Citrus trees can be one of the most rewarding fruit trees to own, typically producing a harvest full of vitamin C in the winter months. At the same time, citrus can be quite demanding, with trees preferring certain temperatures, acidity and sunlight, among other things. Still, if you take time to research your preferred citrus varieties and account for those needs, you may easily be able to produce an abundant crop year after year.
The first thing you will likely want to determine is your growing zone and your minimum low temperature each year. Citrus trees are not cold-tolerant, though some species are able to survive colder temperatures better than others, with little or no damage . Grapefruit trees and orange trees may be able to survive temperatures in the low 20's. Lemon trees and lime trees will be in danger in temperatures of below 30 degrees for prolonged periods of time.
The soil acidity often not only affects how much fruit you may get, but the quality of that fruit, as well. Typically, citrus prefers a soil pH between 5.5 and 6.5. To increase the soil acidity, lime is often used. Decreasing soil pH is often done with aluminum sulfate or sulfur. Follow package directions for these products and be sure not to use too much on a first application. It is always best to add more later.
Generally, citrus trees will need to be in a sunny location, though they can also thrive in partial shade. If you live in an area where the temperature could pose a threat to the tree, then putting it near a south facing wall is likely a good idea. This will provide the tree with some radiant warmth from the house, as well as give it the most sunlight possible in the winter months when the sun is lower on the southern horizon.
The spring is often the best time to plant a citrus tree, but given the warm conditions where it lives, any time of the year is acceptable. The planting hole should be approximately twice as large as the root ball or pot the tree comes in. Use peat moss and dirt to fill in, along with plenty of water to allow the soil to settle. If mulch is used, it should not touch the tree.
Citrus trees often do not need watered, except in periods of drought. To determine if water is needed, check the topsoil and see if it is dry to the touch. If it is, then watering would be appropriate. Fertilizer can also be used on citrus trees. A fertilizer designed for slow release and is 12-4-8 is recommended for most citrus varieties. Use approximately 1 pound of fertilizer for each year of the tree's age.