Again I didn't quite make it.
I followed the directions on the site and didn't see any such group in sight.
This may be due to the time I went by which was a little later in the day, 12ish, but I figured with lunch and all being eaten that someone would be there around lunch. There was also some kind of zoo walk or something going on and the traffic was terrible. The zoo parking itself filled up and they were turning cars away. Many other lots in the area were roped off.
Nest season I guess I'll just have to arrive earlier and beat whatever traffic comes up. I'll also have more plants to swap which I guess is a win-win situation.