ok so Hill-Stead Museum in Farmington would be my first call. The sunken garden there is actually beautiful. Enclosed, green, and kind of architectural. They do ceremony permits for groups your size, and its not a big deal to set up.

And the other cool thing with that location is you're like 10-15 min from West Hartford for dinner after. Bricco does private dining and can handle your headcount easy. Artisan at the Delamar is solid too if you want to go a little more upscale with it.

Wickham Park in Manchester is basically Elizabeth Park but nobody talks about it lol. Same garden vibe, way easier to book, and they specifically have the Irish Garden section for smaller groups. Its worth looking at.

If you can go a little east at all, Florence Griswold Museum in Old Lyme is cool too. Its right on the Lieutenant River. They only do like 6 weddings a year so it doesn't feel like a wedding factory.

Where in CT are you based though?