Today's project was to core some barrel cacti in order to force branching. This is my first time doing this, so I thought I would document the process step by step. Coring is a reasonably common maneuver among growers and it's how they achieve massively multiheaded golden barrels and the like. You remove the growth center and the plant sprouts new heads to survive. For example:



and here is a plant that lost its center late in life, but has survived and sprouted new heads.



Even if nobody here ends up doing the same thing, you can still get a good idea of what's actually at the center of a barrel cactus. The core is significantly below the highest level of the stem, guarded by spines and obscured by a whole lot of wool.

My primary tool for this project was a drill with a 3/8" bit, and to follow up I used a pair of tweezers to remove spines, wool, and flesh. In one case I used a paring knife to deepen the cut. Eye protection is essential for the drilling part, as sharp spines fly away at high speed.

This first plant is Echinocactus grusonii, the golden barrel. I used a paring knife for the final step, to really remove a lot of the core.









Another plant of the same species. For this plant and the rest, I was more conservative in what I removed, going by my usual guideline for coring, which is that it's better to remove too little than remove too much. Because you can always go back later if the center comes back and the second round is always really easy. And I like to test the limits, so I know where they are.







This is F. viridescens, a BC native






Another one of the same species






This is what ended up on the floor



And here are the plants at the end, headed for a place with shade protection to heal.



Mission accomplished!

This happens to mine by accident occasionally but I'm afraid I could never do it on purpose. Makes me queasy just looking at those plants.

If you go on Youtube looking for this stuff, you'll find videos where people just stick a knife into the core and do it that way ... I thought the drill method would be better because it allows me finer control over what I damage and what I remove. Less actual damage to the plant, less queasiness overall that way.

This is something I've thought about for some time, and I kept extra plants for this express purpose, so if they all die, it's not a big deal. The first step was accepting a high probability of failure.

Will it help to seal the hole with something?

Also, can you do this with a golf ball size cacti?

I'm not planning on sealing the hole, but I suppose one could try that.

You don't want the damaged area to be too big compared to the size of the overall plant, but I would imagine one could make something work with plants smaller than the ones in the pictures (which are in 6" pots).

Is rain collecting in the core a concern?

Yes, it is a potential concern. That's why I decided to do the operation at the start of our dry season. Hopefully by the time the rain resumes again in the fall, the plants will be properly healed.

Baja_Costero said:Yes, it is a potential concern. That's why I decided to do the operation at the start of our dry season. Hopefully by the time the rain resumes again in the fall, the plants will be properly healed.

Even when healed is it a concern? I imagine if it is hot enough, it would evaporate fast enough?

If you sealed the "core" hole, I imagine you would have instant rot. You want that hole to dry out, not rot. That's why Baja is waiting for the dry season.

I did weigh the option of making the cut so that water could never pool, ie. providing a little sideways canal so the water would flow out that way. But it seemed like more damage than was really necessary. We do have the luxury (or burden, depending on your perspective) of having essentially zero rainfall until October at the earliest. And I expect I will be making the rounds after the first few storms, blowing the water out of there, to be on the safe side. But I imagine in the long term it will be okay, especially when there's new growth squeezing the hole shut afterwards.

The bottoms of the holes I drilled are turning orange. Note the ribs just barely visible in there as 13 radial lines.

This is interesting, I love it when a specimen is being manipulated and cultivated to be unusual, like bonsai, espalier, arborsculpture, pleaching, braiding, grafting... How did this practice come to your attention?

Not sure, exactly. It's associated with multiheaded barrels in my mind, but I don't know when I made that connection. I have been intentionally damaging growth centers for a few years now, just not using power tools until recently.

Here we are 18 days in, and it looks like my guesswork was pretty good.

2 of these plants look like they are coming back at the center, 2 of them look like they're done.

One of the golden barrels (which was drilled much shallower than the other)



And one of the native barrels


For comparison here's the other native barrel from before, further along, and pretty much done I think.


I will be taking out the drill again and going another 5mm or so deeper to finish off the 2 that are coming back.

Baja_Costero said:Here we are 18 days in, and it looks like my guesswork was pretty good.

2 of these plants look like they are coming back at the center, 2 of them look like they're done.

One of the golden barrels (which was drilled much shallower than the other)



And one of the native barrels


For comparison here's the other native barrel from before, further along, and pretty much done I think.


I will be taking out the drill again and going another 5mm or so deeper to finish off the 2 that are coming back.

You should get a brace bit with an auger . Much better depth control

I re-drilled those 2 plants a little deeper (right) and drilled a new one from scratch (left), leaving me with this collection ... so far, so good.

I found a better bit than the one I was using before, to get a flatter profile in the center.

Baja_Costero said:I re-drilled those 2 plants a little deeper (right) and drilled a new one from scratch (left), leaving me with this collection ... so far, so good.

I found a better bit than the one I was using before, to get a flatter profile in the center.

Baja, would this work on echinopsis, parodia, gymnocalycium and rebutia?
Also, what kind of bits do you use?

I would think it could work on just about any cactus, probably some a lot better than others, but you gotta try to find out.

I used a pretty generic bit for wood (sharp protruding tip at the end) to do the cleanup and one with a flatter tip to do the bottom. I don't think there's anything particularly special about the bits, I keep them all jumbled together in a box and grab whatever looks good in the moment.

Baja_Costero said:I would think it could work on just about any cactus, probably some a lot better than others, but you gotta try to find out.

I used a pretty generic bit for wood (sharp protruding tip at the end) to do the cleanup and one with a flatter tip to do the bottom. I don't think there's anything particularly special about the bits, I keep them all jumbled together in a box and grab whatever looks good in the moment.

Hm. Good Idea on the brad point- they are much better at centering. Metal bits are much hard to pinpoint, Also brad points have a better cutting edge at removing fibrous material.

I cored mine the day you started this post. Must have done something wrong as nothing is going on as of today.

Bold move! Nothing much is going on here, by way of branching, either. I think it's too early.