Just saw your enquiry regarding growing olives in Ireland. Why not? You will
stand more chance of succeeding if you start with a mature tree[15 yrs or
so] if it is to be outdoors in winter. South facing wall would be
recommended. Where in Ireland are you and how much frost do you have? If
frost, you will need to wrap the trunk with agricultural fleece in winter to
prevent the frost cracking the bark. Here in Sussex we are presently
watching very small, immature olives[variety, pendolino] swell and hope
there will be enough sunshine to complete the ripening process. Good luck.
Edward Faridany