House and garden day

so blipped a plant.
These three cacti are a few years old.The flowering one has produce two flowers this year.

The one in the centre has only ever produced 1 which dried.
I know you're not supposed to repot them but I have to that one today.

It's been fabulous weather today.Back out into the garden ;)
Any Cacti experts out there who can tell me why it's only had the one?