White rocks add an eye-catching focal point to the garden, catching the shifts in light at different times of the day and contrasting sharply with deep green summer foliage. Whether you've installed a white marble bench, a white granite accent boulder or used white crushed stone as a mulch or walkway landscaping element, just as predictably as that fresh white shirt, it will one day start to look a bit limp and dirty. Laundering rocks, however, is not so easy. While single stone elements can be scrubbed with a brush, washing crushed stone takes some heavy lifting.
Fill bucket with hot water. Sprinkle baking soda on marble furniture or on marble or white granite accent rocks. Scrub with scrub brush dipped in water, then rinse with more hot water. Repeat, adding a little non-chlorine bleach to clean any remaining stubbornly dirty or mildewed spots. Spray clean with hose.
Spray crushed white landscape rock with hose or power washer, taking care to avoid sending rocks flying. Wear protective gear--long-sleeve shirt, heavy pants, work boots, goggles and gloves--while handling rocks.
Let the landscape rocks dry and assess whether they are clean enough for your needs and their intended aesthetic purpose. Fill a plastic tub halfway with water and add 1 cup of non-chlorine bleach per 10 gallons of water to proceed with further cleaning.
Shovel rocks into wheelbarrow, then shovel them from the wheelbarrow to the tub with water and bleach. Dump debris that remains in the bottom of the wheelbarrow into trash or compost pile. Let the rocks soak overnight.
Place the plastic tub with holes in it over the remaining plastic tub. Shovel the rocks from the soaking tub into the tub with holes in it. Spray with hose or power washer until clean.
Return cleaned rocks to the landscaping, and dispose of water and bleach solution safely--pouring it into your tub if you have sewage treatment services, or into a sand filter, or utilize household hazardous waste disposal services for removal.