Echinocereus rigidissimus, I think. Grown under lights?

Wow, that is a nice specimen. Thanks for sharing. I do believe it is a E. rigidissimus.

Dawn

It may also go by the name Echinocereus rigidissimus v. rubispinus. It has very beautiful flowers!

~Rosemarie

Here is a link that might be useful: Echinocereus rigidissimus

Thanks to you too, i get a name and so can find the cultivation practice (it's only 3'6'' high)
It grows on my balcony May to October, and under fluo lights in winter. I bought it last May