Hi Terry, make a paste by mixing two parts baking soda to one part hydrogen peroxide. Apply the paste to the grout and let it sit for a few minutes. Scrub it into the grout with a tooth brush and wipe off with a wet cloth
These videos give you some great tips on how to do this.
Hi Terry - This is the shower cleaner that we use to help keep grout and tiles clean and minimize the mildew - it works on kitchen grout too. Hope this helps! Hugs, Holly
PS - We have a FREE eBook with recipes for all of my homemade and all-natural cleaners. You can download it here --> https://pinkfortitude.com/thank#GreenClean
The Best Way to Clean Grout-EVER!!! | Hometalk
Painted Tile Grout Refresh with grout pen