Growers monitor their cannabis flowering stages week by week. Don t panic - don t use a Feed, Weed and Moss Killer product on a new lawn These weeds will be shallow rooting; you can pull them out by hand Or wait until the 6-8 week mark to mow them out If the weeds are persistent and reoccurring, use a selective herbicide to spot-treat them. a pea at 2cm, a ganja seed at 1cm.  Source: <a href=https://theschooltour.com/?p=14143>https://theschooltour.com/?p=14143</a>