I can't write a 100% way to get this achievement except give some helpful hints on how I got it. I'll list in matter of importance.
LEVELS
Knowing which level you are about to reach helps a lot. In the later level rock blocks come into the game and helped erase some flowers that I had no idea where to place at the end of the level previous. Here will be a description of the rock blocks to help place those useless flowers at the end.
Level 13 a single rock will be in the middle of the stage so you can erase one flower.
Level 15 rocks in the shape of a "+ " will be placed so you can erase four flowers.
Level 17 rocks will be added to the " + " corners making a square. So you can remove four more flowers.
Level 19 four rocks will be placed in the middle of each side on the square making a large diamond erasing four flowers from the board.
This is a nice picture made by LeiChat to show which level the block appears and how it looks.
http://leichat.files.wordpress.com/2011/06/flowerzgreen....gifSPADES
1.) Use the spade to place flowers in position to remove 4 or more flowers. If not capable of removing abundance of flowers go to 2.
2.) Use spade to remove the populous flower on the board At sometimes I had an abundance of particular color and used them to remove as many as possible. If no match for color go to 3.
3.) Use spades to move flowers into prime positions for later on.
BUTTERFLIES
1.) Use butterfly to create a sequence of 3 or more flowers.
2.) Use butterfly to make a match of two flowers for later use.
3.) Use butterfly on a multicolored flower if other two don't apply so the flower is erased from the board entirely when you finally match it up.
That's it hopefully something here helps.