Smaller and quieter than the Christchurch botanical gardens. We went in December and the rose garden was in full bloom. It was gorgeous. You can also get food at the beautiful homestead restaurant on some days of the week. The homestead was closed on the day that we went so I would advise checking ahead of time on the website.
We were able to walk to and do both the Mona Vale Gardens and Christchurch Botanical Gardens in the same day.