When your lawn is about 50% green (mid-March) you can apply Ferti-lome St.Augustine Weed and Feed to kill young tender weeds and to prevent warm season weeds from emerging. This is safe on Centipede grass. It will help with Chickweed, Dollarweed, and Oxalis. If you have large Clover, Dandelion and Spurge we would recommend waiting until the lawn has entirely greened up (April) and applying Ferti-lome WeedOut Plus Lawn Fertilizer. Bring in samples of your weeds for additional help.