These flowers are not so instant as you design each and every one of them yourself.
I would suggest ages 4 and up. I spent at least 1/2 an hour playing with it myself this morning.
Not only gives lessons in colour and design but in physics as well. For example, try growing the centre of the flower to it's biggest possible size and you will see the petals on your flower spread apart... or come closer together as you shrink the centre of the flower.
Extra discussion about the game could involve scientific names of the parts of a flower, like the pistil, etc.
Maybe even add on a kitchen experiment...
Prairie Frontier - Anatomy of a Flower
How To Grow A Flower
Growing Plants Unit