Instructions
Open your in-game encyclopedia any time a new Pinata appears outside your garden. When you first see the Pinata, the encyclopedia lists the requirements you must meet in order to get the Pinata to enter and live in the garden. You'll get gardener points when the Pinata enters the garden and when it decides to move in permanently.
Plant every seed that's available to you. You get a large gardener point bonus for growing a new plant. If you fertilize the plant, you can get up to three more bonuses. Each plant responds to a different color of fertilizer, and every plant species and fertilizer type is available at the shop.
Go to Gretchen's shop if you are low on points and can't find any new Pinatas. Gretchen sells tame, domestic Pinatas like Cluckles and BarkBark. Buy a pair of the same Pinata type and breed them. Once you get the gardener points for breeding them, sell the parents and their offspring for extra cash.
Give your Pinatas different items, like seeds or flowers. Each Pinata has a variant type, and when you feed it a certain food, it changes colors. Creating a different-colored Pinata earns you gardener points. Generally, a Pinata changes its color based on the color of the food it's given. For example, a buttercup would turn a Pinata yellow.