How to root Trichocereus (San Pedro) cuts?

Introduction

Rooting cactus cuts is one of the two main ways to propagate cacti (plants in general), the other being growing from seed. The major difference between the two is that a cutting would be a genetic clone of the parent (the plant the cut was taken from), whereas, growing from seed can result in variations of traits.

The method of cutting and replanting a cactus cutting would be referred to as cloning.

One of the main advantages of rooting a cut is speed to full growth and to guarantee a genetic clone of the parent. A cutting is generally of an adult plant and the only thing it needs to focus on would be establishing a full root system, generally 1 to 2 seasons. Growing from seed takes around 3 years to get to adult growth and a few more seasons to get to the same rate of growth as a fully established plant.

Etiolation

Ah, that word again. Etiolation is where the cactus grows skinny compared to the normal body of the plant. This is normally due to two main factors, lack of heat and/or light. When rooting cuts, etiolation can happen while the plant is establishing roots, while still trying to grow. There is not enough energy to grow roots and the body of the plant.

Etiolation can largely be avoided by feeding high Potassium (seaweed feed), no Nitrogen feeds and lots of light. I generally do this for 2 seasons, but this can be brought down to 1 full season to give the cutting enough time to establish a good root system.

The bigger the cutting, the less chance of etiolation. Always bank on some etiolation as it is just a part of the growing process, the object is to try and minimise it as much as possible.

Etiolated Tr pachanoi (San Pedro)

You can see the skinny top growth.

How Long to Roots?

Rooting can take anywhere from a few weeks to a few months depending on the specific cacti and the Cactus Gods. Patience is required here, but, the reward is well worth it.

In this post, we will discuss the different rooting methods and when each is best suited.

Preparation

The main thing to remember when rooting cactus cuts is to ensure that the cut section of the plant is fully calloused over, this generally takes around a week depending on the season and moisture in the air. The cut part of the plant will get hard to the touch and a light brown colour, this is generally a good marker that the cut has calloused over enough to root.

It is generally a good idea to apply sulphur or charcoal to the fresh cut. Sulphur is a natural fungicide to help keep fungal infections from happening, charcoal is used to dry out the wound quickly.

Calloused Cutting

This is a fully calloused cut with sulphur applied

Should you use rooting hormone?

In the UK, you can only get natural rooting powers / gels. Avoid using any form of gels as they will add moisture and increase risk of rot Gels are actually anti fungal so shouldn’t cause any issues (we learn something new every day). I apply this rooting powder when potting up. Does it make a difference? In all honestly, I am not sure but won’t hurt.

This is the organic rooting powder I use.

Side Note: I have seen some growers apply rooting powder to the open cut straight after chopping, then apply sulphur and then dry out. I think this would probably be the best use of rooting powders.

Substrate Options

Whatever substrate you use must be free draining and fast drying to minimise risk of rot. As a rule, normal substrate mixes can be used if they are catered for cacti (high grit component).

Some growers do the initial rooting in straight perlite and as soon as roots show, they swap out to a normal substrate mix. While this will work, it is not something I generally do myself (except for the water tek I will describe below).

The substrate I offer is well suited for rooting cuts as it only has a 40% organic compound, you can find substrate mixes here too.

Rooting Method 1 – Conventional

1. Add substrate to a pot that is wide enough for the full base of the cutting to sit in.
2. Plant the cutting:
   1. Spring / Summer – You can bury the base of the plant about an inch down to stabilise it and maximised surface area for rooting.
   2. Autumn / Winter – During non-active growing months, you are much safer sitting the cut on top on the substrate to maximise airflow. You can use wooden stakes or string to prop the cut up and stop it from falling over. Rooting over winter is hit and miss; and depends on the environment as to its likelihood of rooting or not.
3. Avoid watering your newly planted cutting for a couple weeks.
   1. Spring / Summer – you can lightly water every now and then to trigger root growth, must be sparingly. Bottom feeding is a good option here.
   2. Autumn / Winter – Personally, I would avoid any watering of any kind as it only increases risk of bad things happening.
4. Keep your new cutting in a bright location but out of direct light until roots start showing. You can slowly move it into more direct light over a few weeks to acclimate him again. Try get your guy into direct light as soon as safely possible to aid in establishment and avoid etiolation.
5. If rooting in straight perlite / pumice / molar, I would recommend repotting as soon as roots start showing.
6. Once roots are showing, you can grow him as per normal with slightly less watering / feeding volume.

