In the decades before they became a cultural phenomenon, Australians mostly consumed avocados in only two dishes — served with a salad or accompanying prawn cocktails. But that has certainly changed!
In the last ten years, the consumption of what we affectionately call “avos” has tripled in Australia, and the avocado industry is now worth around $460 million. With a range of health benefits, nutty taste and creamy-almost-buttery texture, it has become one of our country’s favourite fruits.
So if you’re a fan (if not, we dare you not to like restaurateur Bill Granger’s now-famous smashed avocado recipe), why not add an avocado tree to your homegrown- fruit-and-veg collection? For inspiration, read on for a deep dive into the origins of the avocado, the varieties and how to grow an avocado tree.
Because it is classified as a member of the flowering plant family Lauraceae, avocados are actually fruit, not vegetables. Botanically, an avocado is a large berry containing a single large seed. Depending on the variety, avocados have brown, green, purplish or black skin when ripe and may be egg-shaped, spherical or pear-shaped. The avocado tree (Persea americana) has alternately arranged leaves and inconspicuous, greenish-yellow flowers.
If your garden is on the smaller side, you might be asking yourself, how big do avocado trees grow? The answer depends on the variety of tree, which can also affect its form. A full grown avocado tree can reach a height of twenty metres, although a height of between five and ten metres is the average. Dwarf varieties are also available, which are obviously much smaller.
The English word “avocado” is a transliteration first used in the late 1600s of the Spanish word aguacate, which came from the Nahuatl name for the indigenous fruit, āhuacatl. Interestingly, this word derived from the proto-Aztecan word meaning testicle! Before 1915, the avocado was commonly referred to as ahuacate, avocado pear or alligator pear due to its shape and the rough green skin of some cultivars. The California Avocado Association introduced the term avocado in 1915.
The avocado tree is an evergreen plant that possibly originated in the Tehuacan Valley in Mexico, although fossil evidence suggests that similar species were much more widespread millions of years ago. The oldest discovery of an avocado pit (seed) dates from around 9,000 to 10,000 years ago. The avocado tree also has a long history of cultivation in Central and South America, likely beginning as early as 5,000 BC.
Avocados first arrived in Australia in 1840 in seed form and were planted in the Sydney Royal Botanical Gardens. Further commercial imports of seeds and plants continued over the next 110 years until the late 1960s, when a developing Australian industry began to take shape.
In 2020, global production of avocados was 8.1 million tonnes, led by Mexico with 30 percent of the total. The Mexican state of Michoacán is the world leader in avocado production, accounting for 80 per cent of all Mexican output. Most Mexican growers produce the Hass variety due to its longer shelf life for shipping and its high consumer demand. Other significant producers are Peru, Columbia, Indonesia and the Dominican Republic.
The two main varieties of avocados that are commercially grown in Australia are Hass and Shepard. Because avocados are a perennial fruit, premium produce of these varieties is generally available year-round because of the widespread and climatically-diverse growing regions. The highest volume of fruit is available between March and November.
According to a report released by Avocados Australia, Australia produced nearly 88,000 tonnes of avocados in 2019/20, and the gross value of production (GVP) for Australian avocados was estimated at $493 million. Queensland continues to produce the majority of Australian avocados, but avocado orchards are also found in New South Wales, Victoria, South Australia, Western Australia and Tasmania.
The avocado is an unusual plant in that avocado flowers are botanically “bisexual”. This means they carry both male and female reproductive organs, but the timing of the male and female flower phases differs among cultivars.
The two flowering types are A and B. A-cultivar flowers open as female on the morning of the first day and close in late morning or early afternoon. They then open as male in the afternoon of the second day. Essentially this means that the flowers are ready to be pollinated in the morning, but any blossoms flowering in the afternoon are releasing their pollen. B varieties open as female on the afternoon of the first day, close in late afternoon, and reopen as male the following morning. This means they release pollen in the morning and are ready for fertilising in the afternoon.
Single A-type trees fruit well in cool climates, but multiple A and B-type pollinators are often both needed in warm climates where spring temperatures are over 20°C by day and over 10°C at night. These grafted trees fruit in two to three years.
There are many other grafted varieties available at nurseries, and some of the newer varieties are protected by plant breeders’ rights and may attract a royalty when purchasing. Some of these include:
Growth cycle of the avocado
Avocado trees are one of the very best Australian fruit trees, and growing an avocado tree is a relatively straightforward process. However, it is recommended that you buy trees from an Avocado Nursery Voluntary Accreditation Scheme (ANVAS) accredited nursery, as they are free from root rot and other diseases. A named, grafted cultivar from a nursery will also crop in three to five years as opposed to a seed-grown tree that may take up to seven years.
