Low temp wash (they shouldn't fade in the wash, but it can happen)
Don't hang them out in the sun to dry (so either in the shade, tumble dryer, radiator...)
Don't worry if it does fade.
Real DPM (and dessie, and MTP) fades in the sun.
I saw my cousin's gear before he went to Afghanistan. I saw it after he returned (3 months)- the sun had bleached both his (surplus)dessie DPM and MTP it a really pale colour. And that was just from the sun alone.