Q: What's a good way to remove mildew from outdoor surfaces? It's growing on our porch ceiling and on our side of a neighbor's wooden fence.
A: Bleach water might work, but I would go ahead and make a stronger cleaning solution so the job gets done the first time. Here's the best mixture I've come across, which comes from a housing specialist at Clemson University:
- 1 quart liquid chlorine bleach
- 1/3 cup powdered laundry detergent
- 2/3 cup of a strong household cleaner that contains trisodiumphosphate
- 3 quarts of warm water
Scrub surfaces with a brush and this mixture. Rinse well with clean water and let the surface dry thoroughly.
This is a strong solution, so be sure to wear rubber gloves and don't let it splash in your eyes. You might also cover grass and shrubs with a plastic sheet to avoid damage.
Whatever you do, don't mix any ammonia or ammonia-based cleaners with the bleach. Mixing ammonia and bleach causes chemical reaction, producing dangerous fumes.
While you have the solution handy, you might also check on the underside of awnings, soffits, and carport ceilings for any other mildew.
Source: Ohio State University Extension
