There are Dendrobium species hardy as far north as zone 9, though most are hardy in zones 10 to 12. In these regions, it is possible to grow them year-round as container plants on decks, patios, or courtyards. But like all orchids, dendrobiums are sensitive to cold, and temps that fall below 50 degrees are likely to damage them. Be prepared to move your potted orchids indoors when temps turn cold.