Astrophytum is a genus of cactus from Mexico into Texas. They are well suited to growing in pots and containers and will produce yellow flowers from an early age.
Six species in the genus with a number of sub species and named cultivars available for sale,
It is the amazing shape of the main plant body that makes this such an attractive plant. A few common names including Bishop’s Hat Cactus and Star Cactus give us a hint as the the shape of this plant.
It is Astrophytum myriostigma var. quadricostatum with is four cornered look and grey body that is called the Bishop’s Hat Cactus . This is a spineless variety with pale lemon – yellow flowers. This is one of the easier species to grow.
Astrophytum ornatum is one of the larger growing species, the ribs which vary in number from 5 – 10, spikes appear down the ribs and the body of the plant is green with small white flakes. Again yellow flowers appear form the top of the plant.
Astrophytum capricorne commonly called Goat’s Horn Cactus and and Astrophytum nudum are other popular types.
Propagation is usually from seed which appear in the small fruits after the flowers.
- Seeds can be germinated in specialist seed raising mix. Or a mixture of coco peat, peat moss, river sand and pumice.
- Seeds are sown on the surface.
- Cover the container with a clear cover which will increase humidity and this speeds up germination.
- Place the seeds in a warm position with some morning sun.
- Mist spray to keep the seeds moist.
- Seeds are fast to germinate, usually within 5 – 8 days
- Keep the seeds moist by mist spraying until they reach around 1 inch (2.5 cm) in height.
- At around 5 months the seedling should look rounded and plump.
- At this stage that can be potted up into a general cactus potting mix with 50% other drainage material added.
- Use a specialist cactus and succulent pot, usually unglazed and with a large drainage hole.
- These are a plant that like sun, in warmer climates you grow them under 70% shade cloth.
- Repot in spring and alway use a small sized pot so the plant has a confined root run. You should only need to repot every 2 – 3 years at most.
- Only water when the soils dry and less frequently in winter.
- Fertilise with just a pinch of slow release fertiliser and dolomite lime when repotting.