According this site wool rugs need regular cleaning after a certain period since they start getting duller and the fringe becomes bad after a duration of use without cleaning. A lot of dirt and grime often tend to collect in the wool's fibers over time. Hence, you can maintain your wool rug through the following simple steps:
Step 1: Take the wool rug outside and shake off the dust from it. Ensure that it is dry while shaking off the dust since wet rugs tend to embed more dirt than removing. You can hang the wool rug over a clothesline and use a broom or any convenient material to beat the dust off it.
Step 2: Position the wool rug in a flat surface and run the vacuum cleaner over it in a "V" manner. Using the vacuum in "V" helps alternate efficiently the direction of the vacuum and prevents crushing the wool rug's fibers. Repeat these process 3 to 4 times over the wool rug. To ensure that your wool rug is clean and free from dust make it a habit of vacuuming it once or twice a month. Also, ensure that the underside of the wool rug is vacuumed at least once every two months. Ensure that the vacuum is set to a high height so as to avoid excessive agitation of the rug.
Step 3: After all the dirt has been removed you can shampoo the rug. Use a mixture of cold water and rug shampoo to sponge the rug. Use the sponge firmly to wash the fringes of the rug. You can also use a mild liquid soap instead of rug shampoo. Ensure that you wet the rug properly while brushing over it in linear motions. Then use clean water to clean all the soapy solutions off the rug. (source)
Step 4: Ensure the rug is dried immediately. Wool rugs often need extensive drying hence it is advisable that you either squeeze any excess water off it or hang it under the sun to dry. Don't use a dryer to dry it, however, you can use heaters to help speed up the drying process. Ensure that both sides of the wool rug are dried properly before returning it to the floor. In case your wool rug feels stiff after drying you can vacuum it once or gently brush it for it to regains its softness. Thus, following the above simple steps you will have ready know how o how to clean a wool rug.