How to Root a Cactus Cutting
This guide was written with the San Pedro Cactus in mind, but you can follow these instructions for most columnar cacti that grow from cuttings. Please note there are some large varieties of cactus like the Saguaro Cactus that will not root from cuttings.
What you will need:
Some gloves;
Perlite*;
Peat, or premium peat-based potting mix;
An appropriate-sized plant pot with good drainage holes. For small cuttings, we recommend a pot at least 25cm H x 20cm W. For large cuttings, you will need a pot at least 40cm H x 30cm W, possibly larger;
Optional: rooting hormone powder.
*Perlite is a silicate material produced by subjecting volcanic glass to extreme temperatures. The end result is tiny, irregular-shaped white pebbles that resemble Styrofoam. They are incredibly light on account of the fact that they are full of air pockets. These air pockets mean it has excellent aeration qualities, whilst also being able to hold small amounts of water, which is perfect for plant roots. Due to these qualities, it’s often used in all areas of horticulture as a soil additive, particularly in cactus cultivation. Perlite also has the added benefit of being a sterile medium, which makes it perfect for rooting our cactus. You can buy small bags of perlite from Bunnings, but this can be quite expensive compared to buying a large bag at a hydroponics store or speciality gardening store.
Optional Step - Use Rooting Hormone
Rooting hormone has been shown to promote root formation and speed up the rooting of cactus cuttings, but it’s not a strict requirement.
Consider using rooting hormone:
If you’re trying to root cacti in winter when rooting naturally takes longer;
If the particular cutting is very important to you and you want to try everything you can to maximise success;
You’re impatient, like us.
Rootex-P is our preferred rooting hormone for use with cacti and you can find it in our online shop. The active constituent in Rootex-P is 3g/kg Indole Butryic Acid (IBA). Studies have concluded that IBA produces a larger number of roots in a shorter period of time than Indole Acetic Acid (IAA) and Naphthalene Acetic Acid (NAA).
To use with cacti: simply dip the freshly cut end of your cactus into the powder and then leave the cutting to dry in a bright and well-ventilated area out of direct sun or rain. Then follow the normal rooting procedure. Do not wet/mist the soil as the packet instructs or your cactus cutting may rot. Powder is preferable to gel rooting hormones in cactus propagation for this same reason.
Rooting Instructions
Create a cactus rooting mix by combining the following components and mixing well:
3 parts (75%) perlite;
1 part (25%) peat or premium peat-based potting mix;
Add the rooting mix to your pot until it is about 2/3 full;
Add another thin layer of perlite;
With gloves on, take your cactus cutting and place the calloused/cut end into the centre of the pot, so it is resting on the perlite in the centre of the pot;
Hold the cactus in place with 1 hand, and with your other (or a helper) fill in all around the cactus with your cactus rooting mix. You do not have to completely fill the pot if you don’t want to, just as much is needed to ensure the cactus won’t fall over when you release it;
That’s it! You’re done. Easy, right?
Where to put your cactus to root?
Put your potted cactus cutting in a dry, well-ventilated location with plenty of light but try to keep your cactus out of intense and prolonged direct sunlight at this stage. Your cactus is currently focussing its energy on growing roots, if you put it in the sun now it could get sunburnt which will stunt its growth and possibly even kill it.
Good locations to put your cactus to root are:
A windowsill that doesn’t get heaps of direct sun;
An undercover outdoor area like a deck or patio;
Well-ventilated shade or greenhouses;
A very well-lit room.
Bad locations to put your cactus to root are:
North-facing windows that receive heaps of direct sun;
Dark rooms;
The middle of your yard in full sun;
In your pool;
A swampy cave.
Now all you have to do is leave it alone.
How long does it take for a cactus to root?
Rooting typically happens faster in the warmer months, but generally, it will take about 3-4 weeks. After about 2 weeks gently lift your cactus up and check the base to see if it has any roots, if not, put it back, if it’s just started put it back for a few more days.
Cactus roots are very sensitive, so try and minimise the number of times you pull them up to check. Once you have a few small roots forming it can have its first watering.
Can you root cuttings straight in the ground?
Yes, you can root cactus cuttings straight in the ground or in garden beds outside. Just keep in mind that too much sun can sunburn them at this stage so choose an appropriate location or use a shade cloth over them until they are established. The other consideration when planting cuttings straight into the ground is a surplus of moisture. To minimise the chance of your cactus rotting we recommend planting the cactus cutting directly into gravel, not soil. The best way to do this is to dig your hole and fill the bottom with gravel, place the cactus cutting in the hole and then completely fill around it and compact it down. If it is a large cutting you may also want to use a stake to hold it upright until roots grow and stabilise it.
