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How to Grow Citrus Trees : Citrus Secrets

8th October 2008



Citrus Secrets

Brighten up your winter garden with the brilliant neon colours of edible citrus fruits.

Have you ever considered growing citrus at home? Apart from being edible and rich in vitamin C, the lush, evergreen foliage of citrus plants, their scented blossoms and the brightly coloured fruit that appears in winter are valuable characteristics in any garden plant.

Gardeners in frost-free climates have long delighted in the decorative qualities citrus fruit brings to the garden, and admittedly citrus trees do grow best in warm, temperate and subtropical climates. However, they can also be grown in wind- and frost-free dry inland areas if watered regularly.

If your live in a region with mild winter frost (-1°C to -2°C) lemons, navel oranges, certain Valencia orange varieties, some naartjie varieties (satsumas), clementines and mandarin hybrids, limes and kumquats can be grown in the garden. Calamondins will tolerate brief spells of light frost. Alternatively, position other citrus in a warm micro-climate within the garden, such as against a north-facing or west-facing wall, or on a roofed patio. Even if your garden experiences moderate frost (-3°C to -5°C) you can still add a touch of the Mediterranean to your garden by growing kumquats, lemons and ‘Satsuma’ mandarin trees in the garden, provided that the fruit fully matures before the frosts of winter begin, as only dormant trees will survive heavy frost. Your local nursery will advise you which varieties to choose. Other citrus can be grown in containers which can be moved well under the roof of a north-facing veranda during the winter months to shelter them from frost. You can also protect the plants by covering them with winter fleece.

Homeowners with small gardens need not deprive themselves of home-grown citrus. Firstly, planting the larger-growing citrus trees in containers will limit their ultimate size. The plants will thrive in a container, as long as they receive enough sunlight and are protected from freezing winter weather. There are also dwarf citrus varieties which only grow to about 2m tall.

Success with citrus

To achieve the best growth and a bountiful harvest, bear in mind the following :

Plant in full sun in well-drained soil

The roots of citrus require more oxygen than many other trees so make sure that the soil drains well and is never waterlogged. The best soil for citrus is moderately heavy loam mixed with a good amount of decayed manure and sand. Heavy clay soils are not suitable. The soil in containers should be a fibrous loam enriched with dried cow manure and a tablespoon of bonemeal.

Water regularly

Citrus trees need regular watering particularly during the time they are flowering and setting fruit, when the soil should be kept moist at all times. For the rest of the year, make sure that the trees do not dry out completely. To conserve moisture, keep the root area well mulched at all times, preferably with compost.

Fertilise Citrus trees correctly

Apply a balanced fertiliser that has a high nitrogen and medium potassium level in July, December and March. During the first few years of growth, give the tree 300g at each application. In subsequent years gradually increase this amount to 2,5kg for a mature, large citrus tree. In addition, give the tree 75g of Epsom salts (magnesium sulphate) three times a year. First put down a mulch of compost and then spread the fertiliser around the trunk, going as far out as the drip line of the branches. Water well after application.

Pruning Citrus Trees when necessary

In recent years it has been proved that pruning citrus can be beneficial for fruit production when it is done in such a way as to let more light penetrate the canopy of the tree. Always prune after fruiting, and carry out many smaller branch prunings, rather than removing just a few larger branches. Aim to have four to six well-positioned, scaffold branches by the first year of bearing. (Scaffold branches are branches that grow laterally from a tree trunk and that provide the framework of the mature tree). In subsequent years, remove ‘extra’ scaffold branches and thorny water shoots, as well as any suckers.

Protecting Citrus Trees from pests

Keep your citrus safe from pests, the most common of which is citrus psylla. An infestation results in a swelling on the upper leaf caused by insects underneath the leaf. Citrus psylla affects mainly young trees. Spray with Biogrow’s eco-friendly Pyrol or Bioneem, or Efekto’s Natural Insecticide.

Less common are the orange dog caterpillar, which can be removed by hand, or spray them with Pyrol or Bioneem, and red and brown scale which can be sprayed with Pyrol, Oleum or Dursban 2E.

Citrus Tree favorites

Grapefruit: These trees bear the largest of all the citrus fruits and are best grown in large gardens. Grapefruit thrive in frost-free areas and the fruits develop best in subtropical regions. Height: 3-6m, spread: 3m.

Tangelos:
These hybrids between grapefruits and mandarins bear the next largest fruit. They are yellow-skinned, large, juicy and thin-skinned. For maximum flavour, allow them to ripen fully. Height: 4,5m, spread: 3,5m.

Oranges:
The sweet orange tree varies in habit according to the variety. The size of the fruit also varies, with navel orange varieties generally being larger and sweeter than Valencia varieties. The time of ripening depends upon the locality. Early ripening navels include ‘Newhall’ and ‘Palmer’ which ripen in May and June, and ‘Bahianinha’ which ripens from April to June.
Height: 5m, spread: 3-5m.

Mandarin oranges:
Grown where temperatures will not drop below 5°C. The fruits have loose rinds. Height: 3-4,5m, spread: 4,5m.

Lemons:
Lemons bear fruit throughout the year in many parts of South Africa. Although frost tolerant, the trees may be damaged if the temperature drops to -7°C at night. They grow well in containers. Smooth-skinned ‘Eureka’ is a popular variety. ‘Meyer’ is a slightly sweeter hybrid with a naturally compact growth habit. The Cape or rough skinned lemon bears thorns. Height: 3m, spread: 2-3m.

Naartjies:
A new generation of easy-peelers have been developed by citrus breeders. The best varieties to grow are Clementines and Satsumas. Best harvest occurs where temperatures do not drop below 5°C. Height: 3-4,5m, spread: 4,5m.

Limes:
Lime trees bear highly flavoured, acid fruits, and grow best in tropical climates. Varieties available include ‘West Indian’, ‘Mexican’ and ‘Key Lime’ and the seedless ‘Persian’, ‘Tahiti’ and ‘Bears Lime’. Plant them only in frost-free areas. Height: 2-4m, spread: 2-3m.

Calamondins:
These small citrus plants are a cross between a naartjie and a kumquat. They thrive in warm conditions, but tolerate brief spells of light frost. They make superb container plants. The miniature fruit has a distinctive flavour and ripens throughout the year. Height: 0,6-1,2m, spread: 60cm.

Kumquats:
These citrus trees fruit best in areas with hot summers and frost-free winters. They bear small orange-like fruits, 25mm in diameter. They are highly decorative as they bear their flowers and fruit for a long period of time. Height: 2m, spread: 2m.

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