This is a seven year old diffusa that I started from seed.
It's a beauty! I just started some myself this past winter. Needless to say, they've got a way to go!
Nice plant, but are you sure it's 7 years old? It looks much younger then that.
The plant in this folder "P1010004" is 7 yeears old also and it is 4 times larger. Mine range in size a lot. I need to get all of my plants into deeper pots. The shallow pot may be slowing down it's growth. The largest one that I have just sprouted it's first pup also. Wish I had more of these, they are my favorite to grow.
Here is a link that might be useful: all 7 year old
Here is a link that might be useful: http://www.flickr.com/photos/8912065@N06/sets/72157600441847544/
carlk. I wouldn't worry about how slow it grows, really.
If you force it during the summer, with fertilizer extra water, it will simply split it's sides & be prone to rot , anyways.
I doubt it'd bloom any sooner. It is just one of the slower growing cacti. I've had flowers on Aztekium & Geohintonia, sooner.
Although I think only Pelecyphora asseliformis seens to be about as comparably slow to reach flowering age.
But I must admit, Aztekium hintonii, isn't in much of a hurry either.Patience is definitely required...
Hope your cacti do well, this spring (get 'em extra heated up & then watered early!)