With proper care, a wool blanket will last for many years, even if used for many hours every day. Here are a few tips to help you prolong the use of a wool blanket:
Beat and brush the blanket: Every few days, slap the blanket against a door, pipe, fence, etc. Then use a soft to medium stiff horse brush (not a metal curry comb), and quickly brush the hair and dander from the blanket.
Wash the blanket: Every 60 to 90 days, wash the blanket in a tub of cold water. For best results, put your blanket in a tub of water and let it soak for at least an hour. Then, as best you can "wring" the blanket in the water, then "wring" it out of the water.
Hang the blanket over a rail: (like the top rail of a fence), and with a soft to medium brush, lightly brush the blanket on both sides. Let the blanket air dry completely, then slap it against a door or fence until it feels as soft as a brand new one.
NOTE: It is best not to use soap when washing wool blankets. The blanket will retain much of the soap (even soaps made specifically for wool). When the blanket becomes wet with sweat, the residual soap may seep throughout the very porous wool, and irritate a horse's back.
After a few washings, the color will of course begin to fade. This has no bearing on the usefulness of the blanket in serving it's true purpose. You might find that you prefer an older, faded, soft blanket next to your horse's back. After all, the concept is to protect your horse's back and keep them comfortable.