Remove large debris such as leaves and branches immediately using a broom as, not only can they cause damage themselves, but mildew can grow on them and then spread to your awning fabric, even mildew resistant fabric.
Rinse off your awnings regularly to wash off pollution, tree sap, bird droppings, or insect spray. These can all degrade the color, strength, and integrity, of your fabric over time due to their chemical properties.
Dust, sand, and mildew can degrade the fabric by physically abrading, or teasing it. A grain of sand typically has 14-17 abrasive, cutting edges on it, dust is similar, and mildew will grow into the fabric threads decreasing its integrity and strength, as well as degrading the color. Rinse off the first thing in the morning to allow it as much time as possible to dry.
Do not use strong detergents to wash off your awnings as this may effect the life span of the UV protection, waterproofing, and other sealing agents applied by the manufacturer to the fabric. Rinse off any detergents, or soaps, thoroughly. Contact your awning manufacturer for advice on what soaps you can use, in what concentration, and then be conservative.
Only you can decide how often to maintain your retractable awnings; the more dusty, or windy, the environment, or the more trees and shrubs nearby, the more often you will need to maintain them. The closer you are to the ocean, sand, or pollution, the more frequently you will need to rinse them off. Make awning maintenance a part of your regular home maintenance schedule (example – mow your lawn, and hose off your awnings). By following the awning maintenance guidelines discussed here you will be able to save money, and enjoy your fabric awnings for many years with the same vibrant look of new awnings.