How to Grow Avocado Trees in Gardens
The fruit of an avocado tree is called avocado fruit. It also has other names such as alligator pear and avocado pear. This tree is classified as a member of the Lauraceae family. Indigenous to southcentral Mexico, these plants are cultivated in many countries with tropical and Mediterranean climates. To maintain the quantity and quality, growers often graft these partially self-pollinating trees for propagation.
This article focuses on avocado trees, their description, propagation, caring and uses.
Botanically, the fruit is a large berry with a single central seed. Upon ripening, the fruits of domesticated varieties have buttery flesh with a nutty flavor. Depending on the variety, the skins of the fruits have various colors like purple, black, brown, or even green. They also have different shapes such as spherical, oval (egg shape), or pear.
In 1696, Hans Sloane coined the term ‘avocado’ in English, while indexing Jamaican plants. This plant entered Spanish markets in 1601, Indonesian markets in 1750, Mauritian markets in 1780, Brazilian markets in 1809.
However, this plant was introduced in the US mainland only in 1825. Later, Henry Perrine, a horticulturist planted these trees in Florida in 1833. To his part, R.B. Ord, a Judge, planted these trees in California (Santa Barbara) in 1871.
At those times, the Californians and Floridians called these fruits ahuacate and alligator pears respectively. In 1915, the popular California Avocado Association referred to these plants officially as avocados’. In spite of its popularity in the cultivating states, this fruit gained countrywide acceptance in the mid-1950’s only. However, the cultivating states began growing this crop commercially in the early twentieth century itself.
Photo by Ethel Aardvark (Wikimedia Commons) (CC BY 3.0)
Typically, the avocado trees grow about 66 feet (20m) high. Measuring about 5 – 10 inches (12 -25 cm) in length, the leathery leaves are dark green in color. Having deciduous bracts, panicles of flowers sprout out from the axils of leaves. Naturally, the greenish-yellow flowers are inconspicuous and measure about 3/16 – 3/8 inches (5 – 10 mm) wide.
Biologically, the fruit is a single-seeded berry as an imperceptible endocarp covers the central seed. Usually, the pear-shaped fruits measure about 3 – 8 in (7 – 20 cm) long and weigh between 3 1⁄2 and 35 1⁄2 oz (100 – 1,000 grams).
Types of Avocado Trees
Primarily, there are about three types of known avocados. They are West Indian, Mexican, and Guatemalan. West Indian is the least cold-tolerant type and Mexican is the most cold-tolerant type.
Hass, a popular variety in US is a hybrid of Guatemalan and Mexican types.
Rudolph Hass, an amateur horticulturist, accidentally discovered Hass avocados. In the late 1920s, he purchased some seedlings from Whittier, California. Interestingly, an anomalous tree grew among the seedlings as pointed out by his children.
Initially, he decided to cut the tree. But his children said the fruits are delicious than other avocado varieties and stopped him from doing so.
Confirming the fact, he named the variety after himself and patented it. Then, he signed an agreement with a commercial grower for growing this wonderful tree. Today, the Hass variety constitutes more than 80% of US-grown avocados. Interestingly, Rudolph Hass’s ‘anomalous tree’ is the ‘Mother’ of all these trees.
Sharwil avocados are largely grown in Hawaii. These are also a hybrid of Guatemalan and Mexican types. Sharwil is one of the tallest growing avocado varieties.
To deal with invasive pests associated with Sharwil, the USDA imposed complex regulations on its imports. Hence, this variety is not available in all the US states.
The Avocado trees have the ability to self-pollinate. During the flowering periods, the trees produce more than a million flowers. The purpose is to attract pollinators. However, most of the flowers fall off without fruiting.
The flowers have both male and female parts inside them. They also exhibit a usual behavior known as protogynous dichogamy. In a course of a 2-day period, all the flowers of a tree will function as female on the first day and male on the second day.
Typically, this functionality lasts only half a day and they remain closed on the other half of the day. Ideally, the temperature needs to be between 20 C – 25 C for this sequence to take place successfully.
Depending on the flower opening sequence, the avocado trees are divided into two types – type A and type B
Morning (Day 1) – Female
Afternoon (Day 1) – Closed
Morning (Day 2) – Closed
Afternoon (Day 2) – Male
Morning (Day 1) – Closed
Afternoon (Day 1) – Female
Morning (Day 2) – Male
Afternoon (Day 2) – Closed
Usually, the growers inter-plant type A trees with type B trees to increase the pollination.
Propagation of Avocado Trees
Photo by Afifa Afrin (Wikimedia Commons) (CC BY-SA 3.0)
Generally, avocado trees prefer to thrive under full sun. Though some Mexican varieties can handle cool winters, it is recommended to offer them protection. Also, these trees don’t like to grow crowded. Hence, avoid planting them closely near buildings or other trees.
In fact, these trees can thrive in a wide range of soils with various pH levels. However, well-draining coarse-textured (sandy, loamy) soils are best to grow these trees. In any case, avoid high saline-containing soils.
Start the propagation in the spring. This helps the tender plants to grow healthily with fresh energy.
1) Dig a hole deep so as to accommodate the container itself.
2) Do not add compost or fertilizer. Instead, backfill the hole with a little loose dirt up to a few inches.
3) Carefully remove the seedling from the container, without disturbing the sensitive roots.
4) Place the seedling upright and cover the hole with dugout mud. Make sure the root ball is fully under the ground.
5) After mulching, water the plants deeply.
This method sometimes takes up to 10 years for fruiting, depending on the variety and climate.
