Source:  http://www.housecleaning-tips.com/how-to-clean-drapes.html

How to clean drapes

Many people never wonder how to clean drapes, curtains or other window treatments in their home. This is because they are often overlooked when housecleaning.
During spring-cleaning or fall cleaning, they remove every speck of dust and dirt from their home but overlook their curtain and drapery cleaning. This happens because their window treatments still look clean, even if they have been hanging for years.
Window treatments are important for their aesthetic beauty; they protect your furniture from sun damage and give you privacy and comfort. Draperies are usually a heavier, lined fabric that extents to or close to the floor, whereas curtains are often lightweight and unlined.
Draperies, curtains and window treatments collect a huge amount of dirt over time. Dust, oil, pollution, smoke, pollen, heating fumes and bacterial are just some of the dirt that they retain. Even though they look visually clean, drapery cleaning is certainly a necessary part of housecleaning.
How to clean drapes starts with daily care. In the evening, when you draw your drapery panels or lined drapes closed, gently shake them, to keep dirt and dust from lodging in the fabric.
The most important drapery cleaning tip to follow is, vacuum your drapes often, using a handheld vacuum with a soft brush attachment. Weekly vacuuming is best but if that is not possible, vacuum your drapes at least once a month.
When you are wondering how to clean your drapes, there are certain circumstances where you need to have them professionally cleaned. Never wash draperies if:

* they are not labeled washable
* the fabric is faded and weakened by sunlight
* embellishments and trims are not colorfast
* drapes are pleated
* the lining and drapes are different fibers or only one is washable
* they are too large or bulky to fit properly into your washing machine

This is how you should clean drapes or curtains labeled washable.
Either hand wash, if they are small, or machine wash using the short, gentle cycle. Use cool water and mild detergent but never overload your washing machine, as the drapes will not clean properly.
Rinse thoroughly and gently and then either line-dry, out of direct sunlight or tumble-dry on a delicate or air setting.
Remove your draperies immediately from the machine once they dry. Touch up with your iron if necessary, but press on the reverse side, not on the front of your drapes.