One of the most attractive ways to display the evergreen foliage, fragrant blossoms and showy fruit of citrus trees is in containers. Dwarf or semi-dwarf varieties are best for containers, providing the same full-size fruit and lush, green foliage of standard-size citrus trees. The fruit of most citrus trees can be left on the tree for weeks, adding a colorful accent to your patio or garden.
The mobility of containers allows you to move your trees whenever you choose--perhaps for a special occasion, or to move the tree to center stage when it is loaded with colorful fruit or fragrant flowers. Choose a container slightly larger than the container the tree was in when you bought it.
Clay pots, wooden containers, even wine or whiskey barrels make good containers for citrus trees--just make sure they have drainage holes in the bottom. For added color, plant cascading flowers at the base, such as ivy geraniums, petunias, pansies, lobelia or alyssum.
To avoid the possibility of your citrus tree quickly outgrowing its container, choose a dwarf or semi-dwarf tree. These are citrus trees which have been grown onto under stocks (the bottom half) of natural genetic dwarf citrus trees.
Variation in Cold Tolerance
According to Don Durling of Durling Nursery in Fallbrook, an authority on the growing of top-quality container citrus, a true dwarf citrus tree grows up to 6 to 8 feet, a 75% reduction from full-size citrus. A semi-dwarf citrus grows to a maximum of 9 to 14 feet, a reduction of about 50%. Semi-dwarfs are the most commonly found and are plenty dwarf enough for containers.
When deciding what type of citrus to buy, keep in mind that although all citrus are susceptible to frost damage when temperatures fall much below freezing, there is significant variation in cold tolerance among different citrus varieties. While limes require an almost frost-less climate, the kumquat has been known to tolerate temperatures as low as 15 degrees Fahrenheit.
In addition to individual cold hardiness, another consideration when selecting a citrus variety is the fact that a certain amount of heat is required to ripen citrus fruit. Some varieties need more heat than others to ripen and become sweet.
If you live in a cool coastal area it will take much longer for your citrus to ripen than if you live in a hot inland area, and the fruit may not be as sweet. Valencia oranges need less heat to ripen than do navel oranges. Grapefruit has a high heat requirement and is best grown in the low desert or hot inland areas. It is sometimes tricky to tell when citrus fruit is ripe. Fruit color is often not an adequate indicator of ripeness--the only sure way to determine ripeness is to taste the fruit.
Low Heat Requirements
Lemons and limes are acid fruits with low heat requirements (they don't need to sweeten up), and are ideal for coastal areas. The Meyer lemon is a wonderful variety, as hardy as an orange, with large, ever-bearing fruit. It is a natural genetic dwarf, as is the kumquat, and naturally remains small. The Mexican lime, your standard bartender's lime, is your best choice if you live near the coast. Another exceptional lime is Bearss Seedless, which is light-yellow when ripe and almost as large as a lemon.
Whether in a container or in the ground, citrus trees need little pruning--prune only to shape or to reduce the height slightly. Dead branches and suckers arising from below the graft line should be removed. If you are pruning to remove shoots or branches damaged by frost, wait until new growth clearly defines the damaged areas.
Citrus trees in containers need to be watered more frequently than those in the ground. When you do water, make sure you water thoroughly, until water runs out the bottom of the container. Depending on the weather, you will probably need to water your tree once or twice a week. If it is very hot or windy you may need to water more often.
Container-grown citrus should be fertilized regularly with a complete fertilizer made especially for citrus. Follow label recommendations regarding container citrus. If chlorosis (yellowing) is not corrected by the usual applications of nitrogen fertilizer, suspect a micronutrient deficiency. To correct, apply a fertilizer containing chelated forms of iron, zinc and manganese.
Citrus can usually be grown successfully by the home gardener without a regular pest control program. You really don't need to spray unless the infestation is severe or the fruit is being affected.
Many pests are controlled naturally by beneficial insects that feed on the damaging ones. Aphids, mealybug and scale can be controlled with insecticidal soap or Malathion. An occasional shower with the hose helps to control mites--or spray with Volck oil or a miticide.