Gardenscapes-The winning strategy for level 75 is to charge the Rainbow Blast as soon as possible and apply it to the berries. This way other pieces begin to fill the upper area of the field, and the acorns finally become available to collect in matches (you will also need to break the crates below first). With luck the Rainbow Blast can fall near the acorns, letting you achieve the goal of the level immediately.
Keep in mind that the Rainbow Blast power-up appears faster, if you blow up the bombs in combo explosions, not just one by one.