Press mixture firmly into jars until the water level starts rising.
Put the lids on and leave the jars at room temperature for 3-7 days. Open the lids every day to release the carbon dioxide that form as a byproduct of fermentation. If the water level rises, drain some off. If the vegetables rise above the level of the water, pack them back under the water.
Taste the bok choy kimchi after 3 days. It should taste pleasantly sour. If not, continue to let it ferment and taste it every day until you find the taste acceptable. Transfer to the fridge where it will continue to ferment (and the taste will change!) albeit at a much slower pace. It will last for at least six months.