Rooting Method 1 – Unconventional (Water Tek)

Rooting in water? Are you mad? Two seasons ago, I would have laughed at this suggestion.

Rooting in water has produced the fastest roots I have come across. On average, rooting takes 7 to 9 days, which is unheard of.

Considerations

This will only work during active growth; you are begging for trouble doing this method over Winter unless you have a pretty beefy indoor setup.

I have found this method to work/not work for the following genetics:

• Trichocereus pachanoi (San Pedro) – Zero issues, I generally get roots within a week.
• Trichocereus peruviana (Peruvian Torch) – As above but slightly long, around 9 to 12 days.
• Trichocereus bridgesii (Bolivian Torch) – Normal bridges has no issues. I did have some challenges with TBM (Trichocereus bridgesii Monstrose) where the cutting got waterlogged and just never pushed roots. The plant was fine after taking him out and letting him dry out.
• Trichocereus scopulicola – I wouldn’t recommend rooting scop cuts in water, they just get waterlogged (same as TBMs).
• Trichocereus hybrids / crosses – Water tek should work but I have yet to fully test all crosses. I have successfully rooted scop crosses.

Water Supply

Ok, this is where everything comes together. Water is not the issue when rooting cuts, bacterial build up is. When water is left to stand, it becomes a breeding ground, and this is where problems arise.

As long as you are switching out the water daily / every other day, you should avoid 99% of issues. Personally, I use sparkling spring water. Sparkling spring water is slightly acidic which, in my head, is a good thing 😊. Regardless, to be safe, please use spring water.

Rooting in Water

Roots after 7 Days

Process

I have only tried two methods of rooting in water:

Straight Spring Water

This was how I started my journey and works well:

1. I spray the container (I use an applicable sized drinking glass) calloused ends with 70% iso propyl alcohol, not a lot, just enough to cover the area and allow it to dry quickly. I am not sure if this helps but I like to think it kills off any nastys that may be present.
2. Sit the fully calloused cutting in the glass. The cut base should be wider than the bottom of the glass to allow for space for roots to grow.
3. Fill the glass / container with enough fresh spring water to fully cover the base of the cut.
4. Switch the water out daily / every other day to keep the water clean and bacteria free.
5. Do a happy dance when you get roots in a week.
6. As soon as you see roots, I recommend replanting the cutting into suitable substrate. The new roots will be weak due to no resistance (substrate) so it is best to repot as soon as possible.

Spring Water & Perlite

1. Same as above, I spray with 70% iso-propyl alcohol.
2. Bury your cut about ½ inch to 1 inch in a suitable container with no holes.
3. Fill the container with spring water to the top level of the perlite with the base of the cut fully submerged.
4. Switching out water here is a little tricky but must be done. Every other day will be fine.
5. Don’t forget the happy dance when you see roots popping.
6. With this method, you can keep the plant rooting in the water for longer as there will be enough resistance in the perlite to strengthen the new roots.

Water Tek Final Word

As with everything, there are no guarantees in life. I am only giving you my personal experience and results will vary. As far as risks go, the biggest risk would be rot at the base due to bacterial infections, this can be greatly minimised by swapping out for fresh water often. I have yet to get any rot using this method (it will happen I am sure). Even if you did get rot, a bit of surgery to remove the rot and re-callous over, you are good to go again.

It would be best to try this out on a test cut first to get confidence in the process.

Conclusion

Rooting cactus cuts is very easy, it just takes time. For complete beginners, I would recommend the standard rooting process of sticking the cut in substrate and waiting. Once you’ve gone through the process, you can get a little braver and try different methods (Eg: Water Tek).

Always remember, cacti are the gift that keep on giving. If you have any issues during the rooting process, you can always recut and start again.