How To Tell An Aging Cactus? The 8 Signs

Have you seen those pictures of gigantic cacti growing in Phoenix, Arizona desert lands? They have been growing there for a long time, nurtured by nature. It got us thinking, how old can cacti get?

The age of the cacti cannot be measured perfectly as there are varying aspects that affect the evaluation. However, the most important sign of an aging cactus that can help to quantify its age are:

1. Natural Corking,
2. Shrinking Base,
3. Array of Flowers,
4. Numerous Solid Spines,
5. Shedding Wools/ Hairs,
6. Rib Formation,
7. Cephalium/ Crown Formation, and
8. Relatively Large Size.

Is it possible to tell the age of a cactus? How can I tell that a cactus is already old? Do you have these thoughts rolling in your mind too? Read further to put an end to your questions.

How To Determine The Age Of A Cactus?

There is no method that allows to exactly defines the age of a cactus by mere observation. Nonetheless, the cactus height is an empirical good estimation of its age. The spines and ribs are also used to make an approximate count of the years a cactus lived.

According to Arizona- Sonora Desert Museum, an average desert cactus grows 1 inch every 10 years.

Take note that this is just a rough estimation, as the exact age of the cactus is impossible to find out. Spines also indicate the growth of the cactus. Old spines record the old-growth, while young new spines indicate new growth.

The number of ribs was also used to measure the age of a cactus. Counting the ribs of a juvenile cactus and comparing them to the ribs of the mature plant can be a useful approach.

However, these are all guestimation, so the age of a desert cactus is unknown. Their ability to become dormant at some point is another factor that can affect age calculation.

Unless you are the one who nurtured the cactus from seeds to maturity, then that’s the only way you can tell the exact age of the cactus. The height, ribs, and spines of a cultivated cactus are not viable in telling their age.

How To Tell If Your Cactus is Old? The 8 Signs

The 8 Signs of an aging cactus are:

1. Natural Corking,
2. Shrinking Base,
3. Array of Flowers,
4. Numerous Solid Spines,
5. Shedding Wools/ Hairs,
6. Rib Formation,
7. Cephalium/ Crown Formation, and
8. Relatively Large Size.

In general, cacti can live pretty long enough. Keep them in a hospitable condition, and you will see your cactus thrive and live for several years and even decades! You can tell that cacti have lived for many years as they will start to show signs of aging with time.

Here are the signs of an old cactus:

1- Natural Corking

As the cactus mature, it is natural for them to develop a hard, brown, and wood-like tissue from the base of the plant just above the potting medium. It is referred to as corking in biology, and it is a normal response of a cactus as it grows.

Corking is part of the aging process where the stem of the cactus turns brown from the bottom up and gets hardened, just like a tree. Although it is not an appealing sight for a cactus, it is vital as the plant matures, especially for the columnar types. Corking on the cactus base prevents the whole plant from toppling down as it becomes top-heavy.

Do not confuse natural corking with fungus and sunburn. The occurrence might be similar, brown, and firm tissues, but corking normally starts from the base going up. In contrast, fungus and sunburn appear like patches on any segment of the stem.

2- Shrinking Base

Due to the weight of the heavy aging cactus, the base will become recessed or shrunk at some part. Shrinking is usually accompanied by corking.

As the cactus grow taller and larger, the heavier it will become. Therefore, the weight of the entire plant will be on the stem pushing it down to the base. Shrinking is more apparent in Parodia, Echinopsis, and other cylindrical cactus species. A shrinking base of an old cactus is rigid and not squishy.

Watch out if your old cactus shrinks and has a soft stem. Shriveling might be due to aging, but a soft or mushy base might indicate another health problem triggered by overwatering or underwatering.

3- Array of Flowers

Although there are cactus that can shoot flowers even at a younger age, some genera take 2 to 3 decades before the appearance of their first bloom.

