If you own a cactus, then you'll be keen to know how fast it will grow and how large it will get with time. It's good to know this so you can plan where to put your cactus and decide what plants to grow alongside it. So, how fast do cactus grow?
Most cactus grow slowly, sprouting to the size of a large marble after 6-12 months, and to a few centimeters in height after 2-3 years, depending on the species. After this, most cacti grow 1-3 cm in height per year. There are a few notable exceptions that can grow up to 15 centimeters or more in height per year.
- Echinocactus such as the Golden Barrel Cactus grow 1-2 cm per year in height on average.
- Ferrocactus species grow approximately 2-3 cm in height per year on average
- The Saguaro Cactus (Carnegiea gigantea) grows 2-15 cm per year, depending on the growth stage, and can reach heights of 75 feet.
Growing your cactus to full size will indeed be a waiting game for most species. In this article, we’ll give you a growth timetable as well as tips that may be able to speed up growth. Be sure to read on!
Why Do Cacti Grow So Slowly?
To understand why cacti grow slowly, there are two main factors to consider.
The first is that cacti are highly adapted for survival, in climates with unpredictable and infrequent rainfall. As a result, they focus their energy on survival, rather than rapid growth. Read more about the amazing ways that cacti are adapted for survival.
A cactus may have to survive many periods of drought and extreme heat. Without prioritizing survival, cacti would die due to the harsh climate before having the opportunity to reproduce.
It is important to mention that not all cacti live in arid climates. There is a subset, called jungle cacti, which have different adaptations to those we commonly associate with desert cacti.
The second factor is leaves, or rather the lack of them. Most plants and flowers have leaves. These may be various sizes, shapes, and thicknesses, but they are there. Leaves contain a high concentration of chlorophyll, which is the chemical that converts sunlight into energy for the plant to use. With plenty of energy production capacity, most plants are able to grow quickly and strongly.
Cacti have no leaves or branches. Instead they have areoles and spines, which have no role in energy production for the plant. Leaves are less suitable for a hot, desert environment because they cause plants to lose too much water too quickly.
As a result, cacti have much less green tissue compared to other plants, which retards their growing abilities, according to the University of Nevada Cooperative Extension.
How Fast Do Cactus Grow?
Let’s begin by discussing the various growth stages for most cactus species and how long they take. These milestones are assuming the cactus is in an environment that’s not too cold or too warm, the plant gets the right amount of sunlight, and it’s watered and otherwise tended to when needed.
…In A Month?
Cacti, like many plants and flowers, begin their lives as seeds. It can take between several weeks and several months for the germination process to occur in seedlings, so don’t expect much if any growth in the early days.
If you’re lucky, you might notice the spines of the cactus will begin to grow within a month. That said, not all species of cacti have spines. What you’ll be looking for in those species is seedlings popping up from the dirt.
If you don’t see anything growing after a month, be it spines or seedlings, then keep waiting. In many instances, growth of this level can take two or three months to occur. With a cactus, waiting is key.
During this growth phase, it’s important to take off any coverings you have over the cactus during the day. This lets it get more ventilation. You’ll also want to water the cactus every time the soil gets dry. We’ll touch more on both these points later.
…In Six Months?
As you continue to care for your cactus, it will grow, but still not very fast. Once six months have passed, your cactus may be no larger than a slightly big marble. Compared to many other plants and flowers, this may seem like an abnormally slow growth rate, which might make you nervous. In a cactus, this slow growth is typical, so there’s no need to panic.
…In A Year?
It’s also not abnormal if your cactus is still marble-sized after 12 months. Upon achieving that milestone, no matter how long it takes, your cactus should be moved from a propagation tray to a separate pot. Move them to a bigger container so their growth can continue.
…In 30 Years?
Cactus growth may vary over the years depending on the cactus species you have. For instance, the Saguaro cactus, which comes from Arizona’s Sonoran Desert, can grow quite tall. Over its lifespan, a Saguaro can grow as tall as 75 feet.
