Citrus land and climate requirements
Setting up a citrus crop that will be profitable in the long term requires careful planning and the right site. The following information will help you determine if your property has the right land and climate for growing citrus.
Citrus trees require a minimum of 60 cm of well-drained topsoil; a depth of 1 m is preferable. Use an auger to check that there is no barrier to drainage within 1.5 m of the surface.
Loams and sandy loams are preferred. Very sandy soils require expert management as they have a low water-holding capacity and nutrients are readily leached. Wetter clay soils can cause collar and root rot and the risk of tree death. A soil pH between 6.0 and 6.5 is required. Avoid soils with a natural pH above 8.
Slopes of up to 15% are suitable provided the farm is designed to minimise soil erosion. Steeper slopes present a major erosion risk and make it difficult to operate machinery safely. Avoid these wherever possible.
Citrus will tolerate high temperatures provided the trees are well supplied with soil moisture. Trees are sensitive to frost, but this varies with variety, tree age and health.
A young tree or a tree with a recent growth flush will be damaged by even very light frosts. A mature tree that has hardened off may tolerate temperatures down to -5oC for a short time without being seriously affected. Leaf, branch and fruit damage can occur. Trees under any stress, such as trees with a crop, will suffer greater damage. When frost causes fruit drop before harvest, some fruit left on the tree may be damaged internally, but show no external symptoms.
Lemons (except the Meyer) are more sensitive to frost than oranges. Mandarins vary widely in their frost tolerance. In general, citrus is not recommended in areas where there are heavy regular frosts.
Some orchardists in frost-prone areas use wind machines to prevent frost damage. These expensive machines are reserved for high value mandarins (Murcott) or export oranges (late Valencia) that carry crops through the winter.
Exposed, windy sites should be avoided because of the risk of wind scarring of the fruit rind, which causes the fruit to be downgraded. Properly designed windbreaks are essential.
Drier coastal or inland areas are preferred for citrus to reduce the risk of pest and disease problems.
Irrigation is essential for regular cropping. In areas where rainfall is below 700 mm per year, 1 hectare of mature trees will need 8 to 9 megalitres of irrigation (1 megalitre (ML) = 1 million litres). Citrus trees are highly sensitive to salt. Avoid waters with an electrical conductivity above 1800 microSiemens per centimetre (µ/cm) or a chloride level above 450 parts per million.