How To Tell How Old A Cactus Is? Fully Explained!

The best way to know a cactus age is to observe the height and size, precipitation received by the cactus, number of areoles and arms.

Have you ever wondered how cacti can survive in the desert? Or, how old are they? Considering the dry and hot climate, you may be shocked that cacti can live for hundreds of years! And in fact, the oldest saguaro cactus was recorded to have lived for up to 300 years in the Sonoran desert before it died in 1990. Not only that, but it also reached 40 feet tall with 52 arms. But how to tell how old a cactus is? How can they know that it was the most gigantic and oldest cactus ever grown in the world?

And for that reason, we will explain in detail how to determine the age of a cactus and the calculation method to estimate it accurately. But before that, it is better to know the life stages of these desert plants. So, without further ado, let’s dive into the cactus world!

What are the stages of a cactus?

Like other plants, the cactus has several phases of life. Hence, this section will specifically discuss the life stages a cactus goes through up until they mature. There are five main stages of cactus growth: germination, vegetative growth, flowering, pollination, and fruiting. Keep reading and pay attention to the details, so you don’t miss a thing!

1. Germination

The life of a cactus begins with germination. This plant has dormant seeds that will be seedlings when they meet their preferable growing conditions. Some of them are changes in soil conditions, temperature, humidity, and light intensity.

It requires porous and sandy soil under bright sunlight to thrive. With an adequate water supply, such soil types and conditions allow oxygen to pass through the coating, stimulating germination. The water helps the coating break, releasing its food reserves to grow and develop in the germination process.

Although it loves sun exposure, the temperature favored by the seeds to start germination is around 25°C with relatively low humidity, ranging between 40-60%. Therefore, maintaining these two factors is crucial to ensure you have healthy seedlings to continue the vegetative growth process.

how to tell how old a cactus is
Cactus in Garden

2. Vegetative Growth

Vegetative growth is the stage after seedlings of the cactus seeds or leaf cuttings. In this phase, the shape of the mature cactus plant will begin to appear, according to the species. Some of them take months through this stage. Meanwhile, others may have to wait for years before they become mature cacti. For example, prickly pear cactus need around 2-3 years before flowering.

3. Flowering

You may not think that cacti can flower. They can produce flowers well when the air temperature reaches 50°F with low humidity (40-60%). Given those growing conditions, they fully bloom in the summer. During this time, they will need water to thrive until the end of the season. But please pay attention to the amount as overwatering triggers root rot and fungal diseases because of the soggy soil and eventually kills the plant. Unfortunately, the flowers will only last a few days to two weeks.

4. Pollination

Even though this stage is essential for producing fruits, natural pollination in cacti is tricky since the flowers only bloom briefly. However, it is still possible to help them get pollinated. The best way is to ensure that there are two or more cacti close to each other and bloom. Then, let the wind blow or the rain drops and bring the pollen to stick to the pistil.

5. Fruiting

If you manage to stimulate pollination in your cacti, you will notice the fruit formation on your plant. Initially, it grows small, like berries on the tips of the stems, before growing big, as on prickly pears. Some species grow the fruits slowly, around two inches or so in three years. After that, it will be an inch per year. However, it always depends on the varieties of your cacti. The golden barrel cactus, for example, grows only half an inch per year. In contrast, the saguaro cactus can reach around seven inches.

How to determine the age of cactus plants?

Now, we are heading to our main topic: “how to tell how old a cactus is?” Since cacti do not have growth rings, it is so hard to determine their age. The best way to know their age is to observe the height and size, precipitation received by the cactus, number of areoles, and arms. Stay with us, and kindly read the details below.

how to tell how old a cactus is
Cactus Plants

1. Height And Size

The age and size relation to knowing the cactus age only applies to the saguaro cactus, as there is still no research supporting other cactus species. This may be because the saguaro is the oldest type of cactus on earth.

In general, researchers will observe the growth of this cactus from year to year for several years, then measure its size. Then, the results will be made like a table explaining the differences in the size of the cactus each year. Furthermore, this research shows that the cactus (mainly the saguaro cactus) grows about 7-8 inches tall yearly.

2. Precipitation Received

In addition to the height and size, precipitation also affects the growth of the cactus, which will eventually help researchers determine its age. Cacti growing in more humid areas tend to grow faster than those thriving in the dry habitat. An example is the Mexican Giant Cactus grows slower than Prickly Pears. It is because its habitat is arid areas on the western coast of Sonora, while the pears are in non-desert regions of North America.

3. Numbers of Areoles And Arms

The area where the flowers, fruits, arms, and thorns grow is called the areola. If you notice red-colored thorns, meaning that they are young ones. Another thing to observe on the young thorns is the column. The lower you go, the older the thorns are, and vice versa.

