You do know that the 'Moon Cactus' that are grafted must be grafted to a green growing cactus. These plants produce no food for themselves due to no green. So they must get it from the plant grafted to. If they produce seed, I hope it is reverted to the past all green types otherwise as soon as the seed germinates, it will die. I had some all yellow plants germinate and as soon as they used up what was in the seed pod, they died. They propagate this cactus by the little off shoots they produce. And graft onto another stock.
Rare that some bloom. Great for you.
Stush
