It does not allow balloons into the Arboretum, nor the Botanical Garden.
And good luck to him
Playing a song from a speaker is the only part that I'm unsure about. I would recommend calling in advance about that, but the proposal feel free.
WHAT DID SHE SAY?
They are recovering from the freeze and flood. Contact them directly
Please call the Mercer Arboretum main number for the last items you mentioned. There are many proposals which happen there, however adding a little more elaboration like balloons, flowers, and a singer may make things more complicated. It is a public space but there are limitations. It sounds like a very sweet occasion and he sounds like a good guy.
I dont see why not, people come here for photoshoots all the time and it's actually a beautiful background to the photos. Go for it and good luck!
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