It depends on how much you would like to see, but the main garden area is fairly concentrated. There are some trails that will require you to walk more if you choose to do so. All paths are either paved or gravel.
The main area with some exhibits, the little restaurant and garden exhibits is probably about 3/4- 1 mile total. I managed that fine - with some foot problems I was having. The hiking trials have much more walking - miles of walking through terrain that is up and down- so wear the correct footwear for that!
It all depends on you. It's a beautiful place and a nice place for a walk
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