Avocado Tree (Persea americana)
The Avocado Tree is one of the most common fruit trees in the world and it makes a perfect specimen for gardens in tropical and sub-tropical areas. It does require a frost-free environment but there are slightly more cold-tolerant varieties available, allowing it to be grown as far south as Melbourne.
Easy to grow and highly rewarding, it looks stunning when the whole tree is in bloom; dripping with panicles of greenish-white star-shaped flowers. It also has the added bonus of being able to provide you with a high yield of the ‘super-food’ Avocado fruit.
This popular evergreen tree is well suited to domestic gardens. It develops a lovely dense, natural growth habit but is also easy to prune to maintain a smaller size if required. The Avocado Tree is suitable for container growing meaning it can be grown as a patio plant, easily transferred indoors for winter protection. It also makes a really lush house or office plant.
Here at Designer Trees we have Avocado Trees in a wide range of sizes and varieties, including some slightly more cold tolerant Avocado Trees such as ‘Bacon’. Commercially grown Avocados are often grown by grafting and various types of rootstock are becoming more widely available. This means you can select a rootstock (e.g. a dwarf rootstock for container or small garden planting) that is well suited to your chosen planting area. We are always on hand and happy to help you to select the perfect specimen for your home.
Avocado Trees: Planting
As a tropical/subtropical plant, the Avocado Tree needs to be planted in a sunny position with protection from frost. The more sun it gets the more fruit it produces. In areas susceptible to winter temperatures lower than 5-10C the tree is best planted into a pot so that it can be moved indoors during the colder months.
Avocado trees also need to be sheltered from the wind. They like a high humidity level to prevent the flowers from becoming dehydrated. Exposure to drying winds reduces humidity levels causing pollination problems and therefore less prolific fruiting. The branches can also be quite brittle and are prone to breaking in high winds.
Bear in in mind that The Avocado is a rainforest tree when it comes to growing conditions and you won’t go far wrong. As you would expect, it develops a lush, leafy canopy that creates a lot of shade and it does drop quite a lot of leaves. These conditions should be considered if you are planning to plant your tree amongst an existing planting scheme as light levels on the ground will reduce as the tree matures.
It has a shallow root system which can quickly dry out so is best planted in a humus-rich, moist but well-drained soil with a neutral pH. It doesn’t do well in alkaline soil and will often develop chlorosis (a yellowing of the leaves) if grown in this soil type. Sharp sand or gravel should be incorporated into the planting hole or potting mix and the application of a thick mulch after planting will prevent water loss. Do not mulch too close to the trunk as this can cause rotting.
Container grown plants must be raised slightly from the ground so that the water can drain freely from the holes at the base of the pot. The most common cause of problems when growing the Avocado Tree is soil saturation – it absolutely hates to have its roots sat in water as this leads to rotting.
Avocado Trees: Ongoing Care and maintenance
Such an easy to grow tree, the Avocado requires very little ongoing care and maintenance. It needs no pruning to maintain health and is self-pollinating. Fruit can be left on the tree for several months as it doesn’t ripen until picked. In the wild, this usually takes 1-2 weeks after falling naturally.
All that is needed is protection from frosts in cold prone areas and regular, deep watering to prevent the soil from drying out.
Avocado Trees can be prone to pests and diseases so it is advisable to monitor regularly for signs of any potential problems. Some of the most common ones to look out for are whitefly and spider mite if grown in a glasshouse, thrips, mealybug, fungal leafspots, root rot and phytophthora.
Biennial-bearing, where fruiting is prolific one year and sparse the next, is common in some Avocado Tree cultivars so a reduced yield is usually not an indication of problems with your tree. It is also worth noting that in some years, environmental conditions can cause the appearance of seedless fruit which again is nothing to worry about.
Fruiting is most prolific in areas where, during the flowering period, nighttime temperature stay above 10C and daytime temperatures below 25C until the fruit has set.
Avocado Trees: Propagation
Commercially, Avocado Trees are propagated by grafting and layering. The industry has, over recent years, been developing in the area of grafting and rootstock production leading to a wider range of Avocado Trees being available for different planting and growing requirements.
Avocado trees are really fun and easy to grow from seed. Seed grown plants won’t produce fruit for at least 4-6 years, sometimes longer, but they are great to grow as container specimens that you can dot around the house and garden to quickly provide an abundance of lush, tropical foliage in your home.
To grow an Avocado Tree from seed, push three toothpicks into the sides of the seed at a slightly upward sloping angle. Suspend the seed, pointed end upwards, above the opening of a clean jar of water. Maintain a water level that covers approximately half the seed and place in a bright spot, but away from direct sunlight. Your seed should sprout in around 4-8 weeks, depending on how warm the environment is.
Once the shoot has emerged, remove the seed from the jar and plant into a general-purpose compost with added sharp sand to aid drainage. Take care not to damage any roots or shoots when transplanting the seed.
