Grafted gymnocalycium, flowers that don't open

[keithp2012]

I have heard some grafted colored cacti don't have flowers that open, my purple gymno had neon pink flowers that stayed closed for 3 weeks until they rotted and fell off.

I forced open one flower past the sticky residue keeping petals shut, and it was developed but pollen never split open it had sticky residue on it and leaving it in a cup overnight did not help.

Are these better used as seed parents as the female part is functionable but will it be receptive to other gymno pollen?

Think my cactus is gymnocalycium mihanovichii 'black cap' though I see on Google 2 flower colors available.

[snarfie]

I don't know, i haven't got the chance yet to figure it out

[adetheproducer]

Given it more direct light and heat if you can, my gymno's only fully opened flowers with the hottest sunniest days in summer.

[keithp2012]

The cacti flowered again, this time now during summer in the sun and heat. All my other cacti blooms opened this still fails to open? I wonder if this cultivar has bloom issues?

[george76904]

some of the grafted ones tend to abort their buds, but I know that some manage to flower successfully, they seem to prefer the heat rather than direct sun in terms of flowering.
-Will