Astrophytum Asterias (Star Cactus): Types, How To Grow And Plant Care

One of the most interesting and well-loved species of cacti across the globe belongs to the Astrophytum genus, known as Astrophytum asterias, or the star cactus.

These low-growing plants come from Texas and Mexico, but they are grown across the world for their unique looks, resembling a star. 

Why Should You Grow A Star Cactus?

The star cactus is easily recognizable thanks to its dome-like appearance with prominent ribs. You might also know this cactus as the sand dollar cactus, sea urchin cactus, or star peyote.

It’s incredibly easy to grow, whether you want to grow it outdoors during the summer (if you live somewhere warm all year, you can leave it outside all the time), or indoors as a houseplant.

Each rib features white areolas, covered in small silvery hairs. They don’t get any taller than 7cm, and reach about 15 wide at maturity, making them perfect for areas with limited space, whether that’s on a windowsill inside or on top of a table, or as part of a rockery outside.

Their small stature is precisely what has made them thrive in arid environments, helping them to avoid being eaten by animals, by hiding under rocks and camouflaging with the floor, and fallen leaves. It also stops the plant from losing too much moisture, too.

These fantastic plants also produce bright yellow and orange flowers at the very top of the plant, and if pollinated, these are followed by oval-shaped pink fruits. It can take years for the cacti to produce flowers (see also Flowering Cactus Varieties And Care), however, especially if they aren’t given the right conditions.

A Note On The Vulnerability Of Star Cacti

It’s worth noting that the star cactus is classified as endangered, thanks to the destruction of its natural habitat, by creating more roads and clearing land for farming, the over-collection of this plant, and plant poachers. 

This plant is not to be confused with Lophophora williamsii, also known as Peyote or the dumpling cactus, which has a similar appearance. Some people do make this mistake and harvest this plant when they mean to take the dumpling cactus instead.

Always ensure that you source plants for your collection from reputable sellers, so you know that your plant hasn’t been taken illegally from its natural habitat.

How To Grow Star Cacti

The star cactus isn’t particularly fussy when it comes to growing conditions, but there are two things it needs: direct sunlight and soil that has decent drainage.

The soil can be as poor as you like, as these plants are used to soil with very little nutrients, but it does have to drain well.

Star cactus plants will not be damaged if you forget to water them. Only water when the soil has completely dried out, and avoid watering these plants at all in winter.

You don’t need to feed the star cactus, and it is very easy to provide the plant with too many nutrients, in which case it will elongate and become distorted, and it could even burn the roots.

If you really want to feed a star cactus, do so when you repot it (see also How To Repot A Cactus) and water it, using a specially formulated cactus feed, at half the recommended strength.

Can You Propagate Astrophytum Asterias?

You can propagate a star cactus, but only through sowing seeds. You can either buy the seeds from a reputable retailer or collect them yourself through a plant you’ve already got, waiting until the flower has dried before harvesting the seeds.

You do have to be gentle with the seeds, as they are quite fragile, and sow them in a lightly damp cactus soil mix. 

Cover them lightly with compost, and make sure you seal the container with a plastic bag or wrap, poking a few ventilation holes in the top. 

Keeping the humidity in like this helps to increase the chances of germination, as well as putting the container in a bright, warm location, away from direct sunlight.

Star Cactus Varieties You Should Grow At Least Once

There are many cultivars to choose from, as these plants are easily hybridized. Here are just some different star cacti you should try growing at least once.

Astrophytum asterias var. nudum

This particular star cactus is popular with beginners, not just because it is easy to care for, but because it’s also one of the most common. 

The Latin word nudum means naked, referring to how the plant doesn’t have white speckles covering its ribs. 

It’s one of the more classic-looking varieties, as you can easily see the shape of the ribs of the plant.

Astrophytum asterias cv. ‘Super Kabuto’

If you’re after something that looks a little fancier, ‘Super Kabuto’ is covered in white hairs that form spots, usually in a mosaic-like pattern, giving the plant a dramatic look.

Astrophytum asterias ‘Miracle’

Similar to ‘Super Kabuto’, this particular cultivar has similar white spots, but they are much more prolific, nearly covering the whole of the plant, and the plant gets bigger.

It’s worth noting that ‘Miracle’ is particularly difficult to grow from seed, and when it was imported to Japan in the 1880s, it was sold for a vast sum of money! 

Many ‘Miracle’ star cacti plants are a hybrid of ‘Super Kabuto’ because they are so difficult to germinate.

Astrophytum asterias cv. kikko

The name Kikko refers to a special samurai armor that features hexagonal plates, so you might see the resemblance in this particular star cactus, which forms hexagonal sections on the ribs.

Final Thoughts

Astrophytum asterias are fantastic plants that are worthy of any plant collection. They are very easy to care for, and they can live for many years. 

You will have to be patient, however, if you want to see flowers on this particular plant, as it can take years for it to mature enough to produce flowers.

That’s not necessarily a bad thing when you think that these plants are unique without the flowers, and the blooms are just the icing on the cake.

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