As far as cleaning goes, hand washing, when done properly, is by far the best way to preserve the color and fabric of your hakama. And believe it or not, hand washing can even clean your hakama more thoroughly than a washing machine or dry cleaning.
To wash your hakama by hand, place the hakama in a tub. The tub can either be a bathtub (make sure it’s clean ;)) or any other type of tub large enough to accommodate the length and width of the hakama lying flat. I only have a shower at home so I use a large plastic tub that I originally bought for storing stuff.
Fill the tub with enough cold water to cover the hakama and add some detergent-free laundry soap such as Woolite.
Next, begin gently stepping on the hakama to allow the soap to penetrate the fabric. Continue for a few minutes.
Rinse the hakama thoroughly.
To remove excess water, do not wring the hakama. Instead, empty the water from the tub and, laying the hakama flat, run your hand down the length of the hakama toward the drain. If you don’t have or aren’t using a bathtub, don’t worry. You can skip this step.
Finally, using clothes pins, hang the hakama up to dry upside down, preferably without folding it over.