Citrus have always been popular. They are great tasting, vitamin rich, can be picked progressively over quite a long time and are relatively easy to grow. Early mandarins begin to ripen from early June with oranges, grapefruit and lemons holding on until January. This winter - early spring fruiting makes citrus so valuable when other fruit is more expensive. They are also very attractive trees with their glossy green leaves, fragrant blossom in spring and coloured fruit in winter.
Citrus will grow in warm or mild climate zones. Providing frosts are not severe they will tolerate cool conditions. They will thrive in hot inland conditions providing they have water. They require a sunny position protected from cold winds. Citrus prefer a sandy or loam soil. They will tolerate clay soils providing they are planted on a raised area with lots of compost mixed into the soil.
Refer to our blog What Makes a Good Soil
Citrus trees are available most of the year and can be planted anytime provided they are watered regularly in summer. The best selection is available in autumn, which is the best time to plant.
Citrus are big feeders. A moderately sized mature tree requires at least 500g of Tui Citrus Food, ican Fruit Food, or Novatec each year (organic gardeners should use Tui Organic Fertiliser). Two thirds of this should be applied in late winter and one third in January. Pelletised Sheep Manure is a useful alternative. Do not cultivate under citrus trees as their feeding roots are relatively close to the surface.
Citrus must be watered regularly through spring and summer. Irregular watering can cause fruit drop and fruit splitting, not to mention reduced yield and dry fruit.
A layer of mulch spread over the surface under citrus trees will conserve moisture and improve performance. Take care however, to keep mulch away from the base of the tree trunk to avoid collar rot.
Citrus trees can be attacked by white fly, scale insects, aphids, thrips, mealy bug and mites. The honeydew excreted by these pests then causes black sooty mould to build up on leaves and stems. Grosafe Enspray 99 oil applied every three months normally maintains satisfactory control. Increase the frequency if there is a build-up of insects. Verrucosis, a fungal disease which sometimes attacks lemons causing rough fruit, is controlled by spraying withGrosafe Free Flo Copper.
Whitefly can reproduce very quickly (they reproduce faster as temperatures rise in summer) so it is vital that you begin treatment at the first sign of them. Combine Enspray oil and Yates Mavrik and spray thoroughly, focussing on covering the underside of the leaves where they lay their eggs. Repeat after 10-14 days and a third time 10-14 days after that and ensure each time that you get complete coverage of the tree leaves. Especially the undersides. If you don't break the lifecycle, you won't get rid of the whiteflies.
If Ants are all over your citrus tree, the ants themselves aren't a problem you need to treat but you can be sure that there is another type of insect on your citrus tree. Ants eat the honeydew produced by Aphids, Scale insects, Whitefly etc so they will protect them, essentially 'farming' them! Get rid of the problem insects and the ants will go elsewhere to find food.
Citrus tend to be self-shaping and so need little pruning in that regard. Most varieties can become quite dense and benefit from some thinning out. The benefit of thinning out is to maintain good airflow and light through the tree. Good airflow helps to minimise fungal diseases and pest infection as the centre is no longer sheltered and warm inside. Lemon trees can sometimes require pruning back to make them more compact and easier to manage. An old wives tale for how much to thin out a citrus tree was that 'a bird should be able to fly through it'. You don't have to test that theory but it gives you an indication of how open it should ideally be.
Make sure that any shoots that emerge below the graft are removed. These are easily identified as they have different foliage.
Citrus will fruit on 1 year old wood and/or on new seasons growth.
Limes have become very popular in recent years, largely because of the interest in cooking created by the many cuisine programmes on TV, and in magazines.
Limes need protection from frost until established. They will not tolerate heavy frosts.
NZ navel oranges are rated very highly compared to imported oranges for flavour.
Very popular with families because they are great in school lunch boxes due to the easy peel nature of most varieties.
These are a very reliable cross between grapefruit and oranges, ripening Oct– Jan.
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