Persea americana, widely known as the avocado plant, is an evergreen tree (semi-deciduous in cooler climates) that is native to Central America. It is cultivated all over the world for its nutritious fruits. Avocado has become an important plant in many cuisines due to its high nutrient and fat content, creamy texture, and distinct taste.
I. Appearance and Characteristics
The avocado, alligator pear or avocado pear (Persea americana) is a medium-sized, evergreen tree in the laurel family (Lauraceae). It is native to the Americas and was first domesticated in Mesoamerica more than 5,000 years ago. Then as now it was prized for its large and unusually oily fruit. The tree likely originated in the highlands bridging south-central Mexico and Guatemala.
The word avocado comes from the Spanish aguacate, which derives from the Nahuatl (Mexican) word āhuacatl , which goes back to the proto-Aztecan *pa:wa. In Molina’s Nahuatl dictionary “auacatl” is given also as the translation for compañón “testicle”, and this has been taken up in popular culture where a frequent claim is that testicle was the word’s original meaning. This is not the case, as the original meaning can be reconstructed rather as “avocado” – rather the word seems to have been used in Nahuatl as a euphemism for “testicle”.
The modern English name comes from a rendering of the Spanish aguacate as avogato. The earliest known written use in English is attested from 1697 as avogato pear, later avocado pear (due to its shape), a term sometimes corrupted to alligator pear.
Persea americana is a tree that grows to 9–20 m (30–66 ft) with a trunk diameter between 0.3–0.6 m (1–2 ft). The leaves are 8–25 cm (3–10 in) long and alternately arranged.
Flower
Panicles of flowers with deciduous bracts arise from new growth or the axils of leaves. The tree flowers thousands of blossoms every year. Avocado blossoms sprout from racemes near the leaf axils; they are small and inconspicuous 5–10 mm (3⁄16–3⁄8 in) wide. They have no petals but instead 2 whorls of 3 pale-green or greenish-yellow downy perianth lobes, each blossom has 9 stamens with 2 basal orange nectar glands.
Fruit
The avocado fruit is a climacteric, single-seeded berry, due to the imperceptible endocarp covering the seed, rather than a drupe. The pear-shaped fruit is usually 7–20 cm (3–8 in) long, weighs between 100 and 1,000 g (3+1⁄2 and 35+1⁄2 oz), and has a large central seed, 5–6.4 cm (2–2+1⁄2 in) long.
The species produces various cultivars with larger, fleshier fruits with a thinner exocarp because of selective breeding by humans.
II. How to Grow and Care
Sunlight
Like most tropical plants, the avocado tree thrives on a lot of sunshine. Plant this tree in a location where it can receive at least 8 hours of sunlight every day. These trees can tolerate partial shade, but grow best and produce more fruits when kept in full sun.
Temperature and Humidity
These famous fruit trees can only be grown outdoors in USDA hardiness zones 9 through 11, limiting an avocado tree to climates that are tropical and subtropical, unless you decide to grow an avocado tree indoors.
They are frost-sensitive and grow best in temperatures between 50°F and 85°F. Though prolonged temperatures around 30°F will be too cold for avocado trees, they should be able to withstand an occasional, very brief freeze.
Watering
Avocado trees benefit from infrequent, deep watering. This encourages deeper, stronger root growth. Wait until the soil begins to dry out, then water deeply. During the summer months, the avocado tree will require more frequent watering.
Young trees also require more frequent watering as they become established. Mature trees should receive around 2 inches of water per week.
Soil
Avocado trees prefer rich, loamy, and well-draining soil. A soil pH that is acidic to neutral, between 5 and 7, is ideal; it’s sensitive to alkaline soil.
Adding a layer of mulch around the tree can help the soil retain the right amount of moisture and will offer protection to the avocado tree’s shallow root system. Don’t mulch any closer than 6 inches from the trunk.
Fertilizing
Fertilizing an avocado tree starting in the late winter to early spring and feeding until the fall, depending on the specific instructions included with your chosen fertilizer. Fertilizers specifically designed for avocado or citrus trees work well.
