Knit fabric is at its weakest state when wet. Best washed on a gentle cycle in cold or warm water. It can be washed in a machine. Dry in dryer on low to medium heat. DO NOT hang dry it will strain the fibers and stretch.  If you want to air dry it needs to be layed flat. Remove from dryer immediately to avoid wrinkling. If you need to iron it do so on lowest setting with no steam.