Citrus fruits grow best between a temperature range of 130C to 370C. Temperatures below –40C are harmful for the young plants. Soil temperature around 250C seems to be optimum for root growth. High humidity favours spread of many diseases.
Citrus plants are grown in a wide range of soils ranging from sandy loam or alluvial soils to clay loam or deep clay loam or lateritic/acidic, provided they are well drained.
Fertile, well-aerated soils with a pH of between 6 and 6,5 are ideal. The growth, development and production of a plant depend on the physical characteristics of the soil such as drainage, density, texture, water-holding capacity, structure, soil depth, the homogeneity of the profile, erodibility, and the degree to which water can infiltrate the soil.
Citrus are best planted either in autumn or late winter after the risk of frost has passed. Autumn planted trees will need protection from frost. Planting holes of 0,5 x 0,5 x 0,5 m are prepared and the soil mixed well with 2 spadefuls of compost or kraal manure and 250 g of superphosphate. Once the tree has been planted, the soil must be firmly tramped down. As citrus roots are lacking in fine root hairs, humus should be added for soil improvement.
Since soil acts as the reservoir of water and since the water holding capacity differs considerably among different soil types, the irrigation requirement also varies greatly from place to place. During the first 6 months the trees should be irrigated twice a week and thereafter every 7 days.
During the first year, nitrogen may be applied every 2 months. From the second year, nitrogen must be applied twice a year, half in July and half in March. Fertilizer to be spread in a broad ring around the tree extending 50 cm beyond the canopy. Keep the fertilizer 10 cm away from the trunk. Fertilizer may also be applied through the irrigation system (fertigation).
Cultivation of citrus
