The best use of energy is chopping rocks rather than collecting from chickens and acers. The adventure will most often give you the yellow, red and orange stones and occasionally a green or violet stone. Rocks also spawned many skunks for me which gave me plenty of blue stones. I ended the quest with many extra red, yellow and oranges. Those who have the castle will also get many of the common colors as well as occasional violet and green stones. The garden looks very nice once it's complete. The final piece (I think it's the north) drops more coins as well as enchanters essence so far. It has a 2 hr. timer.
Good luck!
I went back to verify the timers and drops.
The west has a 15 min. timer and drops 100 coins.
The south has a 30 min. timer and drops 500 coins and simple glue.
The east has a 1 hr. timer and drops 750 coins and enchanters essence or glimmerdust (so far).
The north has a 2 hr. timer and drops either enchanters essence, glimmerdust or earth wisps.
So the garden as a whole can generate almost 5,000 coins every 2 hrs. I can't think of any building that generates that many coins in 2 hrs. So completing this event should help us build our coins back up eventually that the Celestial Storm event is depleting.