When I first got asked this question I was a little confused because it was completely normal for me that cacti bloom. So I started to dig deeper and eventually I started understanding why some people are a little confused and rightfully ask why cacti even produce flowers.
Cacti have flowers because, like every living being in this world, they want to reproduce. Only that Cacti can reproduce asexually and sexually. Asexual reproduction is done by producing offshoots (also called “pups) near or on top of the mother plant. These pups are clones of the Cactus. And Sexual Reproduction is done through blossoms and pollination.
Cacti are plants that are growing in very harsh environments so it was very important for the cactus plant to find multiple ways to reproduce.
Resources in the dessert are sparse so cacti needed a plan b when it comes to reproduction. If they don´t have enough strength or resources to produce flowers or no pollinator is around to pollinate the cacti then the cactus needed a way to reproduce asexually.
The cacti can form little “clones” of themselves that are pretty much identical to the mother plant in every way. This will ensure that the plant survives but it does not help the plant to evolve or adapt to the changing environment around it.
Evolution can only be achieved by sexual reproduction. And that is done (in the plant world anyway) by forming blossoms and getting pollinated by a pollinator, like a bee or other similar insects.
This way genetic material is exchanged and a new individual cactus can be born through a fruit.
Does Every Cactus Bloom?
When I had my first cacti (about 20 years ago) I always thought that only specific special cacti can blossom. Imagine my surprise when one of my oldest cacti decided to form flowers almost four years after I got it. So I asked around (back then the internet wasn´t really a thing) why my cactus all of a sudden decided to bloom now. Eventually, I literally bumped into a succulent expert who was finally able to answer my questions.
Every Cactus has the ability to bloom but building flowers requires quite a lot of energy. This is why younger cacti rarely bloom. Ideal growing conditions are also a factor. If the cactus doesn´t have everything it needs then it won´t be flowering any time soon.
So while every kind of cactus can flower it can sometimes take years until they do, as was the case with my cactus.
When Do Cacti Flower
Cacti flower when they are old enough and when they have enough energy to build blossoms to reproduce. Depending n the cactus variant it can take anywhere between a year and 100 years until a cactus is old enough to flower. Providing the optimal growing conditions can exhilarate the time until a cactus blossoms.
There are a few cacti that are known to flower frequently and fast like the Parodia or the Notocactus.
So if you want a flowering cactus then consider getting one of these.
If you have a cactus that should be flowering frequently but doesn´t then check if all of the growing conditions are ideal.
You can read more about that in the next section.
How To Encourage Your Cactus to Bloom
If you are frustrated because your cactus still doesn´t flower even though it is old enough and maybe it even is a cactus that is known to flower often then don´t worry, there are steps that you can take to encourage your cactus to bloom.
Check the Soil PH
Even though cacti are known to be able to grow in most soils with a wide range of PH they still have their own preferred soil PH.
The perfect PH value can be different from cacti variant to cacti variant so you should look up the ideal range for your specific variant.
Try to correct the Ph value as needed with fertilizer or organic material until it is in the proper range for your cactus variant.
Give the Cactus Enough Sunlight
Unsurprisingly, a cactus needs a lot of natural sunlight in order to thrive.
So make sure, that your cactus gets enough sunlight during the day.
The cactus should get at least 4 to 5 hours of direct sunlight each day.
Water Your Cactus Regularly
It is well known that cacti don’t require a lot of water but you should still water them twice a month.
I usually have a repeating reminder in my calendar that reminds me that I have to water my cactus every two weeks.
Depending on the variety you should either water them directly or simply spray them with a little bit of water.
Cacti Sometimes Need a Cooler Period In Order to Bloom
This is something that I only found out recently. And by recently I mean about three years ago.
But some cacti need a cooler period of time in order to bloom.
I usually do this in the winter where I put all of my cacti inside (they would probably die outside in the winter anyways) and I will put them in a location that is a little cooler than what they are used to.
This cooler new location will encourage them to blossom. In nature this is naturally happen ind once a year.
Yes even in desserts there is a temperature difference between summer and winter. And Cacti need it in order to thrive.
So try to simulate it as well as possible.
Just don´t let the temperature near cacti drop below 20 degrees F or your cacti will most likely die.
If you follow all of these steps then your cactus will, if everything went well, start to flower within a year.
Just keep in mind that you should keep all of these steps in mind during the whole year. So periodically check the soil PH and water your cacti regularly.