Oncidium back bulb propagation

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I wrote about receiving an intergeneric Oncidium with an incomplete name tag in this thread:
Oncidium makai

When I repotted it, two back bulbs looked as though they were attached only by dead rhizomes. I cut through the rhizomes, and where I made the cuts, the rhizome was indeed dead. The rhizomes at the bases of the pseudobulbs also looked like they might be dead, but I know this is not always the case.

I potted the two separated pseudobulbs, plus the one pseudobulb with a matured but dwarfed new growth, into large-particle perlite. This has fairly sharp, irregular edges, so it tends to stay put in a pot. It holds water but has large air spaces around it. I buy it at a local hyrdoponics shop. I am also trying it in S/H, so far with good results. It is very much lighter than LECA.

The two back bulbs went into a single 4" / 10cm round plastic pot. One of them was completely blackened and shriveled at the base. I knew from past experience this did not mean the inside was dead, and the bulb still had a chance of making new growth. I set them in the sunroom and sprayed with water every day. A week ago I gave a good dousing with KelpMax, Inocucor and fertilizer.

Three days ago I noticed a little green shoot at the base of the bulb that was green all the way to the base. Here is how it looks today, triple the size:



Three days ago there was nothing visible on the other back bulb in the same pot, the one black all around its base. Yesterday I saw two tiny green bumps at the very top of that pseudobulb, one above each old leaf scar. Here they are today:



This happens sometimes with old Oncidium back bulbs. With care these growths can form new plants. Some people take old back bulbs and lay them on top of barely-moist sphagnum moss, hoping such growths will root and grow.

I gently pulled the perlite from around the base of that pseudobulb and saw the beginnings of a new growth from the rhizome:



I am going to wrap some sphagnum around the growths at the top of this pseudobulb when they begin forming roots. When well-rooted I will cut them off and pot up separately. I will let the growth from the base develop normally. I will continue spraying these pseudobulbs frequently to encourage those growths to develop.