perpetual/walking onions

i chucked some seeds in a pot last autumn and while i was clearing the grenhouse yesterday i noticed they are about 3" high  . i will be putting them down the lottie once the weather warms up.
this may sound stupid but......how do i use them, do i pull them up, bulb included, or do i cut off the green stalks, like chives.
 

You can use the bulb and stalk in things like stirfry's or use them like salad onions.