Look it up in Iron Knuckle's walkthrough.

You cannot get past the platforms yet or get bubble barries. Insted, go tow areas right from the entrence to flower feilds (Where you get the magic been) and hit the only tree in that area with your hammer, it will drop tow red barries. Next, give one of the barries to the red flower gaurd and she will let you through the gate. Go to the end of the road, talk to the flower there, and find a tree that has yellow barries and give it to the yellow gaurd, go to the end of the road, talk to the flower there, find the blue barry, give it to the blue flower gaurd and go to the end of the road and talk to the flower there.

The Bubble Berry is on the way to Lilly. You'll see an empty area, but there are Sushie platforms. You'll have to use those to access the Bubble Berry tree.

When flower field has the water back some area has sushie platform and use sushie's abillity to the tree and HAMMER TIME and it will fart a bubble berry out