Sometimes weeds are a clue to soil or site problems. Correct them so your landscape favors lawn grasses and discourages weeds. For example, ground ivy grows best where the soil surface remains damp. It also thrives in areas too shady for good grass growth. So consider improving soil drainage by aerating—removing small cores of soil—if ground ivy is a problem. And, to allow more light to reach the surface of the soil, selectively remove tree branches in shady areas.