by Jacqueline A. Soule

Keeping your hardscapes and decks looking good offers some unique challenges no matter where you live. However in the Southwest, African sumac leaves will stain flagstone, Peruvian apple cactus fruits plop on the patio, and those living in more humid areas have to worry about moss, algae and fungal growth.

If you have pots of plants, the water seeping out the bottom leaves calcium stains like an unsightly botanical ring around the collar. Some folks like the lived-in look of weathered wood, a few leaf stains and moss between the bricks. While a little weathering is fine, you can get too much of a good thing, says Carlos Hernandez, owner of highly rated Go Green Pressure Washing in Slymar, Calif., whose company services San Fernando Valley, Los Angeles County, Ventura County and Pasadena.

"Pressure washing is a cleaning maintenance service that should be regularly scheduled to prevent damage and premature deterioration of exterior surfaces of your home as well as outdoor structures such as decks, patios and gazebos," he says.

Hernandez points out that city environments are rife with things that can deteriorate outdoor structures and landscape features, such as pollution and smog.

"Regular cleaning is needed to remove mold, carbon residues, mildew, dirt, rust stains, fungus, algae, as well as stains from plant debris," he says.

And, Hernandez adds, power washing is about the only way to get rid of the calcium stains that build up under pots. Allen Magee, owner of highly rated Al's Cleaning in Denver, also advocates regularly cleaning outdoor structures, no matter where your house is located.

"Wood decks will last longer if pressure washed every three years prior to resealing," he says. "Artificial decks are very durable and can be pressure washed as often as needed, based on the environment they're in."

You also may consider hiring a painting company for such a task. They often have the proper equipment and trained personnel to pressure wash your patio. Chris Traver, vice president and manager of operations of highly rated Blue Coyote Painting in Phoenix and Tucson, Ariz., power washes concrete patios. When it comes to flagstone, though, Traver says his company advises clients to seek a stone-cleaning specialist.

"Flagstone can be power washed as frequently as once a year, depending on how dirty it gets," he says. "In shady sites, where evaporation is slower, stains accumulate more rapidly."

Magee notes that there are a number of sealers that can be applied to help stone and tile resist staining.

"These sealers will need reapplication every two to three years depending on weather and wear, similar to resealing tile floors or wooden decks," he explains.

Throughout the West, prices for pressure washing hover around $300 for an average-sized patio or deck. And October is a great time to schedule a cleaning - an autumnal "spring cleaning" - just in time for the holidays.

Soule has been writing about gardening in the West for nearly three decades. Her latest book, "Father Kino's Herbs: Growing and Using Them Today," is available through the Western National Parks Association.