(Image credit: Shutterstock) A patchy, dull lawn with more weeds than grass doesn't have to stay that way. Most lawn problems aren't caused by bad soil or hopeless grass genetics; they're the result of basic care mistakes that are surprisingly easy to fix. Cutting grass too short, watering too frequently but too shallowly, and skipping fertilizer all create the perfect conditions for weak, struggling turf. Grass that doesn't get what it needs can't compete with weeds, resist disease, or maintain that deep green color everyone wants. Article continues below 1. Mow at the right height Most people cut their grass far too short, thinking shorter means less frequent mowing. But scalping your lawn removes the leaf surface grass needs for photosynthesis, weakening the entire plant and making it vulnerable to weeds and disease. Never remove more than one-third of the grass blade height in a single mowing . This rule maintains enough leaf area for the grass to produce energy while still stimulating new growth.…