Remove curtains from the window and spot treat any stains with a bar of white soap such as Ivory. Rub the soap on the stain as a pre-treatment.
Place the linen curtains in the washing machine and turn the controls to delicate or hand wash. Pour oxygen-based bleach into the machine if washing white curtains, following the package directions. Regular bleach will yellow the fabric. Add a mild detergent to the washer, following the package directions and run the washer with warm water for the complete cycle.
Promptly remove the curtains after the wash cycle has finished. Hang the curtains to dry, smoothing wrinkles from the fabric. Hang white curtains in a sunny location to preserve their bright color. Remove the curtains from the dry line and re-hang when they are slightly damp.
Iron if needed, following the label directions for the proper heat temperature.