Perhaps the best answer to this question is to pose another. If you took your best shirt or best dress and hung it from a flagpole how long would it still look good? Flags, like clothing, are simply well made material prone to the same damaging sun, wind and rain effects.
But there are preventive steps to take that will keep your flag looking sharp.
* If it is a really windy day, take your flag down. Wind places great stress on the fabric and stitching and leads to small fraying at the fly ends.
* Avoid flying your flag in the rain. Additional water weight greatly increases the strain on your flag's material.
* Be careful where you fly your flag. A nearby tree or other rough surface will rub against the flag and lead to small tears in the material. Once a tear develops it will only get worse.
* Flags flown in cities are prone to damaging smog and exhaust fumes which will dim the colors and lead to deterioration. You can minimize smog and exhaust damage by limiting the hours each day your flag flies, and taking your flag down during especially smoggy times.
* Continuous day and night display will shorten flag life. Consider taking your flag down each evening.
* When you store your flag, make sure it is dry before folding. A folded wet flag leads to mildew and damage to the material.
* Consider a nylon or polyester United States flag. While cotton has the traditional look and feel many people desire in their flag, it is the most delicate material, prone to the damaging effects of the elements, and leads to quicker faded colors and fraying.