Crossbreeding is a feature that allow players to create a variety of items by combining 2 different seeds. To crossbreed, players will have to plant a tree first. While the tree is growing, players can see a grid over the tree if the selected seed in the player's Quick Slot is able to crossbreed with the tree. Simply tapping the tree with the selected seed will result in crossbreeding and a whole new tree with different a different item is created.
However, not every seed can be crossbred. For example, a Rock Pillar is at its final form and cannot be used to crossbreed with another seed to create new items.