There are a number of weeds that causes problems in the lawn this time of year. Annual weeds such as annual bluegrass, henbit, and chickweed have popped up and need to be controlled before spring. These weeds live one growing season, produce seeds and die. The seeds germinate when conditions are favorable, and the yearly process begins again. Another group of weeds that cause trouble for the lawn this time of year are perennial weeds. These come back each year from the roots, but some perennial weeds come back from seed. The No. 1 perennial weed causing problems now is the dandelion.