Ronnie from Greenville, Ms writes
For most of the country Pennant Magnum would be applied in the spring and/or fall and sometimes summer, not based on when the lawn greens up. Pre-emergents prevent weeds from germinating and growing and so if you already see weeds in your yard then it is definitely too late. Most of the weeds should have germinated by now so it would be too late to apply. However, we are not sure where you live and we are not familiar with every part of the country. We recommend that you call your local cooperative extension office, and they should be able to tell you the exact times of year to apply the pre-emergent in the late fall and early spring so you can treat at the proper times in the future.
Answer last updated on: 06/21/2016