Grafting is the process of biologically jointing two sections of different trees. In terms of avocados, nurseries will generally graft an avocado cultivar branch (the scion) to the rootstock of another close relative. This speeds up the fruit-bearing process. However, it’s recommended you don’t try this yourself as you will need to source appropriate root understock, and the process isn’t easy, even for professionals!
It’s also important to note that many parts of the avocado plant can be highly poisonous to some animals, mainly cattle, horses, birds and goats. There have also been some reports of poisoning in dogs, so check with your vet before you plant.
Select a variety appropriate to your particular climate zones, as, although some trees can tolerate moderate frost and cold temperatures, many prefer warm, temperate, subtropical and tropical regions. Full sun is a must for avocado trees, and although they are relatively hardy, they still need a location protected from strong winds.
Avocado trees prefer deep, well-drained soil and tolerate soil from slightly acidic to slightly alkaline — anywhere from pH 6 to 7 is ideal. A few weeks before planting, improve the soil by digging through a combination of blood and bone and well-aged cow manure. Use a free-draining, good-quality potting mix if growing in a pot.
When planting an avocado tree in warmer areas, plant in April/May to avoid hot weather while the plant becomes established. In areas where frosts occur, plant during September/October.
Choose a spot that will allow the tree to spread, then dig a hole that is as deep as the roots and about twice as wide. Remove the plant from its pot, tease out its roots and position it in the hole. Then backfill, mulch with quality, organic mulch and water.
Avoid disturbing the tree’s roots when planting, as any disturbance can kill a young tree. Trees should also be appropriately staked with at least two stakes. Because avocado roots are wide-spreading, avoid planting near driveways, drains, buildings, pathways and swimming pools.
Young trees require regular watering as they establish, and older trees may need supplemental watering in dry periods. However, avocado trees hate having wet feet! A tree that remains waterlogged for as little as 48 hours can die, even if it’s mature.
That’s why maintaining well-aerated soil is a must. It will ensure the right nutrient balance and reduce the likelihood of Phytophthora root rot. Root rot generally is one of the most common tree diseases in Australia. After watering, the soil should always be moist but not saturated. Yellowing leaves are a sign of overwatering, so if you notice this, let the plant dry out for a few days. Avocado trees also won’t tolerate grey or salty water, so always use tap or rainwater.
The best fertiliser for avocado trees in Australia depends on the age of the tree. When young, feed regularly with a balanced, controlled-release fertiliser blended for fruit trees to avoid generating excessive leaf growth. When trees are mature and producing fruit, feed with a complete fertiliser or chicken manure, and repeat in summer and early autumn.
The ideal shape for an avocado tree is to have a spreading but dense crown, however generally, these trees require little pruning. To shape young trees, “pinch out” shoot tips. Prune adult trees after harvesting by removing dead, weak or crossing branches as they occur to avoid congesting the canopy. Never dig or hoe around the base of avocado trees as this can damage their fragile feeding roots.
Avocado trees are vulnerable to viral, fungal, bacterial and nutritional diseases, and they can affect all parts of the plant, causing spotting, pitting, rotting and discolouration. However, most issues affecting an avocado tree are related to excess water and fungal disorders. These can be avoided by planting in well-drained soil. Adding organic matter and gypsum can also minimise root rot issues.
In terms of pests, some varieties (like Bacon) are prone to fruit fly attacks, others to attacks by aphids and the pyriform scale insect.
Avocados mature on the tree but don’t ripen until they are picked. Maturing times for avocados vary depending on the climate, but avocados usually ripen earlier in tropical and subtropical climates and later in temperate and cooler zones. Fruit can generally be picked once it has finished swelling, but this involves a bit of trial and error.
One way of knowing if the fruit is ready for harvesting is to cut one off the tree with a bit of stalk intact, which will help complete the ripening process. Take it indoors, and if it ripens without shrivelling and is slightly soft, it’s time to pick the rest. It’s not essential to pick all the fruit at once, although leaving them too long on the tree may affect the following year’s fruiting potential.
An avocado tree growing from a pit/seed
Avocados are one of the easiest edible plants to grow from seed, and although it will take considerable time for them to grow to a decent size (potentially ten years or more), it’s well worth the wait if not just for the satisfaction of doing it yourself! Here is a step-by-step guide:
Need a little more inspiration to grow an avocado tree? Avocados are rich in unsaturated fats (specifically, monounsaturated fats), which are sometimes referred to as “good” or “healthy” fats. In fact, they are the only fruit apart from olives to contain monounsaturated fats. According to the peak industry body, Australian Avocados, avocados can:
The cost of an avocado tree depends on a range of variables, from its age and size to its variety and the quality of the cultivar. However, here is a general pricing guide for some of the more popular varieties.
References
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