There are few cacti that I find as rewarding as Astrophytum All of them are beautiful and are well worth growing. I am fascinated by their very geometric shapes and by their wonderful flowers. My plants started flowering three weeks ago. I can never remember their starting quite so early. Unlike Mammillaria which have a glorious show of flowers for a few weeks and then no more flowers for a year, Astrophytum produce a succession of flowers from April to early Autumn.

I grow my Astrophytum in a 50/50 mixture of John Innes No. 3 and grit to which I add a shake of ground oyster shell and a shake of slow release fertiliser.  I have found that they are sensitive to over watering so I tend to start watering them when my other plants are having their second watering and I finish watering a couple of weeks earlier in the Autumn than the rest of my plants.  I grow them in a sunny part of the conservatory where the temperature does not drop much below ten degrees in the winter, but I have grown them in the greenhouse which is only kept just above freezing and they seemed to be quite happy there.

All Astrophytum are slow growing. Even ornatum which is the biggy of the family takes quite a long time to get there.  The smallest in the family is asterias.  It is spineless and resembles a sea urchin. Its yellow or red and yellow flowers can completely hide the plant body. This is the slowest growing and the most delicate Astrophytum, consequently it is very highly rated on the show bench.  The secret seems to be to remember that it is small and slow growing and to water it accordingly.

Astrophytum myriostigma (known as the Bishops Mitre Cactus because that is its shape) has no spines but is covered with white mealy flecks. Its yellow flowers are smaller than the others in the family but can be produced five or six at a time.

The largest flowers, (yellow with a deep red centre and four or more inches across) are produced on Astrophytum capricorne.    Capricorne has long curling spines that can be white, golden, ginger or black. 

I have never known Astrophytum to produce offsets but they are easily grown from their large black seeds.