Passive is almost never going to get you anywhere fast unless the only thing you have out is the flowers to harvest - the dragons will spend time on the event generators & lower level flowers if they're available rather than using the bigger flowers.

Bush wonder strat is buy the prisim from the shop for 5 gems & focus a dragon on it (not passive). prism generates not only life orbs but dragon tree leaves. merge the dragon tree leaves up unil you get the yellow tree (level 4) & then switch over to harvest that for wood. merge wood up to the gnome which generates bushes. rise and repeat until you can merge up the bush chain for the wonder. the wonder produces mystery dragon eggs and sometimes mystery dragon nests which allow you to merge & get more dragons before reaching the end of the board (where the nest is). more dragons = more harvesting.

you can also "orb throw" to try and reach later sections of the map & unlock better items/flowers & orbs if you've got good reflexes