A grapefruit tree, like most citrus, is a tender tropical to subtropical plant. Hardy only in USDA planting zones 9 through 11, the grapefruit tree is slightly less cold-hardy than an orange tree. They come in many varieties, from white acidic flesh to yellow tart flesh and pink and red flesh that is much sweeter. These trees need little maintenance after the first year and do not need to be cross-pollinated with another grapefruit tree.
Choose a location in the landscape that has full sun and is high enough to drain off any excess water. The best time to plant grapefruit is spring; however, in warmer climates the tree can be planted any time.
Dig a hole twice the diameter of the root ball. The tree should sit at a depth slightly higher than it was in the growing container; make sure the graft union is above ground level. Create a small mound at the bottom of the planting hole.
Add compost to the dug-out soil only if the soil is heavy clay and does not drain well. Amendments are not needed if the soil drains well and will only create a less stable base for the tree.
Drape the roots over the mound in the hole, and set the tree so the main trunk is straight up. Place enough of the dug-out soil to cover half of the root ball and water to settle the soil around the roots.
Continue to fill in the hole until the soil is level with the surrounding ground. Water again until the soil is evenly moist down to the roots.
Bring in some extra soil to make a 6-inch-high by 6-inch-wide ring 12 inches from the trunk all the way around. This is called a watering ring and keeps the water directed toward the roots while they are getting established.
Water every third day for the first two weeks, then cut back to once a week for the next two months. Do this by filling the watering ring and allowing the water to slowly drain into the soil. The ring will slowly disappear, and at that point the roots should be established.
Pull all weeds from the soil in a 2-foot-wide ring around the tree. It is better to do this by hand, as a hoe may damage the roots. Mulch can cause the trunk to stay to wet and cause rot, so if you use mulch, place it at least 6 inches from the main trunk.
Apply a fertilizer made especially for citrus trees when you start to see new growth on the tree. Follow manufacturer's directions for application.