Agave filifera is a compact medium-sized agave with tough narrow leaves that have many attractive curling white threads along their margins and a sharp terminal spine. Usually forming a single growing point it does - on occasion - form offsets and with time will develop a short woody trunk. Usually cited as being frost hardy down to about -8 C, I have grown it outdoors for many years in a sheltered position with a large Cordyline forming overhead protection and where - during at least two winters - temperatures fell to -14 C. The plants, grown in terracotta containers, survived with no damage at all and I didn't lose one ... or at least, not to cold; one container was however stolen - never to be seen again. It's good to know exotic gardening is catching on ...