In our area, when the forsythias start to bloom it is time to treat your lawn with pre emergent weed control. These herbicides must be applied before weeds emerge to have any real effect, since they work by preventing weeds from germinating in the first place. Many people don’t think about the weeds until they actually see them, and by then the window of opportunity to prevent them has passed. Treating too late is not effective for weeds that have germinated; they will need a post-emergent treatment. However, due to the long weed germination season in our area, two pre-emergent applications are ideal. So a late first application is better than not at all!
Keep in mind that you’ll never completely get rid of all the weeds in your lawn. The wind will blow weed seeds from nearby, birds will deposit them and people walking from one lawn to the next will transport weed seeds on their shoes.
Our thought is that a healthy and vigorous lawn will choke out weeks. Timely fertilization applications throughout the year will achieve this!