Around ten years

there are examples at Wakehurst Place that have been there for at least 25 years.

an eldery neighbour had one for about 30 yrs.

They can live longer and average age is 10 - 12 years...

bit like us with an average life expectancy then mg:o)

Yup SBG... we have some in garden that are older. But, ours start to look sad and scruffy around the 10 - 12 year mark. Himself takes cuttings every year.