Mammillaria thornberi ssp thornberi

I've a nice clump of Mammillaria thornberi ssp thornberi which is currently in flower and seems to be very happy.


However, I've noticed that some of the smaller (newer?) stems have died back/dried out. I seem to remember reading somewhere that this rather annoying habit is quite characteristic of this species in cultivation. Does anyone have any tips on how I might stop the die back or, for that matter, any general advice on looking after this beauty?

Mammillaria thornberi ssp thornberi

Hi Simon,
I was asked this question at the Oxford Show recently, in which I had entered a plant of M. thornberi - no prizes though....
I have grown this for a number of years and occasionally a stem does dry up, but generally speaking I don't have much trouble with it. It does have this reputation, though, so I guess I have been lucky, with this plant, though another did almost die, and I managed to rescue an offset and grow it back to a reasonable plant.
I use a very open compost, water fairly normally - as for most of the Ancistracanthae - and dry off from October to March. I have been told that early water can help, as in habitat in SW Arizona, they get long dry summers, but often some early rains. I haven't tried that myself, as in Feb/March my greenhouse is too cold for me to venture with the watering can.