Citrus really are a great ‘all-rounder’ in the garden. They have attractive shiny, dark green foliage, deliciously sweetly scented and beautiful white flowers, and they also produce fantastic fruit.
Citrus trees are budded or grafted plants, and their size is determined by the rootstock, soils and climate. To get the most out of your space, you can use close planting where the trees are planted 2 metres apart, as long as you keep each tree pruned and shaped so they still get light.
They are usually slow growing and have a shallow root system. As the fruit ripens slowly on the tree, it can be left and harvested as required. They are easy to grow as long as they are in full sun, have well drained soils, regular feeding, and are given plenty of water over the warmer months. If you’re planting them in a pot, as always, use a good quality potting mix.
Citrus are hardy, but when they are not happy, they don’t look good and fruit poorly. Talk back radio gardening programs would have noticeably fewer callers if not for the challenges caused by wide climatic conditions for this iconic backyard fruit tree.
First off, it is important to understand the basic requirements of citrus trees. They must be grown in full sun (at least five to six hours sun a day) in well-drained soil. If your soil is too heavy, it can be beneficial to make a raised mound and plant your tree in it. If your tree has started to suffer since the winter has arrived there can be several causes. One is that it has poor drainage in which case look at what you can do to drain water away from the tree and improve its situation and soil aeration.
Like many other trees which fruit abundantly, they require good feeding so choose a balanced organic based citrus food and give them a little bit monthly, rather than just a heap once or twice a year. Citrus trees often get specific leaf discolorations related to nutrient deficiencies, such as a lack of Zinc, Manganese, Magnesium, or Iron, so treat with the specific nutrient chelate to correct it.
It is also important to understand how citrus trees fruit to understand how and when and why they need shaping and pruning. Although most people never bother to train or prune citrus trees, early training and maintenance pruning will result in more reliable, high-quality crops on a more compact tree. The way that the trees grow, they produce most of their fruit in the outer 90cm of the tree canopy, so it is best to maintain a tree with a canopy of only 2-3 metres across. The bigger the tree is, does not necessarily mean that you will get any more fruit. For young trees it is best to tip-prune long growth shoots regularly to keep them compact and develop a good shape. Any vigorous shoots can be reduced to size in late winter. On established trees pruning and shaping is best done after harvest in spring.
If you have an old tree that is losing vigor, it can be rejuvenated by pruning it to reshape the tree after harvest or in late winter. Remove dead wood, crisscrossing branches and spindly growth. This opens up the tree and encourages a good air flow and allows sunlight to penetrate through to the lower branches. Trees over 25 or 30 years are sometimes pruned severely to ‘skeletonise’ them. The trunk and main branches are then painted with cheap white, water-based house paint to prevent the wood getting sunburnt before the new growth appears.
The main pests and diseases that they are prone to are scales resulting in black fungal, sooty mould. Citrus leaf miner and citrus gall wasp. The first two are readily controlled with a horticultural oil which is of low toxicity to you or the environment. For scale, it is also necessary to stop the movement of ants up the trunk to feed on the exudate or sweet honey dew that the scale produces. Citrus Gall wasp requires more diligent management. Prune off the galls as you find them.
Finally, when you add citrus to your garden, only plant into warm soil. In southern areas of Australia this may not be till late spring and may only go till late summer. Planting into cold soil will set your tree back and it can take years to recover.
At Sophie’s Patch the biggest challenges citrus face are our salty bore water which causes nutritional deficiencies and our wet winters which can cause the soil to become waterlogged. We live in an area called Mt Barker Springs and in winter the soil can get very wet. We did raise the level of the beds where they are growing to allow for this,. but I did not account for the soil slumping. Really I should have let the soil settle for a year before planting, but of course I was impatient and couldn’t wait any longer. so some have died in wet years and others are simply showing yellow nutrient deficient leaves. Lesson learned!? In the next newsletter I shall write about how gardening teaches us patience….. and how I am a slow learner!?
Seasons of Citrus (based on Adelaide’s growing conditions)
These essential citrus fruit most of the year round. The three main varieties are Lisbon which is thorny, Eureka which is similar but not thorny, and Meyer hybrid is orange-yellow in skin colour, and has a milder, less acidic fruit.
With oranges it is possible to have fresh fruit for five to six months of the year by choosing a couple of varieties. As a general guide, Washington navel oranges are loved for eating fresh, fruiting from May to September while Lane’s Late Washington Navel fruit from September to December. Valencias are loved for juicing and fruit from September – December.
Limes are very popular for those who like Asian cooking and anyone who likes a splash of lime in their gin and tonic. Tahitian lime fruits from June to October while the West Indian lime needs to be in a warmer climate and may possibly provide fruit for most of the year.
Mandarins are another citrus that can provide fruit for six months if you choose a range of varieties. The Imperial and Satsuma (often sold as Japanese seedless) fruit from April to June, while Emperor fruits in July, Murcott in August and September, and finally Kara in October. Closer planting again allows you to fit more into a limited space, and with three to four varieties, you will have delicious fresh fruit from April till September. Plant the mandarins 2 metres apart and the close planting will reduce tree size to around 2metres high. These smaller trees are still capable of producing up to 200 fruit per season.
Other citrus to consider include grapefruit fruiting from July to September and cumquats producing fruit year-round. Tangelos are a cross between a mandarin and a grapefruit and fruit from June to November. Although less commonly grown, tangelos have the flavour of a mandarin with a hint of grapefruit. However, they are not as easy to peel as a mandarin. The variety Orlando is the earliest fruiting in June, while Minneola fruits from July to September, and Seminole fruits from September to November.
Whatever combination you decide, there will be endless satisfaction from the multitude of flavours.