According to the Sunset Western Garden Book, Chasmanthe grows in zones 13, 15-24. These are growing all too well in zone 14. Since they spread both by seed and corm, they can and do multiply rapidly. My fault! I used to wait until they were dry to mow them, "DUH", and then I'd rototill........If only the deer would snack on them instead of the garden! But, they do need to be mowed (the chasmanthe plants, not the deer) because they would be a major fire hazard.