With their glossy leaves, fragrant flowers, and colorful fruits, citruses make elegant houseplants. They are easy to start too. Just plant fresh seeds of lemon, orange, or grapefruit in a mixture of equal parts of peat moss and perlite or coarse sand. Water well; cover the container with clear plastic and keep it warm (70°F). When the seeds germinate in 3 to 6 weeks, remove the plastic and place the container in bright light (but not direct sun). When the seedlings have several sets of leaves, transplant them to individual pots filled with potting soil.
Feed the plants with a dilute high potassium fertilizer every 2 to 4 weeks. Water moderately and keep in direct sunlight at least 4 hours a day. In winter, stop feeding, water sparingly, and keep the plants above 50°F
It may take 7 years or longer for a citrus plant started from seed to flower indoors, so you may want to buy a plant or propagate cuttings from one that is known to flower and fruit. To encourage fruiting, repot every spring in a pot one size larger and place the plant outdoors in summer. Prune leggy branches in early spring. The fruits, although often too tart to eat raw, make excellent marmalade.