Although Citrus is a subtropical genus, northern gardeners can grow lemons, oranges, and other citrus trees in containers to enjoy fresh fruit. Standard-size orange and grapefruit trees can grow 18 to 22 feet tall, whereas dwarf varieties only grow 8 to 12 feet tall. Most citrus varieties are self-fertile, so only one tree is necessary. On average, fruit bearing begins when the trees are between 3 and 6 years old; however, exact timing will depend on the type of citrus (lemons, oranges, grapefruit, etc.), the cultivar, your climate, the health of the plant and its care, and other factors. Flowering is not seasonal, but occurs during warm weather and regular rainfall. Flowers and fruits may coincide.
- Citrus trees should be planted in a sunny and wind-protected area.
- In the citrus belt, trees can be planted at any time, however, spring is the best time for container grown plants.
- Standard-size trees should be spaced 12 to 25 feet apart and dwarf trees should be set 6 to 10 feet apart. The exact distance depends on the variety. The bigger the fruit, the farther the distance.
- If the soil is not well-drained, plant the trees on a slight mound to prevent waterlogging.
- To plant citrus trees inside from seeds, remove the seeds from the desired fruit. Soak the seeds overnight in water and plant them ½ inch deep in moist potting soil. Cover the pot with a plastic bag or wrap and let it sit in a warm and sunny spot for a few weeks until the seeds start to grow. Then, remove the plastic but keep the pot near a warm and sunny window.
- A few weeks after planting, and for the first few years (before bearing age), feed the tree a balanced (such as 6-6-6) fertilizer.
- For newly bearing trees, provide nutrients to continue branch and leaf growth but also to replace nutrients lost by fruit forming. A citrus blend is ideal.
- Check manufacturer’s directions, or ask a garden nursery, as to how often and how much to apply during each year of a tree's growth.
- Mulches are not recommended for citrus trees, but if trees are located in a cultivated plant bed where mulch is used, keep at least 12 inches of bare ground between the tree trunk and the mulch. Pre-emergent herbicides may be used to prevent weed seeds from germinating.
- Fruit thinning is unnecessary.
- Depending on the climate, fruits may take 6 to 8 months to ripen.
- The best indicator of ripeness is taste.
- Harvest the fruit by cutting them off with pruning shears or by pulling the fruit stalk from the tree.
- Undamaged fruit can be stored for several weeks at cool temperatures.