Many types of citrus trees are easy to start from seed. Of course, you won't be able to propagate seedless varieties such as naval oranges and Bearss seedless limes using this method. However, Meyer and Eureka lemons,Valencia oranges, grapefruit, other limes, and other open pollinated or heirloom varieties of citrus work very well. A citrus tree you start from seed will take longer to bear fruit than a tree you purchase at your nursery. But if you want to save a few dollars and learn how people used to propagate plants they valued, starting citrus from seed can be a good exercise, especially for children.
Allow one or more fruits to remain on the tree longer than you would if you were planning to eat it, but don't let them start to decay because the seeds inside can begin to sprout and will sometimes rot. Pick a plump fruit, cut it in two, scoop out the seeds and rinse them with clear water.
Place seeds on an old window screen and prop it up in a warm, dry, dark, well-ventilated area for one to two weeks, until seeds are dry.
Mix 1/2 cup of moist peat moss, vermiculite and sand with 1 quart of standard potting soil and fill small nursery pots or flats with your mixture. Plant the seeds 1/2 inch deep and about 1 inch apart. Cover your pots or flat(s) with clear plastic wrap and poke a few small holes in it for air circulation.
Place your pots or flat(s) in an area that receives direct sunlight and where the temperature will remain around 70 degrees Fahrenheit. Water them every day until you see green sprouts emerging from the soil. Immediately remove the plastic wrap when this occurs (usually two to three weeks after planting).
Transplant seedlings to individual pots when they are they are 2 to 3 inches tall. One-gallon black nursery pots are recommended. Use a standard potting soil, keep them in a warm, sunny area, and water them once every week.
Give your young plants a balanced fertilizer when they are about three months old and repeat this application every month. Fertilize your citrus according to the instructions on your plant food label.
Transplant young citrus trees to their permanent outdoor location when they are 1 foot tall or taller. This can take one year or longer. Be sure to wait until after your final spring frost before you plant them outdoors.