The Star Cactus

Astrophytum Haku Jo
Astrophytum Haku Jo

Astrophytum is a small genus of only six species. They grow in very harsh environments, very hot, poor soils and subject to weather conditions.

Like many succulent varieties will grow in full sun outdoors in the right climate however that are usually grown in containers indoors or protected indoors over winter.

So look for warm to hot conditions, free draining soil and good amounts of light. Low humidity is also important.

Commonly called the Star Cactus because as you look down on them they are appear star shaped. And yes they are grafted onto other cactus.

The six species are :

  • Astrophytum asterias
  • Astrophytum capricorne
  • Astrophytum caput-medusae
  • Astrophytum coahuilense
  • Astrophytum myriostigma
  • Astrophytum ornatum
Astrophytum sp.

All are from Mexico with A. asterias also being found in Texas.

However these are a very easy plant to hybridise, so you will will find all sort of Astrophtyums, lots of hybrids from Korea, Japan, Thailand and also in California.

How to Grow Astrophtyum

Grow Astrophtyums near a sunny window, summer temperatures of around 70°– 75°F (20° – 24°C) will work well. They can take warmer temperatures if acclimatised slowly and they will tolerate slightly lower temperatures during winter as long as they are kept dry. Try to avoid heavy frosts and no freezes.

  1. Full sun to every bright light.
  2. Very well drained soil/potting mix.
  3. Low to medium humidity in cultivation.
  4. Never over water.
  5. Never Cold and wet.
  6. Hold back on water during succulent dormancy in winter.
  7. Fertilizer – Very little and low nitrogen.

Soil For Astrophytum

Astrophytum myriostigma Fukuryu
Astrophytum myriostigma Fukuryu

The correct soil mix for Astrophtytum will not only keep your plant health bit also help it to bloom.

Astrophtytum are prone to fungal attack, so a very free draining mix is needed.

The simplest mix would be a standard cactus and succulent mix with pumice and perlite added. You are looking for a slightly alkaline soil that drains freely

  • 4 parts Standard cactus and succulent mix
  • 1 part pumice
  • 1 part perlite.

A more complicated mix could include

  • 6 parts pumice
  • 3 parts perlite
  • 2 parts akadama
  • 3 parts vermiculite
  • 1 part peat moss/coco coir
  • 1 part kyodama
  • 2 parts seed raising mix

Whenever you repot Astrophytums do so into a dry or nearly dry soils. This helps avoid any damaged roots developing rot. Wait 10 – 14 days before watering