How To Tell How Old A Cactus Is (3 Methods)

Cactuses can live for hundreds, and even thousands, of years in their natural habitat. If you want to learn how to tell how old a cactus is then you’re in the right place

Determining the age of the cactus is a fun exercise, but it is pretty much impossible to know the exact age of your cactus. You can get a general idea of the cactuses’ age using a few methods, including measuring the height or counting the number of areolas or arms.

Cacti Don’t Have Rings 

Trees have rings, which are a reliable way to determine how old they are. Cacti, on the other hand, do not have rings. They are not made from a fibrous material like wood. 

The bulk of a cactus is water-storing tissues. In the center are vascular tissues that transport water and nutrients throughout the plant. The cactus uses the water-storing tissues to store water, of course. A cactus can be 90% water. 

Cacti are constructed this way to survive in low water conditions. They can survive long periods of drought because they store water for later use. 

Most trees have growth rings because the growth speed changes due to changing conditions. These include rainy and dry seasons and temperature changes associated with the changing of seasons.

After the summer solstice, the longer nights tell the tree to reduce the resources used to grow taller, and use them to grow the trunk. They grow less when growing conditions aren’t ideal, including periods of drought and low temperatures. 

The cell wall thickness changes when the growth rate changes, which is what creates growth rings. 

Types of Cacti 

Cacti are a type of succulent. All cacti are succulents, but all succulents aren’t cacti. Cacti are cacti because they have areolas, which are growths that have spines or thorns protruding from them. 

The basic types of cacti are barrel, columnar or spherical, and pancake. There are at least 300 different genus of cacti, and 2,000 species of cactus. However, they can all be grouped into one of these three categories. 

3 Ways To Tell How Old A Cactus Is

Here are 3 methods to tell how old your cactus is.

1. Measuring the Cactus 

The most well-known way of measuring your cacti’s age is to measure its height. There are a few problems with this method, however. 

There are over 2,000 species of cactus. Each will have its own growth rate. Some will grow much faster or slower than others. For example, the Golden Barrel cactus, or Echinocactus platyacanthus, which is over 100 years old can grow up to 8.2 feet tall. A Saguaro cactus, or Carnegiea gigiantea, of the same age can grow to 15-16 feet tall. 

Still, measuring your cactus can give you a general idea of its age. For an accurate estimate of the cacti’s age, you would need to measure its growth over a period of at least 2 to 3 years. You could then use that to determine how old it is. 

However, you probably aren’t that invested in getting the exact age of your cactus. The generally accepted growth rate for a cactus is one inch every 10 years. 

So, if your cactus is 6 inches tall, it is likely about 60 years old. However, some fast-growing species can grow up to 8 inches in a year, so this method certainly leaves something to be desired. 

A green and white cactus in a small white pot

Growing Conditions 

The other issue with using the height of your cactus to determine its age is that how fast your cactus grows will also depend on growing conditions. In times of drought, a cactus will stop growing. When the weather improves, it will begin growing again. 

Generally, species that grow in very dry conditions naturally will grow much slower. The Pachycereus pringlei , for example, is very slow growing. It’s native to the Sonoran desert, which is very dry. 

However, species that grow in locations with plenty of precipitation, including Opuntias and prickly pears, will grow very quickly. Other cacti, like the Christmas cactus, grow moderately fast.

2. Number of Areolas

The number of areolas is another way to determine a cacti’s age. The areola is a structure unique to cacti. It’s a modified branch or shoot. In appearance, it looks like a bump on the skin of the cactus. Spines, thorns, or hairs will radiate from the areola.

Thorns that are less than a year old are typically red. As they age, they turn brown. The areolas at the top will be younger than those at the bottom. 

More areolas typically indicate an older cactus, but there’s no exact relation between areolas and age to determine exactly how old the cactus is. 

3. Number of Arms 

Columnar types of cacti will grow arms branching off the main stem. Other types of cacti do not grow arms. 

Of course, the rate at which arms grow also varies based on the species. A Saguaro must be at least 70 years old to begin growing an arm. If it has a fully grown arm, it’s at least 100 years old. If it has more than one arm and is producing flowers, it is at least 150 years old. 

On the other hand, the golden barrel cacti, will never grow arms, because it’s a barrel type. 

How Large Can Cacti Get? 

The tallest cactus in the world is a Saguro in the Sonoran desert. It is over 78 feet tall. Its age is estimated between hundreds or even thousands of years. 

Cacti will not die of old age as people, and many plants, do. The average lifespan is believed to be 200 to 300 years in the wild. Indoors, the cacti will typically live about 10 years if it’s well cared for. 

In Summary

You won’t be able to pin down the exact age of the cactus, but you can get a general idea. The simplest way to do this is to measure your cactus, assuming that it grows 1 inch every 10 years. Of course, some grow much faster. 

Photo of author

About Me

Hi, I'm Joe! I'm the head of SEO and content management at Bloom and Bumble. I'm a huge plant lover and over the years my home has become more like an indoor rainforest. It has taken a lot of trial and error to keep my plants healthy and so I'm here to share my knowledge to the rest of the world.

Leave a Comment