I have a number of varieties of Asian clumping bamboos and several Himalaycalamus hookerianus cultivars were quite heavily damaged nearly a month ago by about a week or more of unusually low temperatures for my area. I live in a particularly cold microcrlimate of the San Francisco mid-Peninsula, and my thermometer logged a low of 17 one night, and many nights in a row around 20-22, with the result that most of the leaves were badly damaged on Himalaycalamus hookerianus 'Little Blue', half the leaves badly damaged on another larger specimen, and many damaged upper leaves on tall newer canes of H. hookerianus 'Teague's Blue' (which was planted in the most sheltered location). Now most of the damaged leaves have fallen off, and one plant is leafless! So I'm worried I will lose these gorgeous plants, or perhaps the most damaged one. Web references suggest H. hookerianus is hardy to 20 degrees. Anyone have any experience to give me some hope mine will be okay?

Other similar bamboos I have that didn't particularly suffer in the cold spell are: Drepanostachyum sengteeanum, Himalayacalamus asper, Himalaycalamus falconeri 'Damarapa', and Borinda fungosa.