In the past few years, the desire for succulents as houseplants has skyrocketed. Cacti, among many other succulents, have gone into mass production to provide for plant enthusiasts.
When talking about cacti, there are some inevitable concepts that have to be brought up such as CAM plants and the fact that cacti have no leaves.
As you grow your cacti collection, you may begin to be filled with questions, because the cacti world can be confusing.
After acquiring a few plants, you may ask things like, how fast do cactus grow? Or, how do I make my cactus grow faster?
Well, luckily, we can come together and begin to explore these questions and the cactus world!
Cactus Growth Stages
To talk about growth stages, let's first go over some biology to understand how these plants grow.
Cacti are CAM plants, which according to Arizona State University, stands for Crassulacean Acid Metabolism. With succulents living in a desert climate, they have come up with different ways to photosynthesize in order to adapt.
For CAM photosynthesis, plants need to conserve water (in this case, in their succulent leaves and stems), so they only open up their gas-exchanging cells, the stomata, at night. Once the CO2 is taken in and stored for the night, the plant moves onto the next stage of photosynthesis.
The acid part of the word CAM comes from the fact that CO2 is stored as an acid throughout the night. When the sun rises, the plant closes its stomata and uses CO2 as part of the Calvin cycle.
The University of California, Berkeley explains CAM plants and other ways of photosynthesis and photorespiration here.
Secondly, it is important to mention the anatomy of the cacti, which all primarily are part of the Cactaceae family. The green fleshy structure of the cactus is botanically the stem, while the spines, or armature of the plant, are considered modified leaves.
Cacti do the majority of their photosynthesis by using their stems. Plus, the top growing point of the cactus is called a cephalium.
If you are talking about growing cactus from seed, you may want to buckle in for a long-term investment.
Cacti seeds are very tiny, so that alone can tell you how difficult it may be to even germinate. Like most seeds, cacti seeds like warm and moist conditions to germinate. Be sure there is high humidity during the germination process as well.
After taking care of the seeds for a few weeks, and sometimes months, they will finally germinate! Although, you may need a magnifying glass to see them.
In about a year your cactus, in most cases, will be maybe the size of dice. They take a long time to grow and to be a commercial grower, this would be a five-to-ten-year investment.
If you grow a cactus from seed, and if in a few years it might be able to flower, you can initiate its flowering stages by leaving it in dark conditions for a month and a half and then expose it to a good watering and some sunlight.
After the plant flowers or you initiate flowering, if you want to develop fruit, most of the time you have to pollinate the plant with a separate cactus because most cacti flowers are sterile.
Cactus Growth Rate
Again, cacti generally grow very slow with most only growing a few centimeters per year. A lot of this has to do with their native climate and will to survive with a lack of water.
Some cacti grow a little faster, like Austrocylindropuntia subulata, but overall, you will still find that cacti grow slow because of how they are built and what climate they are built for.
Why Is My Cactus Growing So Fast?
If you're asking yourself why your cactus growth won’t slow down, this could be because you may have one of the faster-growing species.
Along with this, you could also be fertilizing a good amount, have the right sun and water conditions, and have the appropriate pot and/or soil for the plant.
Why Do Cactus Grow So Slowly?
With modified leaves (spines) serving the purpose of an armature, all the cacti really have to photosynthesize are their green fleshy stems.
This leaves the plant not able to photosynthesize as quickly as other plants. Also, again, being in a hot, water-lacking climate stops them from being able to grow rapidly.
How To Make Cactus Grow Faster
If you are looking at your cacti plant week after week and are not seeing any growth, there may be a few steps you could take in order for it to possibly grow faster.
Fertilizing is almost always an option but be sure that you are feeding your plant the recommended amount at the recommended time. The last thing you want is to burn your cactus by adding too much salt in the soil (from over-fertilizing).
For a good cactus fertilizer, you could find one here.
Secondly, you could make sure that your cactus has the correct soil that it will thrive in. A good sandy succulent soil mix would work well and can be purchased here, online.
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Beware of the perching effect when building your succulent soil. Most people recommend that you put rocks on the bottom of the pot or on top of the soil – this can cause chaos.
The rocks make an uneven soil media that can have negative effects on draining.
Minda Daughtry, from N.C. Cooperative Extension goes more in-depth about this perching effect here.
So, with the correct fertilization, soil, and water management, a cactus has the potential to grow faster.
Also putting your plants in clay or terracotta pots can help them dry out evenly. With adding the correct sunlight and warm consistent temperature with all this, you very may well be able to make your cactus grow faster!
I often wonder why people recommend succulents and cacti to people as starter plants, because they sure do require specified care, and take a lot of patience.
This being said, cacti are slow growers because of their native habitats, for they have to conserve water, use CAM photosynthesis, and they don't photosynthesize with leaves.
With the right conditions like proper fertilizer, soil, pots, sun, and water management, there is a good chance you can increase your cacti’s growth rate.
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So, when you ask yourself, how fast do cactus grow? Remember that it is not very fast, but there are steps you can take to help them be the healthiest, fastest-growing plants that they can be!