myrianthus arboreus cold hardiness

[Nicola]

Hi there, I haven't been on the form for years!
We have a garden just North of Newcastle and the climate is classified as warm temperate but people are growing mangoes there.
I am interested in myrianthus arboreus because the leaves apparently can be used for soup. (and birds are only after the fruit)
How cold hardy is that tree?
Its available at daleys. atm.