Cryptanthus acaulis, also known as Earth star or Starfish plant, is a small bromeliad grown for its wavy-edged, spiny leaves. Although it can bloom as a houseplant, the flowers are small and hidden. Most growers prize the plant much more for its unique, attractive foliage.
The entire plant only reaches about 5 inches (12.5 cm) high and 6 inches (15 cm) wide, making it a good choice for humid rooms where space is limited – like bathrooms and kitchens. Older plants may flatten a bit before they bloom and then slowly decline.
With proper care, this plant can live for up to 5 years indoors – or indefinitely when propagated from offsets. In this post, I’ll cover all aspects of Cryptanthus acaulis care, including how to keep it happy and healthy in your home for decades.
Cryptanthus Acaulis Care
Cryptanthus acaulis isn’t hard to grow, but it does have high humidity and moisture requirements. I place this beautiful bromeliad in the moderate difficulty category. If you can meet Earth star’s need for moisture, you’ll be rewarded with lovely foliage for many years.
Here’s a brief rundown of Cryptanthus acaulis care guidelines:
- WATER: Keep the plant’s “tank” filled with water
- HUMIDITY: High
- FEEDING: Once monthly spring – summer with half-strength fertilizer
- LIGHT: Half-day of sun from an east- or west-window
- TEMPERATURE: 65 – 85 degrees F (18 – 29 degrees C)
- SAFETY: Non-toxic to dogs, cats, and humans
- DIFFICULTY: Moderate
Keep reading for more in-depth growing instructions, including potting, propagation of offsets, maintenance, and troubleshooting.
Earth stars are terrestrial bromeliads, which means they grow on the ground like ordinary plants unlike epiphytic bromeliads that grow on the sides of trees. All bromeliads absorb moisture from the air through specialized scales.
Most types also have leaves that form a “vase” in the center of the plant to hold water (see Silver Vase Plant). The leaves absorb anything that falls into the vase, which you can think of as a water tank or reservoir. This makes fertilizing bromeliads easy by just spraying the foliage.
Cryptanthus acaulis has a water tank, but it’s very shallow because the plant’s leaves spread flat and wide. Water your Earth star by pouring distilled water or rainwater into the shallow tank. Maintain a constant supply of water in the tank, and never let it dry out completely.
Apply water to the potting soil as needed to keep the roots lightly moist in spring and summer. In fall and winter, water less often – but never let the roots dry out completely.
Be careful of overwatering. Do not water so much that the potting medium becomes soggy and wet. For the best results, water a little bit frequently (instead of a lot infrequently). Too much water can lead to root rot, which will quickly kill your plant.
The most important part of Cryptanthus acaulis care – and the one that many people struggle with – is keeping humidity levels HIGH. This plant needs lots of moisture in the air to really thrive. Follow these guidelines to make your Earth star happy:
- Mist your plant daily using a water bottle filled with room temperature (or lukewarm) water. If you live in a very dry area or have central heating in winter, you can even mist twice a day.
- Place the plant on a humidity tray – a shallow watertight tray filled with pebbles and water. Make sure the water stays below the pebbles! See my post on How to Make a Humidity Tray for Houseplants for more information.
- Place a humidifier in the room near your Earth star if possible. I use the Honeywell Cool Mist to keep my humidity-loving plants happy. If you can’t get a humidifier, see my post on How to Increase Humidity for Houseplants Without a Humidifier for more ideas.
You can also grow Cryptanthus acaulis in a terrarium to keep humidity levels high. The University of Missouri Division of Plant Sciences has a great article on growing plants in terrariums if you’re interested in giving it a try.
Feed your Cryptanthus acaulis with a balanced houseplant fertilizer diluted to half strength. Spray it directly onto the leaves once a month in spring and summer. Reduce feeding to every other month during fall and winter, again spraying diluted fertilizer onto the leaves.
You can use diluted liquid fertilizer if you like. But I prefer to use my favorite Jack’s All-Purpose Houseplant Fertilizer for my Earth star. I mix it using a 1/4 teaspoon fertilizer to a gallon of distilled water. Read my review of Jack’s Fertilizer to see why I love it so much!
Another important aspect of Cryptanthus acaulis care is providing enough sunlight. This plant grows best with a half-day of full sunlight from an east- or west-facing window. If that’s not possible, consider growing your Earth star under artificial plant lights.
I’ve recently been growing my bromeliads under this plant light from Amazon and they LOVE it! But any light with an automatic timer and full-spectrum LED light will work. Place your plant under the light and run it for 8 – 10 hours daily for the best results.
Alternatively, if you don’t have an available east- or west-facing window and no access to a plant light, try placing the plant a few feet back from a south-facing window. Just make sure it doesn’t get too much sun, as this can burn the leaves.
