@shiftrox, I have an idea about the trees - what if the reward from the trees increases with their level? For example, level 1 - base reward, level 2 - base reward + 5%, ... level 4 - base reward + 20%. The percentage can be changed but the whole idea is that the bigger tree should bring a better reward than the young tree. We can use more worm/fertilizer to grow the trees faster and get a better reward in the future.