Century plant (Agave americana)

Agave americana, or the American century plant, is a drought-tolerant, perennial plant used for ornamental purposes. The plant is also called American aloe but does not belong to the same family as aloe. It is characterised by greenish-yellow flowers and spatulate leaves, which are over six inches long. Here’s all you need to know to grow this plant in your home garden.

I. Appearance and Characteristics

Agave americana, commonly known as the century plant, maguey, or American aloe, is a flowering plant species belonging to the family Asparagaceae. It is native to Mexico and the United States, specifically Texas. This plant is widely cultivated worldwide for its ornamental value and has become naturalized in various regions, including Southern California, the West Indies, South America, the Mediterranean Basin, Africa, the Canary Islands, India, China, Thailand, and Australia.

Despite being called “American aloe” in common parlance, Agave americana is not a member of the same family as Aloe, although it falls under the same order, Asparagales.

The common name “century plant” stems from its semelparous nature of flowering only once at the end of its long life. After flowering, the plant dies but produces adventitious shoots from the base, allowing its growth to continue. Although it is called the century plant, it typically lives only 10 to 30 years. It has a spread around 1.8–3.0 m (6–10 ft) with gray-green leaves measuring 0.9–1.5 m (3–5 ft) in length, each with a prickly margin and a heavy spike at the tip that can pierce deeply. Towards the end of its life, the plant produces a tall, branched stalk adorned with yellow blossoms, which can reach a height of 8–9 m (25–30 ft).

II. How to Grow and Care

Sunlight

Like other agave species, century plants do best with full sun, so plant them in a location that receives at least six to eight hours of sunlight each day. However, it is possible to grow these plants in light shade if your site doesn’t meet the requirements for full sun.

Temperature and Humidity

The century plant is native to Mexico and Texas, providing an insight into the plant’s preferred temperature and humidity conditions. Warm temperatures with low humidity levels make for ideal climate conditions. Take note that the century plant is hardy to about 20 degrees Fahrenheit, but is likely to suffer damage from frost.

Watering

The long and fleshy leaves of the century plant are designed to store water during times of drought, so don’t hover around these plants with a watering can. However, these plants appreciate regular watering during the spring and summer growing season. Water deeply but then allow the soil to dry thoroughly in between watering sessions; this might be an interval of a week to a month, depending on climate conditions.

Soil

These plants do best in dry, sandy soil. They can tolerate a range of other soil types, including clay soil, but well-draining soil is an absolute requirement. Century plants in overly moist soil can develop root rot.

Fertilizing

It’s typically not necessary to fertilize a century plant. They do fine in sandy, nutrient-sparse soil. Like other agave species, these plants die after blooming so feeding with a fertilizer and accelerating the process only serves to shorten the plant’s lifecycle.

Planting Instructions

When planting an agave plant, it’s essential to choose a location with full sun exposure. Agaves need free-draining soil – typically composed of 50 per cent multi-purpose compost and 50 per cent horticultural grit or perlite – to ensure optimal growth.

Plant your agave at a slight angle to prevent water-logging of the plant’s crown and facilitate proper drainage of rainwater, which is particularly crucial when the plant is grown outdoors without the ability to regulate watering.

Placing rocks or large stones in the planting hole and around the base of the plant can both aid drainage and inhibit weed growth, as agaves can be challenging to weed around due to their spines.

Propagation

Like other agave species, century plants are most easily propagated from offsets. Also known as pups, these clones of the parent plant can easily be separated and planted independently. You won’t need many tools, because you can pull away the pups from the parent plant by hand in most cases. However, a small trowel can be useful and gloves will protect your hands from the spines of the parent plant. You will want to have a container or garden site ready with well-draining soil. Then, follow these steps to propagate:

• After protecting your hands and arms, locate a pup at the base of the parent plant. In some cases, there can be a few pups growing close together. Use the trowel to gently loosen and separate the pups.
• Grasp the pup at the base and wiggle it loose from the parent plant and soil. If necessary, use the trowel to separate the plant from the soil and roots attached to the parent plant. Leave a portion of the stem that connected to the offset to the parent, along with the pup’s root bundle. A bare base on the pup will be a challenging start to generating root growth.
• Pups can be planted directly in the ground or in a container. In both instances, be sure to use well-draining soil.

How to Grow From Seed

Growing a century plant from seed is fairly uncommon because the plant only flowers once in its lifetime only after several decades of growth. The much more common way to propagate a century plant is from offshoots, which it will regularly produce throughout its lifetime.

Potting and Repotting

Century plants can be grown in pots, but keep in mind that these plants will mature to a very large size. Some gardeners choose to keep them in pots until the size of the plant (and its spiky leaves) makes it more practical to plant it in a permanent location in the ground.

If you choose to plant Agave americana in a container, choose a large pot and soil that offers excellent drainage. A combination of soil materials, such as an even mixture of compost, potting soil, and gravel or sand, is a good blend. You could also use a pre-mixed blend of succulent potting soil.

Fortunately, century plants are relatively slow-growing. You likely will only need to repot the plant every other year or so. When it’s time to replant, wear protective gear like gloves, a long-sleeved shirt, and pants to protect your skin from sharp spines. Replace the potting soil with a fresh mixture and choose a larger pot that will allow for the continued growth of your century plant.

