Charlie Pridham wrote:

It is typically monocarpic and dies after flowering which normally takes two
years but can be 3 in colder parts. (try G palmatum its easier!)

I would have said the same Charlie, but I do know of a few that are
flowering for their second and third successive years - hence my
wavering towards 'short-lived perennial'.

I certainly agree that G. palmatum is by far the easier and if anything
more reliably perennial. I have one in flower for its 4th time,
although it is noticeably weaker this year and the exhaustion of seed
production may well see it off. It seeds itself about both in and
outside the garden - one day I'm half expecting to see a hybrid with
our native Herb Robert (G. robertianum).

These Atlantic island Geraniums are splendid plants and even if they do
keel over after flowering, or are a bit on the tender side (or rather a
lot in the case of G. maderense) they are well worth a bit of effort.
I just wish they didn't stink so much!