Why are Some Cacti So Darn Hairy?

I don’t know about you…

But out of all my cacti, the hairy guys (and gals) are definitely some of my favorites!

They’re unusual, fascinating plants so I just had to dedicate an article to them.

Let’s find out what purpose this wooly, sometimes fuzzy hair serves and if it’s actually real.

I’ll also give you some of my top care tips for this type of cactus to ensure your plant stays happy and healthy!

Without further ado;

So, Why Do Some Cacti Have Hair?

It turns out it’s not a fashion statement as I’d first hoped!

The hair actually protects the cactus from extreme weather conditions in their natural environments.

Take one of the most famous hairy cacti ‘the old man of the Andes’ for example (pictured below).

My 'Old Man of the Andes' (Oreocereus trolli)
My ‘Old Man of the Andes’ (Oreocereus trolli)

As the name suggests, he hails from the mountain ranges of Argentina and Bolivia in South America.

Temperatures here can reach up to 95 degrees Fahrenheit during the day and just like us humans, cacti can also get sunburned.

While we will wear a hat, sunblock, and shades to protect us, cacti use their hair to cover up from this intense daytime sunlight.

On the flip side, the temperature can drop dramatically overnight sometimes reaching below zero.

When it does, the hair then acts as a blanket to keep the cactus warm.

It does this by trapping air between its spines and stems creating a layer of insulation to survive those cold, desert nights.

That’s not all, hair isn’t only to control temperature...

Hair can be used to capture what little moisture may be in the air during times of drought to help stay hydrated.

Finally, you may notice that even some hairless (read: bald) cacti may grow hair around new buds. This is to protect them from the intense direct sun until they are ready to fend for themselves.

That’s Great, But Is This Wooly Stuff Real Hair?

Yes, it’s real hair.

But it’s not the same as human and animal hair as ours contains a protein called keratin which is the difference.

Cactus hair is made of modified spines but be careful…..

Underneath that cute, fuzzy, wooly hair are sharp yellow thorns.

A close up image of my Oreocereus trolli with the sharp yellow spines poking through the wooly hair
Watch out for those thorns!

I should know, I pricked myself four times the other day while repotting this individual…ouch!

Care tips for your hairy cactus

Hairy varieties have similar needs to other cacti.

Having said that, you should identify your particular variety to learn its individual needs as most differ slightly.

In general, they are used to heat and thrive on lots of direct sunlight, approximately 6-8 hours each day.

Ideally, they should be planted in a terracotta or unglazed ceramic pot with drainage holes and good quality, well-draining soil.

Personally, I use 1 part cactus and succulent potting mix with 2 parts horticultural grit.

During the winter months, hairy cacti will go into dormancy and will need a snug, cool, low-light environment.

Important: Do not water during this period.

When spring comes around, you can gradually reintroduce the hairy fella to sunlight and water.

Finally…Watch Out For Pests!

Maybe I’ve been unlucky, but in my experience pests such as mealybugs, spiders, and mites are drawn to hairy cacti as it gives them a warm hiding place.

My advice is to check regularly and keep an eye out for any signs of damage or disease.

Which Types Do You Have?

If you have a hairy cactus, I’d love to know which type and why you love them in the comment section below!

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