Great news!

If you keep it dry until it's well healed, the cactus will probably survive.

As for the photo - the important part is clear enough, that's all that matters.

I think Tom nailed it, see: http://www.llifle.com/Encyclopedia/CACT ... duliformis

Unrooted cactus cuttings can bloom, so flowering would not prove the graft took.

Nice job and I agree with the above advice repot 👌 Fitting many plants in a single pot takes more time but saves space. It doesn't have to take that long, you can do the whole pot as a unit -just unpot them an pull them apart without completely separating them, set them in the new pot and add more ...

Apparently "decorational" is a recent California slang coinage, a combination of "decorative" and "ornamental". Knowing how these things work, we're probably stuck with it.






seems

I grew up on a farm, I wouldn't worry about stepping in the cow manure - except there might be more cacti under the cow manure.

From the link I sent you about Trichoderma: "Colonies’ colors range from dark and light green to yellow and white. The green color, in some species, is sometimes only expressed after light exposure." You said "I accidentally knocked one plant out and had to repot it. The whole wick wa...

A few points to cover here: Trichoderma colonizes a variety of plant roots, and grows worldwide. Good chance will protect the roots of these plants from fungal attack. It also eats cellulose - if that's cotton cord, it will consume it. It's good for the plant roots, but you should avoid breathing th...

"They grow cacti and succulents in the streets and yards... "

It might be something like the way most older houses around here have sword ferns in their landscapes - some of them are planted, but a lot are volunteers.

"If you ignore the cow manure you can spot more than 10 E. vivipara... "

This is not a place you want to go barefoot.

Great pictures.

I think heat may also have some influence, which could explain why they do so well in the greenhouse - it traps heat.

Agreed - when they get that crowded, it's time to pot them up.

Hard to be sure at that age, but probably Echinopsis peruviana (syn Trichocereus peruvianus). It's something in the Trichocereus group, at least - many of those in cultivation are random hybrids. They're not very fussy about soil - it should be slightly acidic to neutral, and well-drained.

They are slow-growing - do you have a photo from when you first got it to compare? Euphorbias aren't very fussy about soil. It should be well-drained, preferably neutral to slightly acidic - but they will tolerate slightly alkaline soil as well. As for its future, it should continue to grow slowly f...