I would use about 2 hours. Depend on how much you want to see. There are some distance between houses, + a shop and a museum to visit.
Another option would be to plan a couple of hours on one day knowing that you can only see a portion of everything....for instance, just the Homestead that day. Then plan another day to see the Arboretum and some of the trails.
Agreed - 4-6 hours if you want to really explore a little bit of everything.
4 to 6 hours.
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