In Melbourne, spring and summer are particularly critical for citrus trees. Care or lack of it, during this period will determine tree health, size and quality of crop
Citrus trees have very shallow root systems so never cultivate the soil under the tree.
Maintain a 5-10cm deep straw mulching. Keep the mulch clear of the trunk to minimise the danger of trunk or collar rot. Avoiding using woody mulches such as bark and wood chips as this can cause nitrogen draw down, which will starve the tree.
Lawn, garden plants and weeds will all compete with citrus trees for moisture, nutrients and root space and should be minimised.
Avoid growing plants under the drip line of the tree, particularly aggressive plants such as ivy or wandering Jew.
Citrus trees perform best with uniform moisture in their root zone from September through to April. Water requirements can be hundreds of litres for a large tree in summer. See the table below for recommended quantities
Minimum weekly water requirements (litres), for well mulched citrus trees, watered at night through drip irrigation. Given annual rainfall of 500-700 mm and a dry summer. Tree size is average height and width in metres.
Citrus trees have a high demand for nutrients. Adequate amounts of all the essential nutrients, in correct proportions are necessary to grow healthy trees, and produce quality fruit. Fertilizing of sandy soils must be carefully watched as nutrients are readily leached out of the root zone by rainfall and watering.
Citrus fertilizers for the home gardener can include blood and bone (with added potash), poultry manure (pelletised or well-rotted), compost or a commercially formulated citrus food. Check out our fertilizer trial to see which fertilizers might be best for your citrus trees.
Traditionally you should apply nitrogen rich fertilizers, especially in the spring and early summer period (mid-September to mid-December). However, we’re noticing an increased susceptibility to Citrus Gall Wasp when trees are fed in spring. Take a look at our citrus gall wasp blog post for more information on this.
Do not fertilize after February, as this will stimulate leaf growth into autumn and winter (making the tree susceptible to frost damage and infestation with citrus leafminer).
Some citrus will ripen in 7 months; others take 12 to 14 months from flowering. Some fruit keep their condition on the tree for months after they have ripened. Others lose peak condition quickly and can become coarse, dry, puffy or poorly flavoured. Fruit picked under-ripe does not continue to mature off the tree. However taste may become sweeter after storage. Taste test remain the best indicator of fruit ripening.
Harvesting should be performed with care. Snip the fruit from the tree, rather than pulling or twisting. This will minimise the potential for disease entry to both the tree and the fruit.
All fruit should be removed from the tree for the first 3 to 4 years to avoid over working the tree.
Want to know more about Growing Citrus in Melbourne?
This is Part 3 of a 5 part guide to growing citrus in Melbourne. The links below will take you to the other four parts of our Melbourne citrus growing guide.
Our citrus growing guides are based on my own experience, as well as the following two books. They are both invaluable resources for the home gardener based in Melbourne. I strongly recommend you have a read of both if you want to know more about growing citrus in Melbourne:
Bruce Mophett & Ian Tolley: Citrus, A Gardener’s Guide, 2009.
Louis Glowinski: The Complete Book of Fruit Growing in Australia, 1997.