Without pruning or training, citrus trees grow naturally into bushy trees and will initially crop well. However, trees will eventually become overgrown with high proportion of dense, unproductive and spent wood. If trained, shaped and pruned in a specific way, trees will be healthier, easier to manage and will crop more reliably.
See my general guide to fruit tree pruning for information on pruning tools, pruning cuts and other general pruning information.
Citrus trees are tip-bearers. That is they blossom and produce fruit on the tips of branches. The most productive growth and fruiting occurs, in the outer 90cm of the tree canopy. So the optimum tree canopy size is no more than 2 to 3 metres. A large sprawling canopy takes up a lot of space and produces no more fruit than a compact well-managed one.
The number of terminal (tip end) shoots, determine fruit quantity. More shoot tips results in more fruit. Regulating the number of shoot terminals is the best way to achieve a balance between foliar growth and fruit numbers.
Shaping young citrus trees
Retain three to four main branches 50 to 70 cm above ground level. As the young tree grows, tip prune young shoots to keep the tree compact. The ideal shape is an upright tapering cone. Maintain this shape by tipping shoots and cutting back over vigorous water shoots in late winter. Early and continuous shaping minimises heavy cutting later on.
Maintaining the citrus tree shape
Citrus trees respond well to shaping. I usually prune them with hedge clippers. Trim any untidy growth to maintain the desired shape. The best time to prune citrus trees in Melbourne is after harvest in spring. Early pruning promotes early summer growth, that will mature before the summer heat and the arrival of pests such as leaf miner.
Reworking overgrown citrus trees
Older, overgrown citrus trees can be reworked to the desired shape using secateurs, hedge clippers or a chainsaw.
Very old (over 25 to 30 years), weak or disease affected trees may be cut back to induce further fruiting. However, old trees like this are at the end of their productive life and are often better off removed or replaced.
Be warned, if you severely cut back a citrus tree it will respond with vigorous growth. The long, whippy growth produced after a heavy prune is called watershoots. To avoid future issues you will need to regularly tip prune the resulting flush of growth. Once regrowth has reached around 40 to 50 cm you should tip prune it. Allow a further amount of regrowth and tip prune again. This encourages branching. Continue to tip prune until the tree has reached the desired size and shape.
Citrus tree espaliers
Citrus trees can be trained into an espalier. Citrus trees are tip bearers. Therefore, they are best suited to an informal green wall espalier shape. See my guide to fruit tree espaliers for more information on this.
Want to know more about Growing Citrus in Melbourne?
This is Part 4 of a 5 part guide to growing citrus in Melbourne. The links below will take you to the other four parts of my Melbourne citrus growing guide.
My citrus growing guides are based on my own experience, as well as the following books. They are all invaluable resources for the home gardener based in Melbourne. I strongly recommend you have a read of them, if you want to know more about growing citrus in Melbourne:
Ian Tolley: Commonsense Citrus, 2017
Bruce Mophett & Ian Tolley: Citrus, A Gardener’s Guide, 2009.
Louis Glowinski: The Complete Book of Fruit Growing in Australia, 1997.