Jim O.
Google
Best gardens I've seen, there are many surprises around each pathway. It's a relatively compact botanical garden, not long walks on a big estate, but its packed with unusual trees and shrubs as well as some sculptures.
There is an outdoor museum of ships mast head figures from mainly wrecks around the Scilly Isles.
The gardens are over a mile from New Grimsby Quay, so may be a struggle for the less able.
There may be a minibus you can book or a golf buggy to rent, but I saw no details of where.