Wash: the safest way to wash is with cold water and mild detergent (as ph neutral as possible). But earthy materials are always in flux-- I truly accept and enjoy the changes of natural colors over time. It feels alive and adds transformative beauty to the piece. 

Dry: The way you dry will yield different results. Here are the pros and cons of different drying techniques...

Machine drying: 
Pros: gets the linen super soft; quicker dry time (<20 minutes if put in the dryer alone with a dry towel)
Cons: will cause small amounts of shrinkage each time; high heat or repetitive heating will likely cause the natural colors to fade little bits over time. But this is all a part of the natural life cycle, and faded earth tones are still very beautiful in my opinion. 

Tips: Mitigate this by only drying 80-90%, and letting it air dry the rest of the way. If you are worried about shrinkage, give each section little tugs when they are still at 80% dry in order to return them to their original size. 

Air drying: 
Pros: will likely increase how long you get the original depth of shade of the dye color
Cons: Longer dry time, takes up space (you shouldn't let it dry in direct sunlight if you want to reduce fading), and fabric typically feels a little bit crispy to the touch once it's dry. 
Tips: Mitigate this crispy feeling by rubbing the garment into itself. Ball it up in your hands and sort of scrub it with itself. This loosens up the fibers and gets them feeling much softer! 

How I treat my own naturally dyed linen clothing: 
I machine wash with gentle detergent and with other clothing of like colors. I machine dry with the same load, but remove from dryer when 90% dry (I usually check it at around 20-30 minutes in). Stretch out any pieces that look too small, like sleeves, skirts, pant legs, etc. But I dont go overkill because linen naturally will stretch back out after about an hour on an active, warm body.