You can tell that the cactus is mature when it never fails to give off flowers every season. However, keep in mind that despite its age, a cactus will not still produce flowers if the condition is not right.

4- Numerous Solid Spines

An aging cactus has more solid and prominent spines compared to younger ones. The color of the spines is darker with mature cactus.

According to Muaseth Research from the University of Texas, the mature spines are primarily dead cells with its base as the only part with living cells. Mature spines are usually found on the bottom part of the cactus stem, rigid and dull-colored.

Matures spines of an aging cactus will not grow back if removed or damaged because they become inert over time. New spines will only grow on the part where new areoles are formed, which is on the stem’s top segment.

As cacti age, spines become denser and longer, such as in Echinocactus and Ferocactus. The compacted long spines help reduce the surface area of the cactus, thus protecting the mature plant from losing moisture quickly.

5- Shedding Wools/Hairs

The hairs and wools of some cacti species will gradually become less as they mature. The stem will shed these covering from the bottom edge, leaving only the top part to remain fuzzy.

Cacti such as Cephalocereus and Oreocereus have hairs around its stem. It serves as their protection from the blazing sun and biting frost. Mature specimens of these cacti will tend to lose some of their hair along the base. However, the top portion remains hairy and fuzzy as the cactus continues to grow.

6- Rib Formation

Cactus ribs start to multiply as they age. It is natural for older cactus to have more ribs. Indeed, ribs allow the stem of an aging cactus to expand as it takes in water and shrinks during drought.

The number of ribs is sometimes the basis of some biologists to estimate the age of a cactus. The larger the number of ribs, the older the cactus. As the stem of the cactus ages, the ribs continue to grow to form more pleats around the cactus stem.

7- Cephalium/ Crown Formation

Several genera such as Melocactus and Backebergia militaris grow a cephalium as they age, while Golden Barrel cactus develop a crown of spines and wools. These physical changes take place once the plant is old enough.

Adult cactus that form a cephalium differs significantly from their juvenile phase that many people would think it is grafted. A Melocactus starts to develop a cephalium after 5 to 6 years, that wools and tiny spines begin to form from the center, growing as the plant matures.

The crown of a Golden Barrel Cactus is where the flowers, fruits, and seeds develop. It is made up of short spines and a large mass of wool. When a mature Golden Barrel cactus starts to develop a crown, it can produce flowers.

8- Relatively Large Size

Some species grow taller and bigger with arms or clumping offsets, while others grow more pads or cladodes as they mature.

An average adult cactus measures 5 times more than it was still a juvenile plant. Species such Parodia, echinocactus, and mammillaria become clumping cactus as they get older. While a matured Opuntia and thanksgiving cactus grow more pads and cladodes over the years.

The columnar cactus gets taller, developing arms when they reach a certain age of maturity. However, the barrel cactus such as Golden Barrel Cactus, Ferocactus, and Melocactus get bigger as they develop more spines and ribs.

How Long Does Cactus Last?

The lifespan of a cactus is just an estimation of those scientists working in that field based on the plant’s facts, the environmental conditions, and its origin. There is no specific method in determining the exact age of the cactus growing in the desert.

The table below shows the results of the extensive studies of several botanists exploring different cacti from the world’s deserts.

CACTUS NAME	LIFESPAN	SIZE	SIGNS OF AGING
Saguaro Cactus	300 years	78 ft tall	Solid hard spines, Multiple ribs, Clumping flowers, Corking, Shrinking
Golden Barrel Cactus	50-100 years	3ft tall  3 ft wide	Numerous spines, Coroa Formation, Rich blooms, Several Ribs, Corking, Shrinking base
Prickly Pear Opuntia	20 years	8 feet tall  15 ft wide	Multiple Cladodes/Pads, Hard Spines, Flowers and fruits, Shrinking stem, Corking/ wood-like
Melocactus	30-60 years	3ft tall 1ft across	Cephalium formation, Strong, Curved spines, Corking
Cephalocereus senilis	20-50 years	49 ft tall 9 feet  across	Grow taller, Shedding of hair, Flowers, Solid spines
Moon Cactus	5 years	Scion is 2-4 inches across	Multiple offsets, Flowering
Christmas Cactus	20 years	Stems are 2-3 feet long	Multiple phylloclades, Corking, Bursting with flowers, Long stem segments

Do Cacti Show Age Differently?

