Water the newly planted seed until the soil is moist but not soggy. Cover the pot loosely with plastic wrap to create a greenhouse effect to keep the seed warm and encourage growth.
Fill a 4-inch pot three-fourths full with a rich potting mix that drains well.
The grapefruit (Citrus paradisi) has come a long way. From its first recorded history in the West Indies during the mid 1700s to propagation in Texas’ Lower Rio Grande Valley during the early 1900s, the grapefruit has become a fruit that can stand alone or be used as an ingredient in the kitchen. Grapefruit can be grown at home from seeds and planted outdoors in U.S. Department of Agriculture plant hardiness zones 9 through 11. Although fruit production can be more limited than that of commercially grown trees, growing a grapefruit tree from seed should produce fruit.
A south-facing window covered with sheer curtains provides sufficient light without exposing the seedling to direct sunlight, which may burn the plant.
Place the covered pot in a brightly lit, warm location with a consistent temperature of around 70 degrees Fahrenheit. Monitor the progress of the plant, adding water as necessary to keep the soil moist. Watch for the seed to sprout and leaves to form.
Press one grapefruit seed into the center of the pot. Push the seed into the soil so it is twice as deep as the seed is long. For example, if the seed is 1/4 inch long, plant the seed 1/2 inch deep.
Transplant the seedling to larger pots, such as 6-, 8- and 12-inch containers, as it grows so the roots will have plenty of room.
How to Plant Grapefruit Seed
Under ideal conditions the grapefruit seedling may flower and produce fruit in six to seven years.
You can grow your own grapefruit tree from seed harvested from your breakfast fruit. Plant the seed and keep it warm so it germinates indoors.
Plastic or clay pots
Fill the pot to within a 1/2 inch of the top with sterile, soilless potting medium, or create your own by combining equal parts milled peat moss and half perlite or medium-grain sand. Saturate the mix with water and let the excess drain off for 15 minutes before sowing.
Repot the grapefruit seedlings in spring into a pot that is no more than 1 to 2 inches larger than the previous pot. Use soilless medium and a pot that has multiple drainage holes around the base.
Grapefruit seedlings with undesirable fruit can still be enjoyed for their highly fragrant, waxy white flowers.
Sow three grapefruit seeds in the pot. Sow the seeds at equal distance from one another at a depth equal to twice their length. For example, a 1/8-inch-long grapefruit seed should be sown at a depth of 1/4 inch, while a 1/4-inch-long seed should be sown 1/2 inch deep.
Lift the plastic wrap and water the grapefruit seeds whenever the soil feels dry on the surface. Add water slowly to avoid dislodging the seeds. Keep the soil moist in the top 1 inch or so. Put the plastic wrap back in place after watering.
Small plastic pot
Soilless growing medium
Wash a small plastic pot that has multiple drainage holes around the base. Size doesn’t matter, although smaller, 2- to 3-inch pots warm up more easily. Dry the inside with a clean cloth.
Grapefruit trees sprout easily from seeds, although the seedlings lack the same fruit quality as commercially grown trees.