15 Cactus Myths – Learn to Enjoy Your Spiny Friend

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Robert Pavlis

Cactus are very weird plants. They almost never have leaves. They sit there and do nothing for a good part of the year. They don’t flower – or do they? If you are old enough to remember all of the cowboy movies on TV, you are sure to know that you can always stop by a cactus and get a drink.

My first foray into horticulture was a collection of over 100 different cactus, under lights in my bedroom. At that time I went to Europe, in part to see “native cacti”. I’ve grafted them, and even grown them from seed. Fast forward 40 years, and I still have a cactus growing in the garden (zone 5).

For this post I have collected together all of the cactus myths that I could find. Enjoy.

Golden barrel cactus source: Pamla J. Eisenberg
15 Cactus Myths, Golden barrel cactus source: Pamla J. Eisenberg

Are Cacti and Succulents the Same Thing?

Succulents are a large group of plants adapted to storing water in their leaves, stems and roots. Cactus are a subset of these and “have small, round, cushion-like structures called areoles from which spines, branches, hair, leaves and even flowers grow.” If a succulent does not have areoles, it is not cactus, even if it has spines.

real cactus flower
real cactus flower

Succulents are native to most parts of the world, but cactus are only native to North and South America, with one exception. I learned that when I got to Spain and found out that in order to see “native” cactus, I had to return home. Cactus do grow in many countries, but outside of the Americas, they are non-native plants.

Compost Science for Gardeners by Robert Pavlis

Rhipsalis baccifera, the mistletoe cactus, originates from Central and South America, but is also found in Africa. It is believed that birds carried it there a long time ago. The African population is now considered to be a subspecies.

There are about 1700 species of cactus, which have a life span of 10 to 200 years. They are specialist plants that can absorb a lot of water quickly. A fully grown saguaro (Carnegiea gigantea) is said to be able to absorb as much as 200 gallons (760 l) of water during a rainstorm.

Cactus are Desert Plants

That is a common myth. A lot of cactus do grow in desert conditions, but some also grow in rocky mountainous regions and some like the Christmas cactus grow on trees in tropical rainforests.

This means that not all cactus need to be hot and dry. Quite a few can take cold weather, like Opuntia humifusa, an Ontario native that grows quite well in my zone 5 garden with no winter protection, or the Christmas cactus that like a more normal watering schedule.

Can You Drink the Water From a Cactus?

When you are lost in the desert and real thirsty, can you cut open a cactus and drink from it?

A cactus does hold a lot of water, but it is not a drinking vessel just waiting to be opened. The water is stored in spongy cells full of acids and alkaloids that taste terrible and can cause vomiting, diarrhea, or temporary paralysis. “The notable exceptions to this rule are the prickly pear and one species of barrel cactus, the fishhook barrel (Ferocactus wislizeni). While both of these plants are fairly unpleasant to eat raw, they have less-concentrated levels of the detrimental chemicals and could give you a bit of hydration in a pinch. Cactus fruits are a better bet, though many are also unpalatable if eaten raw.”

Many cactus-like plants, notably the Euphorbia, are also toxic and their sap can burn your skin and mucus membranes.

Cactus spins have probably developed in part to ward off predators, so there are some animals that can consume cactus.

Better take a water bottle on your hikes in the desert.

Real cactus flower
Real cactus flower

Cactus Don’t Need to be Watered

A common myth says that you never have to water them as house plants. How can any plant live without water?

There is also the story of the lady in New York who phoned her sister in Arizona every few weeks to find out if it was raining. If it was raining, it was time to water her cactus.

The barrel cactus can live a long time without water, but it should be watered, especially in summer when it’s growing. Many cactus do go dormant in our homes in winter, so a drink once a month is all they need.

Christmas, Thanksgiving and Easter cactus all prefer regular watering but occasional drying won’t harm them.

Cactus Need to be Hot

Cactus are slow growing from seed
Cactus are slow growing from seed

Many cactus grow in the desert which leads people to believe that they need to be hot all of the time. However, deserts can be quite cold at night, especially in winter when they get snow. Cactus also grow at high elevations where it never gets really warm.

Not all cactus can take frost, but many can tolerate it, if they are dry.

Cactus are Slow Growers

It is true that most cactus are slow growers but some species grow up to 6″ (15 cm) a year. If they receive they right growing conditions they will show annual growth. The problem with most cactus in the home is that they don’t get enough light to grow.

Cactus Don’t Flower

Cactus flower on new growth. If your cactus is not growing, it won’t flower.

Some cactus need special conditions to flower, such as diurnal (day/night) temperature changes, or a different watering routine. They also have to be old enough. A barrel cactus may not flower until it is 30 years old.

Another big factor is light. Most homes do not provide enough light for the traditional cactus to flower. Spending the summer outside, in full sun, can make a big difference. The new high intensity LED grow lights provide enough light to make many flower.

Cactus are Pest and Disease Free

The skin on cactus is very tough – it’s designed not to allow water to escape. For this reason they have few insect pests. They are also not affected by many fungal issues unless that protective skin is compromised, or they are overwatered.

