Star Cactus Plant
The Astrophytum Asteria plant is loved by cactus-growing fanatics for its distinctively stubby little star-like appearance. They are such an easy plant to grow and make a great addition to any cactus houseplant display or terrarium.
This spineless cactus makes for an interesting talking point with its greenish-gray star-shaped body that is uniformly sectioned into eight and covered with tiny white hairs. Pretty white dots descend from the top of the cactus to accentuate the ridges of each section.
Position Full sun
Watering Water thoroughly but infrequently, water less in winter
Size Height up to 2 inches. Diameter up to 6 inches
Climate Semi hardy zones 8 to 9 (19° F / -7° C)
Seasonality Evergreen, Winter Dormant
Toxicity None Toxic
Flowers Yellow Daisy-like flowers from March until May
Unsurprisingly Astrophytum Asteria or Star Cactus plant has acquired a number of other names including Sea-urchin cactus and Sand Dollar cactus due to its sea creature-like appearance. It is sometimes referred to as Star Peyote which is a reference to its similarity to the Peyote cactus.
Flowering occurs between March and May with each plant boasting a singular yellow flower with an orange center. Towards the end of spring, the blooms will develop into berries during late spring, covered in fine woolly hairs, of pink, red, or gray.
Astrophytum Asteria – Star Cactus Care
In its native habitat of Texas and Mexico, the Astrophytum Asteria grow successfully outdoors and thrives in full sun or partial shade. If you intend to grow in cooler climates, this plant will need to be grown indoors and positioned in full sun.
During the winter months, move your Astrophytum Asteria to a slightly cooler position but still in a bright spot with plenty of natural sunlight. Moving it to a cooler position will help to encourage flowering in the following year.
Even a well-cared-for plant of this species is relatively slow-growing so patience and perseverance will serve you well here. You can expect a height of between 1 to 2 inches and a diameter of between 3 to 6 inches once fully mature.
Astrophytum Asteria requires far less water than you might imagine, even by cactus standards. During the summer months, water every 2-4 weeks and always allow the soil around your cactus to dry completely between watering.
In the winter, watering should be kept to an absolute minimum. This is due to Astrophytum Asteria having a summer growing season and essentially laying dormant during the winter months. Whilst your plant will still grow during dormancy, it does so at a much slower rate and so has less requirement for water and nutrients.
As with summer watering, only water when the soil around your cactus is completely dry.
To test the dryness of the soil press your finger at least a quarter of an inch into the soil or prod the soil around the drainage holes in the bottom of the pot. If the soil feels completely dry, you can go ahead and water your cactus.
Keep an eye out for any signs of overwatering. These include soggy, mushy, or brown color around the base of the cactus. This is usually just below the surface of the soil line. You may notice that your cactus reduces or even stops growing.
If your Astrophytum Asteria looks wrinkly or feels soft to the touch, then it’s likely that it needs water.
Don’t ever be tempted to use a spray bottle or mister as a watering device for cactus. This is because their native habitat is dry and arid and they are not used to the high levels of humidity that a water mister can invoke. Also, allowing them to remain damp for extended periods will cause them to wilt or rot.
Like most other cacti, always use well-draining soil for planting Astrophytum Asteria. The roots need to be free from excess moisture to allow them to get the oxygen they need to thrive.
Use a peat-free soil or coconut coir mixed with minerals such as grit, sand, or perlite. Planting in the right type of soil will encourage healthy growth and help to prevent root rot and disease.
Ready-mixed cactus and succulent soil is the easiest option and there are many to choose from with availability to either purchase online or at any good garden-supply retailer.
Alternatively, you can easily make your own good quality well-draining cactus soil at home. Start with one-third organic matter such as a good quality peat-free compost or coconut coir. Mix this with two-thirds of minerals such as grit, sand, or perlite.
Since Astrophytum Asteria is relatively easy to grow, the only special requirement it needs is a well-rested winter period to give it the best possible chance of flowering successfully the following year.
To provide a well-rested winter period, you should reduce the frequency and amount of water and also reposition your cactus into a cooler position just for the winter months. Doing this will increase the chances of your cactus flowering in the following year.
The Astrophytum Asteria cactus flowers from March until May. Flowers are yellow with an orange center and measure approximately 3-inches in diameter. After following, the blooms turn into hairy-looking berries that are either pink, red, or gray.
To encourage a good, strong root system and healthy growth use a ready-mixed cactus fertilizer and dilute with water. Only fertilize during the summer month every 4-6 weeks. There’s no need to fertilize your Astrophytum Asteria in winter. We suggest a diluted 10-10-10 fertilizer.
Astrophytum Asteria is a slow-growing cactus that will only need to be re-potted every 2-3 years. When re-potting, always use free well-draining soil and hold off watering for a few days to allow your cactus to acclimatize. Thereafter, water as described above.
How To Propagate Astrophytum Asteria
Astrophytum Asteria can only be propagated from seed. Use good quality shop-bought seeds or, if you’re lucky enough to own a mature plant, harvest the seeds from the fruit that appears after flowering. For the best chance of success, use seeds that are as fresh as possible.
After flowering, collect seeds from the capsules found within the ripe fruits. Open the capsule to remove the seeds and before sowing, allow them to dry thoroughly.
Use cactus soil but add extra sand to ensure even more effective drainage. Scatter the dried seeds over the soil and lightly cover them with more sand. Avoid placing the seeds in direct sunlight. Young plants and seedlings need a warm, well ventilated, and sheltered position with plenty of light and partial shade if very hot.
Water just enough to keep the soil moist and until the seeds germinate, which can take up to 8 weeks.
Once germinated, reduce the amount of water. They will take a year or so to develop into the familiar dome shape and 2 years plus for the ridges and spikes to form.
Common problems with Astrophytum Asteria (Star Cactus)
Overwatering, allowing the soil to remain wet or not using a well-draining soil are all common causes that can lead to root rot in a Astrophytum Asteria cactus.
Identifying root rot is not always simple but there are a number of tell-tale signs to look out for. These include the top of the cactus becoming saggy or turning yellow, an unpleasant smell, or the main bottom of the stem turning brown at the base just below the soil level.
To treat your Astrophytum Asteria for root rot you should first remove it from its pot. Then, very carefully brush off any soil that remains around the roots.
Roots that are brown or black and soft and mushy are rotten and need trimming off. Always use sharp, sterile scissors or a knife to remove root rot and allow the cut to dry before repotting with fresh soil in a clean pot.
Water thoroughly, but less frequently thereafter.
Often found in between the ridges of Astrophytum Asteria, Mealybugs produce a distinctive cotton-like mass on the plant’s surface. They feed on the plant’s sap by piecing their straw-like mouth into the foliage.
Use household insect spray, neem oil, detergent or soapy water to wash them away. Repeat regularly until the infestation subsides.
Scale are static shell-like parasites that sit in the ridges of Astrophytum Asteria and feed on the sap from within. Infestations lead to the plant looking sick and wilted. You can treat scale by using a diluted detergent or soapy water to wash them off.