Cryptanthus is a genus of distinctive bromeliads easily identified by their balas rosette of succulent leaves.
These plants grow anywhere from three inches to three feet tall and have foliage in red, pink, yellow, orange, bronze, silver, and green. The leaves can be serrated or smooth and may have banding, stripes, zig-zag patterns, or patches of differing colors.
The name is Greek for hidden (cryptos) flower (anthos), but it’s the flat leaves that this plant is known for. They grow in a star-shaped rosette pattern, giving this plant the common name “earth stars.”
The flowers are inconspicuous but charming, in a pure white hue.
- Family: Bromeliaceae
- Subfamily: Bromeliaceae
- Genus: Cryptanthus
- Native To: Brazil
- Sun Exposure: Typically bright indirect or diffused light
- Soil Preference: Well-draining loam
- Soil pH: 5.0-6.0
- Blossom Color: White
- Growing Zones: 8-11
Caring for Cryptanthus:
These bromeliads are endemic to Brazil, where they grow on the tropical rainforest floor. Unlike most bromeliads, the plants in this genus are terrestrial and have a larger root system than epiphytic types.
Ideally, keep your plant in an area with temperatures between 60-85°F. In the appropriate humidity, they can survive up to 100°F and down to 35°F, but extreme temperatures will stress the plant.
Most of the plants in this species are exposed to dappled sunlight in their native environment, and you should seek to recreate that in your home. Note that there are some that need direct light or full shade, however.
Find a spot in an east-, south-, or west-facing window with a sheer curtain. Place the plant within a few feet of the window.
Your plant will tell you if it’s in the correct light exposure. Too little light and the leaves will lose color, turning a pale green. Too much light results in large white or yellow spots or yellow, dying leaves.
Plants in this genus need loose, loamy, water-retentive, well-draining potting soil. Look for potting soil that contains a combination of sand, moss, perlite, vermiculite, and loam. The right mix will usually be labeled “water retentive” or “moisture control.”
Unlike other bromeliad genera, which feature plants with cups that can hold and store water, earth stars lack a storage urn. They must be watered at the soil level while taking care not to overwater.
Only add water when the top two inches of soil have dried out.
Earth stars need moderate to high relative humidity between 50-80%. Bathrooms or near the kitchen sink usually have higher humidity than the rest of the house. You can also use humidifiers to raise humidity or grow these plants in terrariums.
Avoid placing them near heat or air vents, which can be drying.
Feed with a mild, balanced fertilizer. If you can’t find something like a 3-3-3 NPK, choose a 5-5-5 or 10-10-10 NPK and dilute it in water by half or fourth, respectively. Use a liquid fertilizer and apply it to the soil, not the leaves.
Fertilizer should be applied once in the early spring, again in the early summer, and once again in early fall. Don’t feed during the winter dormant season.
Choose a container that is about as wide as the foliage. As terrestrial plants, Cryptanthus bromeliads grow more extensive root systems than epiphyte types, so they need a larger container. The pot can be half as deep as it is wide since the roots tend to be wide and shallow.
The material doesn’t matter, though terra cotta tends to dry out more quickly than plastic or metal. The most important thing is that the pot has good drainage.
Best Species and Hybrids
There are dozens of species and hundreds of hybrids within the Cryptanthus genus.
The popular bivattatus species has bi-colored striped leaves. Less popular but equally as decorative is the marginatus species, with light or dark leaf margins. Zonatus plants have small bands of silver on dark green leaves.
Some of the most popular hybrids are ‘Ruby Star,’ which has dark green leaves with bright pink stripes. ‘Absolute Zero’ features nearly black leaves with shiny silver zig-zagging bands. ‘Elaine’ has neon pink margins with a dark green and silver banded stripe down the middle.
Cryptanthus flower one time in their lives, and then they die. Once your plant flowers, it will send out pups or offsets at the base of the plant, the end of the stolons, or at the leaf axis, depending on the cultivar or species. You can replant these pups.
Allow the offset to grow attached to the parent plant until the offset is at least a third of the size of the parent. At that point, cut it away from the parent using a sharp, clean pair of clippers.
Plant the offset in the same type of potting medium you’re growing the parent in. The container should be the same width as the pup. Resist the urge to plant the offset in a larger container, as this increases the risk of root rot.
Common Problems, Pests, and Diseases
Earth stars are fairly tough, but you might encounter mealybugs, scale, and aphids.
Avoid overwatering since plants in standing water are highly susceptible to root rot.