Planting Instructions
It is best to plant avocado trees outdoors in the spring, allowing ample time to become established before winter temperatures arrive. Plant your avocado tree in a location with plenty of sunlight and well-draining soil. If soil conditions are less than ideal, amend the soil with sand or another well-draining substrate before planting.
The trees are vulnerable to high winds, so immature trees may benefit from support. Choosing a planting location that offers wind protection will help keep your tree upright and healthy. It should be at least 10 feet away from structures.
The avocado tree’s root system is sensitive, so try not to disturb the roots during planting. Dig a hole that is wider than the root structure and the same height as the root ball.
Pruning
If avocado trees are grown from seed, start pruning when the seedling is only 6 inches tall, snipping off the top pair of the leaves. When it reaches a foot in height, trim it back 6 inches. After this, prune the tree yearly.
Mature trees require occasional pruning. Light pruning can be done any time of year, though heavy pruning should be done in the early spring. Prune thick areas to ensure adequate light and airflow. Cut back any dead wood and trim away V-shaped branches. Don’t take off more than one-third of the length of each branch.
How to Grow From Seed
Starting an avocado tree from seed is a fun, simple project. However, it is important to keep in mind that seeds will not produce trees identical to the parent tree.
To do this, you will need an avocado seed, a jar of water, toothpicks, a sharp knife, a small pot, and well-draining potting soil. Then follow these instructions:
- Using a sharp knife, poke three or four holes around the circumference of the avocado seed.
- Poke the toothpicks into the holes. This will create the support needed to suspend the seed in water.
- Submerge the thick, or bottom end, of the seed into the water. Around one-third of the seed should be in the water.
- Place the seed in a sunny location and change the water daily.
- After a few weeks, roots should form and leaves should appear at the top of the seed.
- Once this occurs, gently plant the seed in well-draining soil.
How to Grow in Pots
Avocados can be grown in pots outdoors, though it will stifle their growth. (They can also be grown indoors in pots.) This is ideal for small yards or gardens near the northern edge of the avocado’s growing zones, as potted trees can be moved to a protected area when cold weather arrives.
Young trees or dwarf varieties are ideal for growing in pots as these will stay small for some time. When choosing a container, be sure it drains well and has unobstructed drainage holes, ideally a terracotta pot since it’s more breathable.
Propagation
Propagation is often done through grafting, layering, or cuttings. Grafting is often done to combine the desirable qualities of two different varieties of avocados while layering and starting cuttings are done to produce duplicate trees. Here’s how to perform each method of propagation:
Propagating an Avocado Tree From Cuttings
You will need sharp snips, moist and well-draining potting soil, a small pot, and IBA rooting hormone.
- In the spring, select new growth that is 5 to 6 inches long and has several leaves that have not opened.
- Using sharp snips, cut the new growth branch at a 45-degree angle.
- Wound the cut end by scraping at the bark on either side of the cutting. This will encourage root production.
- Dip the cutting into IBA rooting hormone.
- Bury the cut end into moist, well-draining soil.
- Keep the soil moist and place the cutting in a sunny area.
- After a couple of weeks, gently tug the cutting to check for resistance, which indicates root growth. Repot the cutting into a larger pot or outdoors.
Grafting an Avocado Tree
You will need sharp snips, a sharp knife, and something to cover the grafted area, such as grafting tape.
- Follow steps 1 and 2 as if you are taking a cutting.
- Remove the tip of the cutting, along with any leaves that are present.
- Then, wound the tree you would like to graft onto by removing a section of bark.
- Make sure the cambium of the cutting and the cambium of the tree are touching.
- Secure the cutting onto the tree with grafting tape, making sure to cover the exposed areas.
- In a few weeks, the grafted branch and the main tree should be fused together.
Air Layering an Avocado Tree
You will need a sharp knife, a rooting medium that can be wrapped around a branch, and rope or tape to secure the rooting medium around the tree.
- Select the branch you would like to take as a new tree.
