I have a bridgesii cutting that is stalling and I suspect its because the bottom part which is buried an inch deep is completely hardened off and brown like tree's bark. So I want to ask whether I should cut that off so some of the blue/green flesh and a freshly calloused not woody wound can root better. Would this work or should I continue being patient?

That's how it should look under the soil-- in fact I'd bury it a little deeper than an inch if I were you-- it will anchor better.

And don't really water the soil or it could rot-- especially bridges-- you could mist its skin every few nights to help it a bit, but cactus generally want to grow, and it will do it when it's ready.
Just make sure it's getting some modest sunlight in the daytime so it's aware it can root in sun-- it'll do its thing when it "feels" adequate conditions to activate.

Yeah, the cacti root at their own pace. One of mine - a particularly scabby and hopeless-looking peruvianoid - took a couple of years. I found adding grit seemed to help. Patience is a virtue, after all.

My three bridgesii cuttings rooted within 3 weeks of lying flat and drying / callusing. The cut ends were dipped in sulphur powder, I wonder if that helped strike the roots?

The brdigesii in question is getting less sunlight than my pachanoi/peruvianus which are all growing so that must be the case. I was not sure if the thick skin on my bridgesii was having trouble respirating and in turn not realising it was underground. When the weather warms my 3 unrooted cacti will be moved into more direct sunlight. Thank you for your responses.

That callused, woody cutting end is exactly what you want. The greatest risk to a planted cutting is that it will rot before it strikes roots. That woody callus is it's best protection against rot. The cutting doesnt need to be watered until it starts to put out new green growth. That is the sign that roots have started. Thats when you can start watering it. Rooting hormone isn't needed for cactus cuttings. The cutting will know exactly what to do, and it will be fine. It just takes time.

My pachanoi is putting out new green growth, but roots haven't started yet.
Should I still withhold watering?

I put some water in the tray yesterday, to let the medium soak it up. The idea being that I want the medium to hold some humidity, but not to be wet. The water disappeared from the tray, even though the medium is perlite and pebbles.

My preferred method is to allow a cutting to callus, and then to plant it directly in the soil in its permanent location. I have never taken the additional step of first rooting the cutting in air or in a temporary medium like perlite and gravel.

The main reason to withhold water during the rooting process is that without roots to absorb moisture from the soil, the cutting will just sit in damp soil and risk developing rot. It has no way to absorb or benefit from the moisture in the soil until roots are there. Before striking roots, the moisture does not help the cutting, it just puts it at risk for rot.

After a few weeks or months, when roots start to form, you can see the change in the cutting. A cutting that was doing nothing for a month or two will all of the sudden start to errupt with new growth. Thats the sign that the roots have started, its drinking water again, and growth phase is on! And since the cutting is already planted in its long term location, there is no worry about damaging the baby roots by digging the cutting up and re-planting it.

Jagube I'm not sure about your cutting in perlite and gravel. I've never rooted in that medium before and so I'm not sure what to expect with it. All the best.

But I know that what I have described above works and is safe for cuttings. I have planted many cacti this way, with very few setbacks, and minimal etiolation. This is how these two cuttings will be planted once they callus. Its very important to minimize the risk of rot. Rot is the greatest killer of cuttings.

That's right, cuttings will simply produce roots when they're ready. From what I've observed, they are mostly guided by a contrast in illumination. Occasionally, I've had specimens pop out roots if one side of the plant is constantly shaded, even when they've already been growing happily in their pots for however long.

My particularly reluctant, encrusted, skinny peruvianoid seemed to respond to spray misting before finally popping roots so I get the feeling some response to moisture occurs even before the cutting produces roots.