i have bought ginseng that was held up to 5 years with just a little visable change in apperance.as far as potency i just dont know.you will loose some weight over time but not very much,maybe half an ounce the first year.kentucky law allows diggers to keep ginseng forever if they want.dealers must sell by april,or get weight reciepts to hold over until next year.keep in mind when i talk ginseng i mean regular woods dug ginseng,not roots as big as your hand.there is so much tame ginseng being mixed with wild ginseng i just dont buy any large roots that look even slightly odd.hope this helps