Flowers

From Bunni Wiki

Posie Garden
As the cheapest food with medium regrowth rate, posie garden doesn't really satisfy the hunger of your creatures and could be considered ineffective.

Tulip Garden
A medium prized food, tulips garden have good regrowth rate and decent satisfaction for your creatures. Most of the time, tulip gardens are enough to feed the workers.

Rose Garden
Very expensive food with high satisfaction but with a slow regrowth rate. It works well when combined with a batch of effective workers like Pandas (on mills) and Monsters.

Note
Another source of food is the fruit from fruit trees.