We visited here almost by accident as we noticed them whilst driving past. There were several large car parks adjacent to them but we were not sure where to park as most of them were for students and staff at the university and needed permits to be displayed. We finally found some short term visitor parking and parked there, hoping this referred to the gardens as well as the university buildings. There was no charge for this or for the gardens themselves.
We enjoyed wandering around but do not feel it would have been worth a special visit unless you wanted to see trials of plants suitable for the area. Many of the people in the gardens seemed to be students with laptops or families having a picnic. I think it is a facility for the university rather than a public garden in the normal sense.