There are a lot of variables when it comes to weed growth but we will start simple. In the spring, around the same time as your first mow, you should start off by feeding your grass with a good fertilizer like Scotts Turf Builder Lawn Fertilizer. (be sure to mow higher in the spring to encourage healthy roots I would recommend over 2?) If your grass is healthy and well fed, then weeds will have a harder time taking over. Once you do see a weed pop up, you may want to spot-kill them with something like Ortho Weed-B-Gon MAX? Weed Killer For Lawns. And if they have already become a big problem for you, you could try something like Scotts? Turf Builder? Weed & Feed. Be sure you calibrate your fertilizer spreader correctly, usually there are instructions on the back of the fertilizer bag. Don?t forget to give your grass a good watering after to prevent a burnt lawn too. Watering your lawn very well 1-2 times per week will encourage lawn health and keep your weeds at bay!