Oxi-Clean and an old electric toothbrush.
Try 2 things: Mix baking soda and Clorox. Apply with toothbrush. OR use non-gel toothpaste. Scrub with toothbrush.
I Use Tilex, let it sit then scrub with soft scrub and a scrub brush. Once clean, be sure to seal. Really helps.
Hi Roberta - 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 - I'm getting ready to release a FREE eBook with recipes for all of my homemade and all-natural cleaners. If you want to know when it's released, you can get it here --> https://pinkfortitude.com/thank/
Whats better than toxic Clorox bleach to use on dirty grout is hydrogen peroxide which eliminates the mold pores and prevents mildew build up. Clorox cleans it but the peroxide will penetrate deeper and help keep the black mildew at bay and doesn't emit the strong toxic fumes as bleach does or ruin your clothes.