Just did my second lot of ten minutes unlimited energy.
I had 25 elm trees ready to go, and it took about 2 minutes to quick-collect from the lot.
I got 63 green worms, which is about 2.5 per tree.
I only need 14 more green worms for the rest of the challenge. Nice.
I also picked up 86 more blossoms and six more blue worms from skunks and six bonus blue fire things which mean I can do the trade.
I like these weekend challenges.