- Using a clean knife, cut two circles around the branch to create a section of bark that can be peeled away.
- Once the bark is removed, scrape the inner branch to clean the cambium away.
- Wrap the exposed inner branch with rooting material, such as compost in a small bag (make sure the compost is wrapping the branch, not the bag) or another rooting medium. Secure around the branch with rope or tape.
- In several weeks, roots should develop. When this occurs, remove the bag, cut the branch off below the formed roots, and plant the new tree.
Overwintering
When grown in the appropriate zones, avocado trees do not require extra care during the winter unless the area experiences a frost. Protect the tree from a cold front by wrapping it loosely in burlap and adding extra soil at the base of its trunk until the frost has passed.
For trees grown on the northern edges of their growing zones, it is best to keep them in pots so they can be moved to an area protected from cold weather.
Pests and Diseases
Common pests that may bother an avocado tree include mites, caterpillars, borers, lace bugs, and thrips. Diseases include root rot, fruit rot, sun blotch, and cankers. Be alert to the presence of these pests or early signs of disease. Prompt action is the best way to remedy any developing problems before they threaten the health of your avocado tree.
III. Uses and Benefits
- Ornamental uses
Avocado is cultivated for itsedible fruit. This tree typically only grows in hot, dry climates and can be difficult to develop. However, it can be grown as a garden ornamental or as an indoor potted plant, without producing fruit. In outdoor landscapes it is considered a successor plant, growing where other plants have already resided.
- Culinary uses
The fruit of horticultural cultivars has a markedly higher fat content than most other fruit, mostly monounsaturated fat, and as such serves as an important staple in the diet of consumers who have limited access to other fatty foods (high-fat meats and fish, dairy products). Having a high smoke point, avocado oil is expensive compared to common salad and cooking oils, and is mostly used for salads or dips.
A ripe avocado yields to gentle pressure when held in the palm of the hand and squeezed. The flesh is prone to enzymatic browning, quickly turning brown after exposure to air. To prevent this, lime or lemon juice can be added to avocados after peeling.
The fruit is not sweet, but distinctly and subtly flavored, with smooth texture. It is used in both savory and sweet dishes, though in many countries not for both. The avocado is common in vegetarian cuisine as a substitute for meats in sandwiches and salads because of its high fat content.
Generally, avocado is served raw, though some cultivars, including the common ‘Hass’, can be cooked for a short time without becoming bitter. The flesh of some avocados may be rendered inedible by heat. Prolonged cooking induces this chemical reaction in all cultivars.
It is used as the base for the Mexican dip known as guacamole, as well as a spread on corn tortillas or toast, served with spices. Avocado is a primary ingredient in avocado soup. Avocado slices are frequently added to hamburgers and tortas and is a key ingredient in California rolls and other makizushi (“maki”, or rolled sushi).
In addition to the fruit, the leaves of Mexican avocados (Persea americana var. drymifolia) are used in some cuisines as a spice, with a flavor somewhat reminiscent of anise. They are sold both dried and fresh, toasted before use, and either crumbled or used whole, commonly in bean dishes.
IV. Harvesting and Storage
In Persea genus, Avocado (Persea americana) and Redbay (Persea borbonia) are the two well-known edible species. Commonly, Avocado fruits are for eating raw whereas leaves of the Redbay are used as tea or flavorings in soups or curries.
The fruit of Avocado can be harvested from early summer till winter, depending on the cultivar and planting region. The tree starts to produce fruit from about 4 years old. As the fruit will not get soft on the tree, you are recommended to harvest right before eating. Harvest fruits can be stored under a low temperature of about 10 ℃.
As for Redbay leaves using. These can be fresh or dried leaves. These leaves can be harvested throughout the year but are recommended to harvest in spring for the best flavor. To dry the leaves, simply hang them in a warm, dry area for three weeks. These should then be kept in an airtight container and used within six months.
The Persea tree does bloom in spring, but the flowers are considered insignificant and therefore not harvested. You may also notice small fruits on the Persea tree other than Avocado as well, but these are not suitable for human consumption.