How can I seal grout that was never sealed?

Make sure it's clean and dry, then use a grout sealer according to the package directions. I've done this with no problems.

Like Ann said clean them really good. If you're not happy with the color once they're cleaned, you can stain or paint them before you seal them. The instructions will be on the package, follow them and you shouldn't have any problems.

Hi Martie, You can seal the grout the day after you applied it or 100 years later. If it isn't dirty, seal all three sides of the shower with a tile sealer or masonry sealer. That will make the grout water-resistant, if not waterproof, and help prevent the growth of mold and dirt

Scrub it clean and reseal. I actually reseal my floor tile in my entryway every year. It gets a lot of foot traffic.