I am often asked whether Tillandsias can cope with cold temperatures and as with most plant questions the answer is, it depend
Tillandsias grow in a wide range of habitats in nature and many of these are at altitude or in areas that experience low temperatures. If you are growing in a cooler climate then choice of species is important.
As a general rule most Tillandsias will thrive in temperatures from 10to 35°C. Our nursery goes down to 7 °C without any damage. Tillandsias are not considered frost hardy and we would always recommend protecting them from frost. You can do this by moving them inside or to a protected veranda or greenhouse in winter or use frost fleece when the forecast is cold. One of the benefits of Tillandsias is that you can mount them in portable settings so you can move them inside for the coldest periods.
Whilst many Tillandsias will cope with cooler temperatures you should carefully regulate watering, a Tillandsia that is wet and then gets frost is much more likely to be damaged so only water when the weather is warm and dry.
There have been a limited number of studies on frost hardiness but the article in this link has a handy table to list those Bromeliads that or more or less cold-hardy.
Those most likely to cope with colder temperatures are T baileyi, fasciculata, recurvata, tenuifolia and T usneoides. Others that can also withstand periods of cold temperatures are T brachycaulos, capitata, festucoides, tricolor, paleacea and juncea as well as the Wallisias. Those that seem to suffer the most in cold temperatures are those used to hot conditions like T tectorum and the bulbous species such as T streptophylla, caput medusae and pseudobaileyi. This would suggest that those plants that hold more water in their pseudobulbs are more vulnerable.
Our Tillandsias are grown in Southern KZN in sub-tropical conditions, so we recommend that if you live in a place with colder winters you try to buy in Spring or summer to give them some time to adapt or give them some extra protection their first winter. Tillandsias are extremely adaptable plants and there are growers in all provinces of South Africa. In fact some Tillandsias such as T bergeri and T Houston need a cold snap to help induce flowering so the cold days may actually help you in spring.
The images in this post were all taken in the nursery today to illustrate that in a Tillandsia collection there is always something in bloom.
https://fcbs.org/articles/cold_sensitivity_of_bromeliads.htm