Water regularly to ensure that the soil never dries out but always remember, this plant should not have its roots sat in waterlogged soil!
Avocado Trees: Taxonomy and Naming
Genus: Persea (From Latin and Greek ‘persea’ meaning a fruit-bearing, tropical ornamental tree or shrub)
Species: americana (meaning typical of the USA)
Laurus persea, Persea gratissima and many more. See http://www.theplantlist.org/tpl1.1/record/kew-2529835 for the full list
Avocado, Alligator Pear, Avocado Pear, Butter Fruit
The word ‘avocado’ comes from the Spanish ‘aguacate’ which in turn comes from the Aztec word ‘ahuacatl’ meaning ‘testicle tree’.
Avocado Trees: History
The Avocado Tree is a variable species and therefore it is quite difficult to pinpoint its exact origin. It is thought to originate from Central Mexico but archeological evidence suggests that similar species were much more widespread. There is evidence of three separate domestications of the Avocado – Mexican, Guatemalan and West Indian races. Each race has their own unique characteristics.
A long history of cultivation in Central and South America has been documented, possibly going back to 5000BC. An avocado pit found in a cave in the Tehuacan Valley of Mexico has been dated to around 9-10,000 years old!
It is thought that the native, undomesticated variety know as ‘Criollo’ co-evolved with now extinct megafauna (giant animals-dinosaurs!) who would have eaten the small black fruits and distributed the seeds far and wide through their droppings.
Being such a high value tree, the Avocado began to be introduced to the rest of the world at the start of 1600’s, and was brought to Australia in the late 19th century.
Avocado Trees: Distribution and Habitat
The Avocado Tree is thought to originate in South and Central Mexico, and Central America. It is found growing in the highlands of Mexico & Guatemala, and lowlands of the West Indies, most commonly growing in rainforest areas at altitudes of 700-1500m.
Local adapted, traditional varieties have developed over time bringing diversity to the species and it is now cultivated commercially in Mexico, Peru, California, New Zealand and South Africa. Introduced to Australia in the late 19th century, it has become naturalised in North Eastern Queensland.
Avocado Trees: Appearance
The Avocado Tree is an evergreen tree with a lovely natural habit and dense green foliage. Small greenish-white star shaped flowers are followed by pear shaped, dark green fruits with edible flesh. A vigorous but relatively short lived tree, it can grow to heights of 10m or more over 10-20 years.
Lance shaped or elliptic, evergreen leaves are alternately arranged along the branch and measure approximately 10-30cm long and 4-10cm wide.
Terminal buds are covered in lots of pale, silky hairs.
Greenish-white star like flowers appear from leaf axils on new growth, from Winter to early Spring. At only 5-10mm the flowers are insignificant individually but, as they grow in panicles of up to 600 individual flowers, when the whole tree is flowering at its peak it makes a stunning sight.
The Avocado fruit is a green, usually rough skinned, single seeded berry. It has a pear shaped, fleshy body that measures between 7-20cm long and approximately 7cm in diameter. The large seed can measure between 4-6.5cm. The fruit is climacteric, growing to maturity on the tree and then falling to the ground where it ripens, usually 7-10 days later.
The Avocado is usually self pollinating but it is worth noting that the tree has two different types of flowers – Type A and Type B.
- Type A flowers open as female and are receptive to pollen during the morning of the first day. The following afternoon they open as male and release pollen.
- Type B flowers open as female and are receptive to pollen during the afternoon of the first day. They reopen as male and release pollen the following morning.
When purchasing an Avocado Tree you may come across ‘A cultivars’ & ‘B cultivars’ and this is referring to the type of flowers, as described above, that the cultivar has.
Avocado Trees: Uses
Due to the avocados popularity as a modern health food the Avocado Tree is a commercially valuable and widely cultivated in tropical and Mediterranean climates around the world.
It has a wide variety of culinary uses and is a great source of ‘good’ mono-unsaturated fats and protein. It is also very high in essential vitamins and minerals. The leaves of Persea Americana var drymifolia are sometimes used as a spice. It has an anise like flavour and is commonly added to bean dishes.
The Aztecs considered the avocado to be a fruit of fertility and the Mayans used it as an aphrodisiac.
The avocado pit, when crushed, releases a milky liquid that turns red or black when exposed to the air. It has been used as an ink for writing and also as a natural dye.
The oil is very nourishing to the skin and hair and is widely used as a natural ingredient in hair and beauty products.
Avocado Trees: Toxicity
The Avocado Tree is considered as highly toxic to almost all animals.
The seeds and leaves are poisonous to humans and occasionally consumption of the fruit can lead to an allergic reaction.
There are two main types of allergy:-
- Hayfever type reactions of swollen and irritated airways.
- Latex-fruit Syndrome reactions of urticaria, abdominal pain and vomiting.
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