During the lengthy growth process, Saguaro cacti can sprout their own flowers. This will typically happen within 30 to 35 years. We weren’t kidding when we said growing a cactus is a waiting game!
What Can Impede Growth Even More?
While it’s true that cacti are generally slow growing, there are some things you may be doing that can make them grow even more slowly. Here are some trouble areas to be aware of and correct.
Leaving It In A Container That’s Too Small
When your cactus becomes the size of a big marble, it needs a new home. Not doing this is bad news, as your cactus needs nutrients to survive and grow. A container that’s too small limits how many nutrients it can get. That will definitely cap its growth potential if the cactus doesn’t die.
Remember that the cactus must be moved more than once as it continues to grow, so you’ll rehome it several times.
Overstressing The Cactus
Just like we people go through an exhaustive process when moving our homes, so do cacti. They need time to recoup once they arrive in their new container. Keep them away from direct sunlight for a few days. This lets the cactus roots latch to the new home. Then, put the cactus back in the sun for a while each day, increasing the time incrementally.
Overwatering
You can’t really underwater cacti unless you never water them at all. They require much less water than most plants and flowers due to their native desert environment. You may be able to go a month before you have to water the cactus again depending on its age and species. I've got a useful article about how to water cacti if you want to learn more.
Overwatering will impede growth if it doesn’t kill the cactus outright. It can be hard to tell if you’re overwatering your cactus, especially if this is your first one. That’s because, within the first few weeks or months, the cactus will be asymptomatic even if it’s getting too much water. In some instances, the cactus grows more or gets bigger. That gives you the impression that you’re doing everything right.
Very quickly, it all starts to go wrong. The roots of a cactus cannot get too much water or they’ll rot and then die. Your cactus may look like it’s doing great, but behind the scenes, it’s slowly dying on you.
A few roots dying may not be a big deal, but the more dead roots, the higher the chances of your cactus not surviving. You may notice the color of your cactus is different as it begins dying. It may also be soft to the touch. The whole plant will die from here, and unfortunately, there’s no way to turn it around.
Once you get more experience raising cacti, you’ll learn to recognize that them growing fast and large is often a bad sign.
Keeping Your Cactus Covered For Too Long
It's generally best to cover cactus seedlings during the germination and early growth phase. This will increase humidity and keep the seedlings warm, improving their chances of successfully germinating.
However, failing to remove the cover at the right time can harm your cactus, especially if it’s just starting to grow. The seedlings need ventilation. A lack of ventilation can stunt growth and possibly even kill the cactus.
How To Speed Up Cactus Growth
If you avoided the above pitfalls and your cactus still isn’t growing quickly enough for your liking, you have a few options to speed up the process. Here are our suggestions:
- Always make sure your cactus has a container that’s more spacious than what it requires. This way, it has more than enough room to grow. You’ll also have to move the cactus less often, which reduces stress. That keeps the growing process going slowly yet surely.
- Use a well draining potting mix. A mix of potting soil, coarse sand and perlite is ideal. This will reduce the risk of overwatering, which can significantly damage the plant and slow growth. As you remember, too much moisture is a cactus root killer. Read my article about choosing the perfect soil for your cacti.
- Sunny environments are ideal for cactus growth. Find the brightest area and put your cactus there. Every week, turn the cactus so the whole plant gets sunlight.
- Maintain the right temperature for cactus survival. Indoor cacti will thrive in temperatures of between 65 and 80 degrees Fahrenheit. Just be careful about excess heat and direct sunlight if your cacti and kept in a south facing window. For outdoor cacti, a wintertime temperature of between 45 and 55 degrees Fahrenheit is fine. Once summer hits, the threshold increases to 65 degrees on the low end and 85 degrees on the high end.
- Throughout the spring and summer, use a succulent fertilizer on your cactus. This should be a liquid, low-nitrogen product.
If you want to learn more about growing and caring for cacti, there is one great book that I recommend in my resources section.
You may also be interested in some of my other articles.
