Usually planted as an annual. Like window box geranium (Pelargonium hortorum) actually a sub-shrubby perennial that would like to persist, may perhaps do so here for a time in a sheltered position on a mild site near salt water. A house near me sometimes has geraniums winter over in a planter built off the front of the house, where a roof overhang interferes with frost penetration.

i didn't see any survive this last winter, but i've seen them survive weather dipping into the low 20's high teens in a good spot.

there was one planted on the S side of an apartment building near the trader joes on 21st in NW portland. that one did really well for a while- urban heat island, protected from winds...

in one sense, i like plants like this. think of them as an expensive annual that MIGHT make it a few seasons. on the other hand, they can look pretty crappy and sad when the cold sets in.