I planted a plot last spring with alfarack and provide clover and chickory, immediately after which we had one of the driest summers ever. The growth did start ok but because of the weather it did not flourish, however the weeds and grass did. Now this spring I would like to overseed with clover and alfalfa, but I also want to get rid of the weeds and grass. I did mow last year a couple of times but it did not help. How early can I spray poast or vantage but still get the seeding done early enough. Another plot I want to do this year I tried to plant a couple of times before but the weeds and grasses ruined that too. I intend to spray that with roundup this time, then plant alfalfa and clover. Once again how early can I effectively spray and still seed at the proper time. Both these sites have been soil tested and are right on target. Thanks for any advice.