The hardy cacti are starting to plump up after spending a winter looking like shrivelled up prunes. The key to success with the various types of hardy cacti is a very dry location. If the cacti are plump with water going into winter, then a hard frost will cause the water in the plant cells to freeze, and consequently expand and rupture. The strip against the west side of my house has very dry soil and receives little natural moisture or snow accumulation.
Among the cacti that have survived Niagara winters in my garden are various Opuntias, including Opuntia kleiniae (2nd picture) Echinocereus, the ball cactus (3rd picture) and the tall Cylindropuntia imbricata (5th picture)