The Star Cactus, botanical name Astrophytum asterias, is a beautiful cactus native to Texas and its bordering parts in Mexico. Natively it grows in the shade of larger bushes, making identifying a wild specimen somewhat difficult.
It is a barrel-shaped cactus of diminutive size, perfect for desktops. Instead of spikes protruding from the nodes along the ribs, it has tufts of soft and white fur-like hairs. It is also sometimes called the Sea Urchin Cactus owing to the resemblance of its rounded form to sea urchins.
The Star Cactus is prized for its unique shape dotted with attractive white spots and showy flowers. While it can be grown outdoors in U.S. Department of Agriculture plant hardiness zones 9 through 11, this cactus also makes an attractive houseplant, thriving in a sunny window or under grow lights. With proper care, your cactus will bloom indoors from late spring to early summer.
Star Cactus Main Characteristics
| Common Name | Star Cactus, Sand Dollar Cactus, Sea Urchin Cactus, Star Peyote |
| Botanical Name | Astrophytum asterias |
| Synonyms | Echinocactus asterias |
| Family | Cactaceae |
| Genus | Astrophytum |
| Type | Cactus |
| Native Range | Texas, Mexico |
| Common Cultivars | Akabana, Alpus, Elephant Sun, Feather Flower, Goryuu Kabuto, Superkabuto, Godzilla |
| USDA Hardiness Zones | 9 to 11 |
| Mature Size | Height: up to 2 inches; Spread: up to 6 inches |
| Bloom Time | Summer |
| Propagation methods | by seeds |
| Sun | Full sun, Bright shade |
| Soil | Sandy, Well-drained |
| Toxicity | Non-Toxic |
Star Cactus Care
Astrophytum asterias is a unique plant that makes a great addition to any indoor space. However, it takes exacting care and patience for this plant to reach maturity. This guide will cover all the basics of its care, from watering and lighting requirements to tips for propagating your plant. With a little bit of TLC, your cactus will thrive for years to come!
Light and Location
Although the Star Cactus is a desert plant, it grows under bushes or shady rocks in its natural habitat. If you are growing your cactus indoors, bright shade would be ideal. It’s vital to ensure that your plant is getting enough light, as this will encourage blooming. However, too much light causes the greens of the cactus to appear washed out. Although it will grow just fine in full sun, giving it some shade results in more vibrant colors.
Watering
Obviously, this plant is a cactus, and as such, it is quite drought-tolerant and can survive long periods without water. From spring to autumn (March to October), water the pot sparingly. Ensure that the soil drains out entirely before a session; you don’t want any residual water to stay in the pot. In winter, suspend watering altogether; it can survive just fine without any.
Temperature and Humidity
The Star Cactus is used to the hot and dry desert climate. In summer, temperatures can range from 70°F (21°C) to 100°F (38°C). In winter, it can drop down to 50°F (10°C), but it will only survive the cold if the plant is kept dry.
Humidity
The humidity level should be low, around 30-40%. The cactus will be susceptible to root rot if the air is too humid. Replicate desert conditions if possible.
Fertilizer
These cacti are slow growers. You can use potassium-rich fertilizer in spring and summer to speed up the process. In winter, suspend fertilizing entirely.
Did you know?
Both Echinopsis and Astrophytum asterias share the common name Sea Urchin Cactus.
Cultivars of Astrophytum asterias
There are many cultivars of the Astrophytum asterias, some of which are listed below.
- Superkabuto – Wildly popular. White fuzz covers most of the plant. Many hybrids are available in nurseries.
- Alpus – Fanned out body instead of globular. Star-shaped.
- Akabana – Large red flowers, unlike any other cultivar.
- Elephant Sun – It has wrinkly skin like an elephant. Quite unique.
- Godzilla – Similar to Elephant Sun, but the skin is even more wrinkled, resembling snakeskin.
- Feather Flower – extremely showy flowers
- Goryuu Kabuto – Only five large ribs.
And many more.
Propagating Astrophytum asterias
To propagate your cactus, you will need to use seeds. You can harvest seeds from the fruit of the cactus, which will separate itself from the cactus when ripe. To harvest, cut the fruit in half and remove the seeds. You can also purchase seeds online or from a nursery.
To sow, place the seeds on top of the soil and lightly cover them with sand. Keep the soil moist and in a moderately cool place until germination occurs. Germination usually takes around 2-4 weeks. When the seedlings are big enough, you can transplant them into their own pot. Be very careful not to damage the roots when transplanting.
Potting and Repotting Star Cactus
Astrophytum asterias don’t need to be repotted very often. Once every two years should suffice. When you do repot, make sure to use a pot that is only slightly larger than the previous one. This plant hates when its roots are disturbed, so be gentle. Avoid a pot that is too big as it is only an invitation for diseases and pests.
When potting, use soil that drains well. A cactus mix would be perfect, but you can also make your own by mixing potting soil, perlite, and pumice. Avoid using fertilizer immediately after potting; wait for the plant to become established in its new home.
Common Pests and Diseases
Mealybugs and spider mites can be a problem. Sometimes scale insects as well, but they’re rarer. If you notice any pests, take immediate action to get rid of them. Watering down the affected area can sometimes get the job done, but you might need something more heavy-handed if the infestation is severe.
How to Take Care of a Star Cactus (Astrophytum Asterias) (Video)
FAQ
How To Propagate Star Cactus?
This cactus and its hybrids propagate by seeds. Sow them in a moist potting medium kept somewhat cold and wait for germination. Seeds sprout easily but need frequent repotting to be kept alive until maturity.
What Eats Star Cactus?
Mealybugs, spider mites, and occasionally scale insects are the occasional visitors. All can be treated with water or insecticidal soap. Consult a professional if the problem becomes severe.
How To Grow Astrophytum asterias?
Astrophytum asterias is a very easy cactus to grow. It can be grown indoors or outdoors in USDA hardiness zones 9-11. In cooler climates, you should bring it inside during the winter. The cactus likes soil that drains well and requires little watering. Fertilize with a potassium-rich fertilizer in spring and summer and propagate by seeds.
How Slow Do Astrophytum asterias Grow?
These cacti grow slowly and can take many years to reach maturity. Therefore, patience is a virtue when growing this cactus.