Cryptanthus acaulis likes average temperatures of around 75 – 85 degrees F (24 – 29 degrees C) during the day and 65 – 75 degrees F (18 – 24 degrees C) at night.
The best potting soil for Cryptanthus acaulis is one formulated for semi-terrestrial orchids. I personally like and use SunGro Black Gold Orchid Potting Soil. But any high-quality mix formulated for semi-terrestrial orchids will work. (There are mixed reviews on Amazon about this mix regarding its suitability for growing orchids, but trust me – Earth star loves it!)
Re-pot your plant every 2 – 3 years in spring. Choose a wide, deep container with a diameter 2 inches (5 cm) larger than the current pot. A container around 5 or 6 inches (12 or 15 cm) in diameter is more than enough for a mature Earth star.
Be careful when handling Cryptanthus acaulis during re-potting to avoid damaging its sparse, shallow roots.
Cryptanthus acaulis is easy to propagate by separating pups from the parent plant.
This plant flowers when it’s three to five years old. It dies after flowering (like all bromeliads). But as it dies, the plant makes pups – new baby plants that are identical copies of the mother plant. The pups are formed in the nodes of the outermost leaves.
When the pups are about one-third the size of the parent plant, cut them off and pot them in the same potting mix you’re using for the mother plant. Keep them in a clear plastic bag to maintain high humidity levels, put them in a warm place, and leave them there for 4 – 6 weeks until they’re established.
After blooming, the leaves of your Cryptanthus acaulis will begin to flatten out before the plant ultimately dies. Use a clean, sterile pair of scissors or pruning shears to cut the leaves back by about half their length (after flowering is done). This speeds the growth of new pups.
Some Earth stars have completely green leaves, while others feature red, pink, and green stripes. Here are some popular varieties you might want to check out:
- Pink Starlight – Produces a miniature rosette of pink and red striped leaves. This is one of the most beautiful varieties of Cryptanthus acaulis (in my opinion).
- Absolute Zero Tiger – This rare Earth star has a gorgeous white tiger-stripe pattern on the leaves. It looks very exotic!
- Black Magic – This variety has leaves mottled with irregular zebra-like stripes. It looks similar to Absolute Zero Tiger, but it’s darker in color.
Check out Etsy listings for more rare and unusual Cryptanthus acaulis varieties.
Here are some common issues houseplant growers often have when it comes to Cryptanthus acaulis – plus my suggestions on how to fix them.
- Losing Color – If your Cryptanthus acaulis is losing color and leaves begin turning completely green, this is a sure sign that your plant is not receiving enough sunlight. Place in an east- or west-facing window, or grow under artificial plant lights for 8 – 10 hours a day.
- Brown Leaf Tips – If your Earth star develops brown leaf tips, this usually means humidity is too low. Increase moisture in the air by regularly misting your plant, placing it on a humidity tray, or placing near a good quality humidifier.
Here are some frequently asked questions related to Cryptanthus acaulis care that you might find helpful (plus my answers to them).
Does Cryptanthus Need Full Sun?
No, it doesn’t need full sun. But this bromeliad does benefit from a half day of direct sunlight. The best location for Cryptanthus is in an east- or west-facing window, where it receives a half day of morning or afternoon soon. Too much sunlight can burn the leaves.
How Often Do You Water Cryptanthus?
It depends on the time of the year and the humidity level in your home. In general, keep the plant’s small “tank” filled with water. Water the potting soil lightly when it becomes dry to the touch in spring through summer. In fall and winter, water less frequently, but never allow the roots to completely dry out.
Is Cryptanthus a Succulent?
No, Cryptanthus is not a succulent. It is a terrestrial bromeliad (a bromeliad that grows on the ground). Bromeliads are native to South American rain forests. Most grow in the crotches of tree limbs. But some – like Cryptanthus acaulis – sink their roots into the forest floor.
Bromeliads absorb moisture and nutrients from the air through tiny scales in their leaves called trichomes. Many species also produce rosettes of overlapping stiff leaves that create a reservoir to hold water. This “tank” provides the plant with water and nutrients, which are released as insects and debris caught in the water slowly decay.
Where to Buy Cryptanthus Acaulis
I’ve never seen a Cryptanthus acaulis for sale in a local nursery, but I also live in the desert. You may be luckier if you live in a more tropical location. You can always call your local nurseries, garden centers, and plant shops to see if you can find one near you.
If you can’t find one locally, I recommend checking on Etsy. I always buy my exotic and hard-to-find houseplants from Etsy. I like buying from small growers who seem to really care about the quality of their plants and their reputation (as apposed to large online nurseries).
Click here to see the current Etsy listings for Cryptanthus acaulis, and check out all the interesting cultivars available. Good luck and happy growing!