Leif Ericson Park & Rose Garden
http://www.d.umn.edu/~hawk0160/5230/glocal/index.htm

https://www.facebook.com/pages/Edelweiss-Nursery/112588937022

http://www.engertowerduluth.com/

http://www.duluthmn.gov/parks/parks-history/seven-bridges-road/

http://en.wikipedia.org/wiki/Minnesota_Point

Minnesota Point is over the lift bridge. The drive to the end has many cute residential gardens. I like to park at Sky Harbor airport and then take the path behind the airport between the beach and a pine grove. Threre are many native plants (including poison ivy, so beware).

I suppose I should also say, that 7-Bridges Road is not a formal garden but a drive with many pretty little bridges along it. You can park and walk along the trails. I particularly like the Amity Creek Trail. I have found that I like the natural woodland flowers rather than the more formal plantings. Depending on the timing of your visit, you will see lupines, wild phlox, wild roses and all kinds of things I cannot remember the name of right now. I hope you enjoy your visit.

Glensheen mansion grounds. 3300 London Road.

Here is a link that might be useful: Glensheen

I second bloom's suggestion of Glensheen. The gardens there are stunning, and they just added the new gardens and trails tour last year. You can pre purchase tickets online or buy them there - same day sales are in person only.