The most important thing to take into consideration when growing a star fruit tree is climate. The star fruit is a subtropical plant that can be grown in USDA growing zones 8 through 11 but will need winter protection in zones 8-9. When grown in the right climate, your star fruit tree will provide attractive, delicious fruit and clusters of fragrant pink flowers that bloom throughout the year.
Remove a 10-foot-diameter circle of grass centered on the spot where you want to plant your star fruit tree. Uproot and discard any roots as well, or the grass will quickly grow back.
In the center of that circle, dig a hole that is roughly three times the diameter and three times the depth of your star fruit sapling's current container.
Mix half of the excavated soil with an equal amount of aged organic compost. Fill the hole in two-thirds of the way with the soil/compost mixture.
Plant the star fruit tree in the hole so that the top of its root ball sits at least 2 inches above the ground (you may have to fill in more soil/compost mixture to get it to the right height). Fill the hole with the soil/compost mixture and tamp the soil down firmly with your feet to remove any air pockets.
Spread a 4-inch layer of mulch around the star fruit tree, within the circle of excavated grass, but keep the mulch at least 1 foot away from the trunk of the star fruit sapling.