Is there anything more gratifying than a beautiful garden when you just happen to be the gardener? But one trip to the garden center to pick up soil amendment, weed cloth, and weedkiller can pretty much zap all of that joy with its hefty price tag. That’s why I love today’s tips and tricks—including, back by popular demand, homemade weedkiller. Garden Vitamins While you may have no use for spent coffee grounds, your garden will love them. Used coffee grounds are like megavitamins for the soil. They’re rich in phosphorus and magnesium—important nutrients that help plants grow. It’s easy to just sprinkle coffee grounds (wet or dry) around the plants and work them into the soil. They’re even the right color. If you’re not much of a coffee drinker, don’t despair. Many coffee shops package up their used coffee grounds in the bags that the beans originally came in and …