Once it appears, it can be difficult to control, so prevention is the key. Feeding your lawn will also help. In early spring, apply a pre-emergent herbicide (one that stops crabgrass from developing) by feeding your lawn with Scotts® Turf Builder® Halts® Crabgrass Preventer with Lawn Food.