A study done at Michigan State University shows that you can forget about raking, blowing, and bagging leaves. Instead, just mulch them. MSU studies found that homeowners can attain a nearly 100 percent decrease in dandelions and crabgrass after mulching fall leaves for just three years. In addition to reducing the occurrence of weeds and the need to spend money on weed control products, mulched leaves keep the soil warmer in winter and cooler in summer and the nutrients provided by mulching reduce the amount and expense of fertilizer need to achieve green-up in the spring.