Puyas' native habitat is in the Andes in Peru, Chile and Bolivia. They normally grow in full sun, and are subjected to relatively harsh conditions not normally tolerated by members of the Bromeliacae.
Last winter, I subjected all of my seedling Puyas to the elements, to see which species are the most cold tolerant. Included were Puya Berteroniana, Puya Venusta, Puya Chilensis (chagual), and Puya Mirabilis. The were already established in 4" pots, and placed together in the open.
The lowest recorded temperature in Bakersfield was 28.5 degrees Fahrenheit. It was also one of the wettest Decembers on record. Because of the excessive rainfall, we had fewer days under 30 degrees than normal.
The toughest of all the plants was undoubtedly Puya Berteroniana. It came through with no discoloration on it's silvery armored leaves. It also tolerates full sun during the hot Bakersfield summers, with enough moisture.
The other species to survive was Puya Mirabilis, although it sustained some freeze- induced brown discoloration. It immediately started new growth in late February, with flowering occurring in early June.
Puya Chilensis and Puya Venusta all died as soon as it froze. This winter I plan to put some of them in a protected area to check for hardiness.