When does a Euphorbia inermis flower? What's necessary?

[nachtkrabb]

For now next to 18years this wonderful Euphorbia inermis grows at my place. In spring 2018 it got this deep pot as I had read that it would grow a tap root, & next to pure mineral soil. I would love to give it a bigger pot, but how as its "tentacles" are growing in bows?

Usually the plant had spent its summer on a balcony, its winter in the living room. But November last I had read that it would need a cool & dry winter to flower. The flower would be abundant and even fragrant! Cool, a fragrant Euphorbia! Immediately I moved it to a cool place (about 14°C / 57°F) for the winter.
It didn't protest so I think we will repeat that.
But this summer, after one (1) cool & dry winter, it didn't flower. Well all right.

Do you grow a Euphorbia inermis which flowers in a container: Would you kindly please share how you treat it?
How old or big does it have to be for blooming?

Besides: My plant grows tentacles at the end of some of its tentacles. My neighbor has a similar plant & would like hers to do so, too. Is that just a "personal preference" or is there some special condition? Does it do that in case of some need...?

All tips & tricks are appreciated.
Thank you,
Nachtkrabb
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