Meanwhile, the numbers of arms only apply to several cacti, including saguaro. If this cactus begins to grow arms, then they are approximately 70 years old. And for the fully grown arm, the cactus is probably 100 years old!

How to calculate the age of a cactus?

Cactus Growing
Cactus Growing

Despite not having a precise method to determine the cactus age, you can try to calculate it by yourself using the following steps:

  • Prepare a measuring tape in inches and the cactus plant you have.
  • Measure it vertically from top to bottom with the tape. Be careful of the thorns!
  • Then, take note of the height and divide it by ten because the cactus usually grows an inch per 10 years.

So, don’t worry if your cacti seem stuck with the same height as it grows super slow. The most important thing is to keep them healthy by providing proper care.

How long does a cactus take to mature?

Growing cacti does require extra patience because they grow very slowly. Most cacti grow an inch per year. Thus, imagine how long it will take them to grow tall like those in the desert.

They take 6-12 months from germination to grow until they resemble a large marble. Then, they will take another 2-3 years to develop a few centimeters until they become mature cacti. Then, it will steadily grow an inch per year.

However, the exception applies to several cacti below:

  • The saguaro cactus can grow 7-15 cm or 2-6 inches per year. No wonder the oldest and tallest cactus ever recorded was from this species, reaching about 60 feet tall!
  • Golden Barrel Cactus is another exception, growing 1-2 inches per year.
  • Ferocactus species commonly grow approximately 2-3 inches per year, slightly faster than the golden barrel.

Why does a cactus not have growth rings?

While most trees have growth rings, cactus does not develop one. Why? It is because the xylem and phloem (the vascular tissues) in the center are surrounded by the tissues that store water. In addition, some argue that it is related to the dry habitat where they grow.

how to tell how old a cactus is
Cactus not Have Growth Rings

The rings are generally formed due to changes in growth speed. Typically, this growth is influenced by environmental conditions (rain or dry seasons), which cacti do not experience in their arid habitat.

Furthermore, plants and trees generally like moist conditions with more water than dry, which will encourage their growth. In contrast, their growth will slow down when they face stressful situations, such as extreme drought or cold.

Can a cactus die of old age?

Unlike other plants or trees, cacti do not die as they age. Usually, cactus common issue that leads them to death is improper treatment, which is not under the growing environment. Some of them are too much water which makes the roots rot. This issue will lead to another serious problem when the root triggers fungal growth, causing the infection that can spread throughout the plant.

In addition to root rot and fungal infection, frozen damage may threaten your cactus. You will see black or yellow color appear on the affected parts before they start to dry and crisp. Luckily, they can recover if the damage is not too severe.

Excessive sun exposure can also leave the epidermis injured and die, leaving yellow marks and permanent scars that will never recover. Even though it does not make them die immediately, the injury will make the appearance less attractive.

Is the arm of a cactus related to age?

The answer to this question varies as people still debate about it. Some people believe that cactus arms are unrelated and cannot be used as a benchmark for estimating their age. Meanwhile, others argue that the arms can be used to know the age. One example is the saguaro cactus, in which the growth of these arms is one way to assess its age. If they have full arms, the cactus is about 100 years old.

Cactus
Cactus

So, generally speaking, the presence or absence of arms is not a determinant of age in most cacti. It only applies to some species, including the saguaro, for which there has been research. To this day, there is no specific way to determine age because cacti do not grow rings, usually used as a critical element in determining a tree’s age.

Conclusion

To sum up, there is no specific method to determine the age of a cactus as it does not have rings on its stems. However, you can observe the height, size, precipitation received, and numbers of areoles and arms to help you have an estimation.


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FAQ (Frequently Asked Questions)

How long can a cactus live?

The lifespan of a cactus depends on its habitat. If they grow in natural habitats, such as deserts, cactus plants can live up to 300 years. However, potted cacti will only last for about ten years, especially if you keep them indoors. This period may be shorter for cactus species that have delicate structures.

How long does it take for a cactus to grow full size?

Generally, the cactus plant requires around 6-12 months to grow from sprouting to its large size. Then, it will increase its height by a few centimeters in 2-3 years. Nonetheless, it highly depends on the cactus species. Some can grow extremely slowly, like the saguaro cactus. This cactus needs 50-75 years to only grow an arm!

How long can a potted cactus live?

While in their natural habitat, cacti can live for hundreds of years (around 300 years!), potted cactus and indoor cactus can only survive up to 10 years at max. If you want to try growing them for a long period, the saguaro cactus is your best bet! It is a super slow-growing cactus that needs 40 years to flower in its native habitat.

How old is tall cactus?

The taller they are, the older they are. There are several stages for the cactus plant to reach certain heights. When they measure about 6.5 feet, the age of the cactus is about 75 years. Meanwhile, cacti with a height of 15-16 feet are generally around 95-100 years old. In addition, those with a height of over 70 feet are probably over 150 years old! What an interesting fact!

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