They can get scale and mealy bugs which can be resolved as described in this video.

YouTube video

Feng Shui Boos the Cacti

“According to Feng Shui belief it is said that cacti, although beautiful, does transmit bad energy. It is said that this bad energy is carried in their ”prickly and sharp” thorns.” Placing them in the bedroom can disturb your sleep and peace.

This is partially true. If you get a thorn in your finger, it can hurt all night long!

What is “bad energy”? I don’t remember that from physics class?

Can Cactus Reduce Radiation From your Computer or Cell Phone?

I have dealt with this in another post called: Can Cactus Reduce Radiation From your Computer or Cell Phone?

Cactus Hatch Baby Tarantulas

Someone bought a cacti at a local plant nursery. Later, it exploded and scattered baby tarantulas everywhere – or so it’s claimed.
“That is a full-fledged Urban Legend and one of the best-known ones, which has passed from person to person by word-of-mouth for so long, it has been around the world several times. Oddly enough, persons repeating this story commonly (and falsely) state that it happened to someone they know personally.”

Tarantulas don’t deposit their eggs in cactus, the egg sack does not explode and baby tarantulas are harmless.

I also kept tarantulas for a few years, but my wife made me get rid of them – now I only have plants – and a wife!

Are Moon Cactus Real?

Moon cactus are real, but grafted onto root stock
Moon cactus are real, but grafted onto root stock

What is a moon cactus you ask? I have known about these for ever, but I didn’t know they were called moon cactus. They are the colorful cactus that sit on top of a green cactus stem, as in the picture.

Moon cactus are real. They are a mutation that contains no chlorophyll so they can’t make their own food. To keep them alive, the Gymnocalycium mihanovichii (ie moon cactus) is grafted onto a rootstock cactus, such as Hylocereus. The lower part is green, photosynthesizes and feeds the upper part.

Grow them just like other cactus, but if the top comes off, it will die unless it is again grafted onto another cactus – a process that is actually quite easy to do.

Fake Flowers on Cactus

Cactus have one of the most beautiful flowers in the plant world, but they are not easy to flower. No problem – just glue some fake flowers on them and people will buy them. And that is exactly what happens.

Cactus straw flowers - not real cactus flowers
Cactus straw flowers – not real cactus flowers, source: Succulent Plant Care

Cactus sell better if the supplier glues some fake flowers on them.

Some are labeled as “Cactus Straw Flowers” – that is a give-a-way, but at least the producer is honest. If every cactus in the tray has a flower, they are not real, remember cactus are difficult to flower. If it looks as if the flower is glued on – it is. If it feels like a dry straw flower – that is exactly what it is – real cactus flowers are quite soft.

To be clear, the flowers are not fake. They are real flowers, just not cactus flowers.

In most cases you can pull off the fake flower since it has been hot glued on. If you wait a while for the cactus to grow, it should fall off on its own. Removing the flower may result in a scar, so it really is best not to buy these things.

Is Tequila Made From Cacti?

No it’s not. Tequila is a distillate made from blue agave that grow in Mexico.

However, there is a new Texas Vodka, called Spike, made from prickly pears, which is a cactus.

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Robert Pavlis

I have been gardening my whole life and have a science background. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

9 thoughts on “15 Cactus Myths – Learn to Enjoy Your Spiny Friend”

  1. https://cwf-fcf.org/en/resources/encyclopedias/flora/cacti-of-canada.html

    Cacti native to Canada are:

    CORYPHANTHA VIVIPARA VAR. VIVIPARA – BEEHIVE CACTUS, PINCUSHION CACTUS

    OPUNTIA HUMIFUSA – EASTERN PRICKLY PEAR CACTUS

    OPUNTIA FRAGILIS – BRITTLE/LITTLE PRICKLY PEAR CACTUS

    OPUNTIA POLYACANTHA – MANY SPINED/PLAINS PRICKLY PEAR CACTUS

    I have Opuntia fragilis growing wild in my garden – love it despite being attacked frequently by dislodged pads. The beautiful flowers (blooming now) are so beautiful

    Reply
  2. Thanks for the article; I had suggested you write about this topic. I would add the myth that “a shriveled cactus is dying and needs water.” Most cactus grown outdoors begin to shrink as days get shorter and the weather gets colder in preparation for winter but will plump up again in spring. The Opuntia humifusa you have is a prime example. But this may be so obvious that it’s not a myth.
    Also, bajtra is a liquor made in Malta from cactus pears.

    Reply
  3. Hi, Can you do an article on soil for Bonsai trees? Too much controversy on the subject, mostly a push on Akadama which is imported from Japan very expensive, and many myths.

    Reply
  4. Hi Robert

    Nice article on one of my favorite groups of plants. Maybe just a correction: although it is true that most cacti are native to the Americas, there a few that originate from elsewhere. For example, some species of the genus Rhipsalis come from Africa. Rhipsalis baccifera (mistletoe cactus) is an epiphyte of forests and as such makes beautiful indoor plants.

    Regards

    Johan

    Reply

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