Overwintering

The century plant is not frost tolerant, so it must be brought indoors to survive winter weather outside of its growing zones. If you have cold but relatively dry winters, you can overwinter a mature agave plant by providing it with a measure of protection from the elements. Plant it in a location that is well-draining and sheltered from northern exposures. Another option is to situate the plant next to a large rock, which will radiate heat after the sun goes down. If overnight temperatures reach the lower limit of this plant’s tolerance, cover it with a cotton sheet for additional protection.

How to Get to Bloom

The most challenging part of getting a century plant to bloom is waiting for it to happen. In most cases, it will take 20 to 30 years before the plant sends up a single branched stalk with blossoms, reaching 20 feet or more in height. Fertilized or rapidly maturing plants might blossom in as little as ten years, but this is the exception rather than the rule. These plants only bloom once in their lifecycle, after which the plant dies.

After the century plant blooms, the leaves will collapse and the parent plant will die. However, because these plants are prolific producers of pups, a colony of offshoots will continue to thrive in the location.

Common Problems

The century plant is a healthy, vigorous plant that grows well when provided with the right growing conditions. However, it can face challenges in overly-moist conditions and gardeners must be vigilant in warding off the plant’s primary nemesis: the agave snout weevil.

• Wilting or discolored leaves

If the leaves of the century plant become squishy, wilted, or discolored, this is a likely indicator of the most common problem to affect century plants: root rot, which is caused by overly moist soil conditions due to excess rainfall or watering. If the plant is manageable in size to dig out of the ground, you can examine the roots and cut away any black, slimy parts. Treat the remaining roots with a copper fungicide. Replant it in a drier location or amend the soil to improve drainage, perhaps with pumice, gravel, or sand.

• Weak or foul-smelling plant

Typically, the large-growing century plant is steady and won’t easily be budged from side-to-side. However, if you notice that your plant is tilting or leaning or if a foul smell is coming from the plant, these are indications of an agave snout weevil infestation. These species of weevil feasts on large agave species, like the century plant. They weaken the plant by burrowing into the leaves to lay eggs.

Once hatched, the larvae feed on the plant’s tissue. Compounding the problem, bacteria enters the plant through the holes left by the weevil and the plant begins to decay, resulting in the foul smell. Once the visible signs of an agave snout weevil infestation are present, it’s often too late to save the plant. The best option is to protect century plants from weevils and other plants through a regular application of neem oil or other insecticide.

III. Uses and Benefits

• Ornamental uses

Agave americana is great for beds and borders, city gardens, coastal gardens, rock gardens, succulent gardens or Mediterranean gardens. Ideal as an accent plant in sunny borders or in decorative containers! Effective as hedges.

• Medicinal uses

Agave americana contains agavose, a sugar that is isomeric (similar) to sucrose (C12H22O11 ) but with reduced sweetening power, as well as agavasaponins and agavosides. It is used in traditional medicine to treat various ailments, and as a laxative, diuretic, and diaphoretic. However, a comprehensive review of research literature using systematic methods (scientific review) did not find sufficient data to support its effectiveness or safety. It is important to note that A. americana can cause severe allergic dermatitis.

• Culinary uses

Agave americana has various uses starting in pre-Columbian Mexico. If the flower stem is cut before flowering, a sweet liquid known as aguamiel (“lit. ’honey water’) can be collected from the plant’s hollowed heart. This liquid can be fermented to produce the alcoholic drink called pulque or octli used in pre-Columbian Mexico.

In the tequila-producing regions of Mexico, agaves are known as mezcales. Mezcal refers to the high-alcohol product obtained through fermented agave distillation, and A. americana is among the several Agave species used for this purpose. The specific mezcal known as tequila is produced from Agave tequilana, commonly referred to as “blue agave.” Mezcal comes in various types, some of which may be flavored with the intensely pungent mezcal worm.

It is important to note that mezcal and tequila, despite being produced from agave plants, differ from pulque in their sugar extraction techniques and classification as distilled spirits. In mezcal and tequila production, the sugars are obtained by heating the piñas (or hearts) of the plants in ovens, as opposed to collecting aguamiel from the cut stalk of the plant. Therefore, if pulque were to be distilled, it would not be classified as mezcal but rather as a distinct beverage.

Agaves are also found throughout Latin America and are used in similar ways. In Ecuador, the equivalent of pulque is known as guarango, which has recently been distilled as miske.

Agave nectar is marketed as a natural sweeteners with a low glycemic index, primarily due to its high fructose content.

• Other uses

Fibers

The leaves of A. americana yield fibers called pita, which are suitable for making ropes, nets, bags, sacks, matting, and coarse cloth. They are also used for leather embroidery in a technique known as piteado. Both pulque and maguey fiber played significant roles in the pre-Columbian economy of Mexico.

Heraldry

The plant holds heraldic significance and is featured in the coat of arms of Don Diego de Mendoza, a Native American governor of the village of Ajacuba, Hidalgo.

Art

Additionally, the Aztecs used the pulped leaves of A. americana to create paper. The fragments known as the Humboldt fragments were made using this technique.