Propagation
Cuttings taken during the growing period and may be grafted onto a rootstock. 

Botanic information
Leaf: The yellow-green leaves are ovate to elliptical with undulating margins and prominent winged petioles. The texture is leathery and the apex is acute.

Flower: The small white cyathiform flowers are arranged in a cluster and the flowering period is during late spring but may vary in tropical regions.

Fruit: The large yellow-orange berries are arranged in clusters. The skin has many small oil glands and the centre is pulpy with 11 to 14 segments. The small seeds are viable but the plant is commonly reproduced vegetatively.

Culture
Climate
Citrus prefers a warm climate with mild winters and grows well in a hot dry climate if adequately watered. Mature trees may also tolerate cooler areas and even some frost when they are dormant. 
Frost will damage any new growth and if the soil is too cold the tree will suffer a nitrogen deficiency causing the leaves to become yellowish.

Aspect
Citrus prefer a north facing sunny position that is protected from strong winds. They will tolerate some shade but must have half a day of direct light to be successful.

Soil
A sandy loam soil type is best suited and it may be slightly acid to alkaline with a low salt content. They dislike clay or clay based soil types, which are not well drained, so these soils need to be improved by adding sand and organic matter. 

To improve the drainage the plants may be planted in raised beds. Some species are grafted on to rootstocks that are root rot resistant and tolerates wet soils.

Planting
Planting normally occurs during early autumn or early spring and a one-year-old plant from budding. When buying the plant check that the plant has not been in the pot too long and become root bound as these trees are poor growers. 

Prepare a shallow hole that is one third bigger than the pot, then tip the pot on its side and remove or cut plastic bag then fold it down over the root ball. 

Tease any root bound roots out and place the plant in the hole never covering the union bud with soil and maintained the same level as it was in the pot. Fill in around the root ball with friable moist soil and firmly press it in. Thoroughly water the plant in but do not over water, a new plant once a week is sufficient.

Fertilising
When the plant is young do not use powdered fertiliser for the first five to six weeks. Apply slow release fertiliser or blood and bone and water in well. 

Liquid fertiliser may be applied every two to three weeks during the growing period and is placed at the drip line of the tree not at the trunk. 

When feeding during winter to early spring use a pre-mixed citrus fertiliser containing 10% nitrogen and water well before and after fertilising.

Pruning
Citrus trees have a compact habit and require little pruning. Oranges and grapefruit trees should not be thinned out but the other citrus trees may tolerate a thinning of the branches. 

If cut back hard it may take up to two years to recover and remove any shoots that appear below the grafted union.

Pests and Diseases
Fruit drop is common in citrus trees as the flowers produce excess and shed the unwanted. It is also caused by irregular watering and fertilising.

Young fruit may also drop as a result of citrus scab; citrus bug and bronze orange bug or the lack of copper in the soil. 
Phytophthora, sooty mould and collar rot occurs in wet soils or from over watering.

There are many insects that affect the fruit, leaves and bark of citrus trees; examples are orange fruit borer, spined citrus bug, white louse scale, citrus katydid, fruit flies, fuller’s rose weevil and mealybugs.

The leaves are damaged by citrus blast, crusader bug; wind Injury, citrus Leafminer, white flies, soft brown scale and the caterpillars of the small and large citrus butterfly. Stems may have swellings from the citrus gall wasp or the roots and branches are damaged by the fruit tree root weevil and longicorns. 

There is also a variety of mites and scales that damage the trees and if the trees are grown under glass red spider mite and white wax scale may become a problem.