This method involves a twig (scion) and a rootstock (roots and lower trunk). Simply, graft a variety of avocado twig into a rootstock of another variety. In this method, you can expect fruiting within 2-3 years.
You can also grow rootstocks yourself. Normally, the seeds take about 4 – 8 months to grow into seedlings strong enough to act as rootstocks. However, the West Indian varieties grow faster comparatively. If you plant them in spring, they will grow by September or October.
Generally, it is difficult to root the avocado hardwood cuttings. Commercial growers use advanced techniques like Aeroponics or hydroponics to root the cuttings. Still, the results show mixed success.
Although the west Indian cultivars root from cuttings, it is not easy in other cultivars. Hence, most home growers avoid this method.
You can also grow avocados indoors. As the plants grow, you may need to re-pot them several times. It may take about 5 – 13 years for fruiting if they get enough sunlight.
1) Remove the pit carefully from the fruit. Then, soak it in water for 5 -10 minutes and scrub all the sticking flesh. After that, wash the pit thoroughly in running water. Do not peel off the brown skin.
2) Normally, the top end of the pit is slightly pointed up. The seedlings sprout out from this end. On the other hand, the bottom end is slightly flattened. The roots sprout out from this portion.
3) Insert four toothpicks evenly spaced around the top portion. Slightly angle the toothpicks upwards. This helps to keep most part of the seed immersed.
4) Keep this arrangement on a glass of water. Place the glass in a location like a window sill that receives full sunlight. Then, replace the water at least once a week.
5) Normally, the sprouting process completes within a month or so. Initially, a crack appears at the top, extending to the bottom with time. Then, the taproot emerges at the bottom and grows longer. After that, the seedlings sprout up from the top.
6) When the roots grow about 6-7 inches long, cut them in half. This helps encouraging fresh growth. Again, the roots will grow about 6-7 inches in a few days.
7) At this stage, take the pit out and pot it in rich humus soil, removing the toothpicks. Make sure to expose the top end of the pit.
8) Place the pot in a place like window sill that gets a lot of sunlight and water deeply.
Caring Avocado Trees
During the first week of planting, water the plant every alternate day. Then decrease the watering frequency to about once a week gradually.
In the early years, feed your trees with 1/4 pound of 10-30-10 fertilizer with zinc every two months. As the trees mature, feed them 1 pound of 10-5-20 fertilizer with zinc every six months.
Generally, these trees seldom require pruning. In fact, the spreading varieties require little to no pruning. Tall growing varieties may require careful pruning to keep the fruits within reach. To encourage lateral branching, just prune the terminal buds.
Pests and Diseases
There are a few common pests that invade avocado trees. They include caterpillars, thrips, mites, borers, scales, and lace bugs. In most cases, the pests do not succeed in damaging the trees seriously.
We also recommend planting the right varieties at the right locations. Local extension offices can help in this regard.
To treat the borers and caterpillars use Bacillus thuringiensis. Other pests like mites, thrips, scales, etc., can be effectively treated with neem oils.
These trees are also vulnerable to fungal infections. The symptoms include decoloring, wilting foliage. You can use specific fungicides to deal with these diseases.
In fact, keeping the garden free from debris and weeds is the best way to prevent various pests and diseases. Pull out the weeds regularly. Rake and dispose of the debris immediately.
Harvesting Avocado Fruits
Generally, harvesting avocado fruits is a challenging task. Different varieties mature at different periods. It requires a lot of experience and skills. Unlike other fruits, Avocados are harvested when green and hard. They usually ripen off the tree. Typically, growers harvest these fruits in September.
During September, note the color changes on larger fruits. Upon maturing, some varieties even develop rusty-brown small spots on their skins. Pluck one or two such fruits and store them at room temperatures for about a week. If they ripen fully, they will become soft and ready to eat. In this case, you can continue the harvest and allow the fruits to ripen off the tree.
On the other hand, if the fruits are bitter to taste and become leathery, shrivel, shrink, rot Etc., they are still immature to harvest. So, stop the harvest and repeat the testing after a few days.
Uses of Avocado
Consuming Avocados has various health benefits. Some of them are elaborated below.
Avocado fruits are rich in nutrients. USDA National Nutrient Database claims, 40 grams of avocados contain 3.4 grams of carbohydrate, 64 calories, less than a gram of sugar, about 3 grams of fiber, and 6 grams of fat.
Avocados are also a good source of vitamins (B-6, C, E, K), riboflavin, potassium, magnesium, pantothenic acid, niacin, and folate. In addition, they provide omega-3 fatty acids, lutein, and beta-carotene
Both Avocado fruits and their oils are rich in a heart-healthy fatty acid, called monounsaturated oleic acid.
Great for vision
Generally, these fruits are rich in antioxidants including zeaxanthin and lutein. These nutrients are important for healthy eyes. They also lower the risk of cataracts and macular degeneration.
Avocados are high in Vitamin K. Intaking Vitamin K increases calcium absorption and reduces the excretion of calcium through urine. Thus, these fruits support healthy bones.
Avocados contain nutrients that can lower the side effects of chemotherapy and prevent prostate cancer. Although test-tube studies confirm the results, human-based research is still not done.
Avocados contain Folate. This nutrient plays an important role in a healthy pregnancy. It also deals with neural tube defects and reduces miscarriage risks.
Typically, bacteria like Escherichia coli cause food poisoning. In fact, some nutrients in Avocados have antimicrobial activity against these types of bacteria.
Avocados also have many other health benefits including aiding digestion, lowering the risk of depression, helping lose bodyweight, Natural detoxification Etc.
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