The basis of the game is to grow overly large veg to win prizes. However it will need to be in top condition to win prizes rather than just size. To get top condition large veg, the player will have to learn about the veg, what soil they are best grown in, how much sun light, water etc. It will also provide information about the veg and how they are good for children. Like the myth of carrots help you see in the dark etc.
You are a chef in your own food bar. You have to produce foods for your customers want. Depending on what food you give and how you cook these foods (healthy or non) will effect your customers healthy. Constantly feeding them non healthy foods or using to much oil/fat will make them gain weight while healthy foods keep them healthy.
Making/using your garden to create animal and bug friendly environment by learning about the habitats of these creatures. (possibility of getting outside game interaction?) Matching the bug or animal to there habituate you will be able to make a home for these mini beasts. This could be by putting a bird feeder in a tree or making a rocky areas for creatures to crawl under. The more friendly your garden, the more wildlife comes into your garden.
How could this possibly get outside game interaction?
Rating their own garden on how much wild life is living in the garden
Tips on how to get more wild life in the garden
How to make homes/habitats for these garden critters