Or how about setting a limit to the number of US participants? That was the big issue last project. We had plant candidats, but could not find them in large enough quantities! Sounds harsh to limit it, but all the trouble really took out some of the fun.
What I liked about chosing only one plant is that it sort of 'forced' people to grow a plant they otherwise would have never chosen. Royal, your idea of chosing a slate of plants is nice. That way we could have mini intermediate plants (as usual) as well as some larger intermediate plants for those who want bigger stuff. And it would be a nice change from the usual way of doing things.
Anyways, if you do this project before the end of summer, i'll be forced to sit this one out
. I will be pretty much internetless from end of next week to late august, since I'll be at my countryhouse in France most of the time, and then spending nearly 2 weeks in Spain.