depends on the plant, and how much you're bending it, some like to snap back into place and have to be tied down, or if you're trying to make a pretty big bend, its better to tie it down for a few days, once the shoots on the branch start growing upwards , you can usually untie them and they'll stay. mine will usually stay where i put them, but it sometimes takes 3 or 4 "sessions" to get it to grow the way i want