From Hamilton, take York Blvd. towards Burlington and watch for the Arboretum signs. Turn on the Old Guelph Road, go under the 403 and up the hill and turn left into the Arboretum. There is a fee for entrance or parking if one is not a member of the RBG. Meet in the parking circle.
From Burlington, take Plains Road to the west past the RBG Headquarters. Go straight at the stoplights onto York Blvd at the point where Plains Road turns north to get to hwy 6. Watch for the Arboretum signs after you pass the Rock Garden. The Old Guelph Road goes right. See above for the rest of the directions.
From Dundas, follow York Road and then turn right at the stop at Old Guelph Road. Shortly after the railway crossing the entrance to the Arboretum is on your right.