Every cactus has a different aging process. Some grow cladodes or pads while others become taller, extending many arms. As other cactus grow extremely large with age, some cacti remain small even in maturity.

Below are some examples of cacti showing how they look like when they are old.

Gymnocalycium mihanovichii ‘Moon Cactus’

Moon cactus has a short lifespan only. With proper care and the right condition, the moon cactus can reach up to 5 years or more if regrafted to a healthier rootstock. The height of the moon cactus depends on the rootstock, usually a foot high.

As the moon cactus matures, the head part remains small up to 2 inches or 4 inches if it produces many offsets around its spherical body. These offsets can be grafted for propagation to continue the lifecycle of the mother plant.

Mature moon cactus sometimes demonstrate shrinking from the junction between the scion and the rootstock as the top head gets heavy with offsets. When a moon cactus reaches maturity, flowers will begin to form.

Echinocactus grusonii ‘Golden Barrel Cactus’

The spherical Golden Barrel cactus has an approximate lifespan of 50- 60 years and can grow large, roughly 3 feet tall, and 3 feet wide when fully matured. They are fast growers in their early years but slows down upon approaching the adult phase as they put more energy into producing flowers.

Corking is the usual sign of a grown-up golden barrel cactus. They form a corona on their top as they get old, where flowers, fruits, and seeds develop. Only mature golden barrel cactus produces blooms. Offsets do not usually happen, but reproduction via seeds is common.

As the golden barrel age, their spines become as hard as wood, and they develop multiple ribs for about 20-40 until full maturity.

Schlumbergera truncata ‘Thanksgiving Cactus’

The epiphytic schlumbergera cactus, commonly called crab cactus or thanksgiving cactus, has fleshy segments or phylloclades joined together to form a cascading arrangement of stems.

The primary stem of the cactus demonstrates a hard, thick, and brown stem beneath the series of trailing green stems. You can see that the corking of the stem supports the plant as it develops more segments. The adult thanksgiving cactus is capable of exploding flower bouquets in the fall.

Schlumbergera species are known as zygocactus because of their zygomorphic flowers. With proper care, they can live up to 20 years.

How Long Do Indoor Cactus Live?

The lifespan of an indoor cactus solely depends on the care and cultivation method the grower is providing. As long as the ideal growth requirement is met, the cactus will surely thrive for several years and even decades.

Either you have your cactus outdoor or indoor, their longevity will be determined by the way you grow them. Provide them the proper growing medium, watering habit, sunlight exposure, and nutrition and your cactus will have a longer life.

Takeaways

• There is no correct method of telling the age of a cactus.
• An old cactus can have a natural corking, shrinking base, the explosion of flowers, and numerous solid spines. Some mature cactus get relatively large and shed their wools or hairs. Most barrel cactus develop more ribs and form a cephalium or crown when they reach maturity.
• The schlumbergera species is one of the indoor cactus that can grow up to 20 years given proper cultivation.

Sources

• “Cactaceae,” Arizona-Sonora Desert Museum Organization
• “Cactus Spines,” by Mauseth J. D., University of Texas
• “Desert Giants: Life and Death Among the Saguaros,” by Lori Stiles, University of Arizona
• “Echinocactus Grusonii,” University of Vermont
• “Prickly Pear Cactus,” Arizona-Sonora Desert Museum Organization
• “Cephalia: Juvenile/Adult Phase Change in Cacti,” University Of Texas
• “Cephalocereus senilis ,” Asian University of Bangladesh
• “Scientists study puncture performance of cactus spines,” University of Illinois

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