So I have come to the realization that the cactus that is showing all the scarring and that has multiple offshoots is completely rootbound in the 3gallon pot that it is in. Could this be contributing to the scarring? If so, should I try to transfer it to a larger pot? I dont even know how I would go about doing so, with how spiky it is its going to be hard to handle. I will probably have to break apart the plastic pot its in to get it out.

My other thought was to cut off the three largest arms, and replant these. I would leave the single 4rib arm that sprouted from the cut section and let that continue to grow on the main stalk, and leave it in that 3 gallon pot. Hopefully more arms will sprout and grow quickly with how well the main stalk is established.

What do you guys think would be the best course of action?

Yeah, it'll love you for giving it a bit more root space and some fresh compost. Wrap it in numerous layers of newspaper and thin plastic packaging foam to avoid getting spiked. 3 gallon pot sounds like a big job, you might get away with laying the whole thing on its side to get the pot off intact.

Taking cuttings as well would be a great idea if you have the space for more pots.

So, I say both is the best course of action but I'd wait 'til the roots have settled into the new pot before taking the cuttings as too much stress on the plant all at once could cause problems.


EDIT: It makes sense that they'll try to grow new roots when the current ones run out of space/trace nutrients. Do you fertilize?

I have not fertalized this year. I have some veg and bloom nutes for cannabis, I could mix a small amount of the bloom nutes into the next watering, as the veg is very high in nitrogen which I'm told is not good for cacti

I always just diluted normal organic tomato feed to 50% of that suggested on label to counteract excess nitrogen, at least for trichs. They can cope with a little more nitrogen than most other cacti. Maybe you could add a dash - 10%? - of the veg feed to the flower food.

My trichs loved the tomato food at half strength every couple of weeks throughout the summer but I don't have any more of that since moving house

It would have helped to be able to read the label for N content, at least. Trout will have the 'acceptable to trichs' figures somewhere but I can't search for that right now.

I'll stick to the bloom nutes at a diluted strength for now, going to give it a feeding tomorrow and see if that makes a difference with anything.

Trichs are closer to tomato than other cactus, that's why their grow rate is so fast compared to the cactus world.

If the soil is exhausted, cactus would like to be feed to keep growing. Of course exces of nitrogen are dangerous and cactus raised with a lot of fertilizers could be more sensitive to sickness. That's why, as dfz said, half dose of fert every 2 weeks (during the growing season) is my choice. Most of the time it's high a nitrogen fert and sometime (~1/3) it's a cactus fert.

Where do you find cactus fertalizers? I have never seen anything marketed as a cactus fertalizers. What is the N.P.K. values of the cactus fertalizer? I have a hydroponics store not too far from me where I go for all my fertalizers and growing equipment, so as long as I know the proper N.P.K. values I can find something to match it or get very close.

Nitrogen - Phosphorus - Potassium

I know what it stands for, I'm wondering what the ratio is for the fertalizer made for cacti.

I'm currently using a 2-4-4.

I have a bottle of cactus fertilizer, it's 4-7-7 with trace elements 0.02% boron, 0.004% copper, 0.04% iron, 0.02% manganese, 0.002% molybdenum and 0.004% zinc. I purchased it in the garden section of a large DIY store (in Germany).

I also use a guano-based fertilizer which is NPK 7-3-6, with B/Cu/Fe/Mn/Mo/Zn at 0.01/0.002/0.05/0.02/0.001/0.002.

Thus you can see that the cactus fertilizer has higher levels of trace elements and I'd say that's part of what the root-bound specimen is missing.

But still, for my trichs that organic tomato fertilizer was the dog's danglers and you really don't have to worry so much about the nitrogen with most of this genus.

So winter temps have moved on in to the area over the past few weeks and I have brought my cacti inside for the year. However, my biggest one has an arm that is continuing to throw out roots, even though I have watered it and it should be going into dormancy for the winter.

What I want to know is, would it be ok to cut this arm off just below the roots that it's producing, and get it planted? My main concern is doing it, and then it getting far enough along in the season that it stops it's growth and stops producing roots, and then possibly rot.

Or would it be best to let it be for now and wait til spring to cut and transplant? By that point I fear there would be a large amount of Arial roots and I dont know how exactly that would effect the whole cacti.

Those roots aren't a problem, you can cut or wait as you please. Probably it's better to wait until spring before potting on the cutting but that's plenty of time for the surface to callus over. Just make sure it's somewhere dry (R.H. <60%)

Sometimes they will throw out rots like that if they can feel that they are near a wall or something like that. In the wild they like to grow down the sides (and up?) of cliffs so they are just trying to do that.

You could cut or not. It is nicer to cut in the growing season in my experience.