I found this game about 5 days ago and have to admit I am completely enthralled. Here's what I love about it - it's similar to the city building game feel that I love without the free form building portion that takes creativity that I don't have.
While I recognize that the developers want to make it challenging and encourage people to support the game I think there needs to be capitalization on the truly unique aspect of the garden. Obviously I enjoy the match 3 puzzles but if I wanted to play a match puzzle games there are tons of other options out there for free and without such restrictive limitations on how often you can play (i.e. Earning a life every 30 minutes) but I'm interested in the game because I want to see how the garden develops.
That being said, earning one star per level beat... it would literally take most players years to develop the garden and sorry but I feel most people won't stay invested if the game play is that slow. Which leads me to the suggestion... I know this is vague but please make it easier to earn stars!!! I don't have many ideas on how to implement that but if you could figure something out I think you'll actually retain players more easily and people will spend money on playing because they want to more easily that because the have to.