Snake Plant
Dracaena trifasciata
Toxic to pets
Frosty Fern
Selaginella kraussiana · Selaginellaceae
Moderate
Pet-safe
Selaginella kraussiana is a low-growing, moss-like vascular plant native to the Azores and sub-Saharan Africa. Despite being commonly sold as 'Frosty Fern' during the winter holiday season, it is neither a fern nor a true moss, but a spikemoss belonging to an ancient lineage of vascular plants. It is particularly prized for its dense, bright green foliage with white-tipped growing shoots that give it a frost-dusted appearance.
☀ Light
Bright, indirect light; no direct sun
💧 Water
Keep consistently moist but not waterlogged
🌡 Temp
10 to 24 C
💦 Humidity
High; above 60% preferred
🌿 Soil
Moisture-retentive, peaty or loam-based mix
🍽 Feeding
Dilute liquid fertiliser monthly in spring and summer
Photo: Chhe at English Wikipedia / Public domain via Wikimedia Commons
How to care for Frosty Fern
Light
Selaginella kraussiana thrives in bright, indirect light. A position near a north- or east-facing window is ideal in the UK, where direct summer sun can scorch the delicate fronds and cause rapid drying. In lower light conditions the plant remains viable but growth slows considerably. Avoid placing it in deep shade for extended periods as this encourages leggy, sparse growth.
Watering
Consistent moisture is essential for this plant's health. The growing medium should be kept evenly moist at all times, but never allowed to sit in standing water, which will cause root rot. Watering from below by setting the pot in a shallow tray of water for 20 to 30 minutes is often the most reliable method, as it avoids wetting the foliage and allows the roots to draw up what they need. In winter, reduce watering slightly but never allow the compost to dry out completely.
Soil and potting
A moisture-retentive yet well-draining compost is required. A mixture of peat-free multipurpose compost blended with perlite or coarse grit in a ratio of roughly 2:1 works well, as does a specialist terrarium or moss compost. The plant does not tolerate dry, free-draining cactus-type mixes. Slightly acidic to neutral pH (around 5.5 to 7.0) is appropriate.
Feeding
Feed with a balanced, diluted liquid fertiliser at half the recommended strength once a month during the active growing season from spring through early autumn. Overfeeding can cause tip burn and damage the fine root system. No feeding is required during winter.
Humidity and temperature
High humidity is arguably the most critical requirement for this plant. It performs best at relative humidity above 60%, making it an excellent candidate for terrariums, bottle gardens, or humid bathrooms with adequate light. Misting the foliage regularly can help but is less effective than raising ambient humidity. Keep temperatures between 10 and 24 C; the plant can tolerate brief cool periods but is damaged by frost. Avoid placing it near radiators, draughts, or air conditioning units.
Repotting
Selaginella kraussiana is a shallow-rooted, spreading plant and does not require frequent repotting. Repot in spring only when the plant has visibly outgrown its container or the compost has become exhausted, typically every two to three years. Choose a wide, shallow pot rather than a deep one, and handle the roots gently as they are fine and fragile.
Pruning
Pruning is not strictly necessary but trimming back wayward or leggy stems in spring encourages a denser, bushier habit. Simply pinch or snip stems back to a healthy node. Removing any brown or dying portions promptly keeps the plant tidy and helps prevent fungal issues. The trimmed stems can be used as cuttings for propagation.
Is Frosty Fern toxic?
Pets: Non-toxic. Selaginella kraussiana is not listed as toxic to cats, dogs, or horses by the ASPCA. However, ingestion of any non-food plant material may cause mild gastrointestinal upset in sensitive animals.
People: Not considered toxic to humans. As with any plant, keep away from young children to prevent accidental ingestion of soil or plant material.
People: Not considered toxic to humans. As with any plant, keep away from young children to prevent accidental ingestion of soil or plant material.
Common problems
Brown, crispy or shrivelling foliage
Likely cause: Low humidity, underwatering, or exposure to dry heat from radiators Fix: Increase ambient humidity using a pebble tray filled with water, a humidifier, or move the plant to a terrarium. Ensure the compost never dries out completely and move the plant away from heat sources.
Yellowing or mushy stems and foliage
Likely cause: Overwatering or waterlogged soil leading to root rot Fix: Allow the surface to dry slightly between waterings and ensure the pot has adequate drainage. Remove any rotten roots, repot into fresh compost, and reduce watering frequency.
Pale, washed-out foliage
Likely cause: Exposure to too much direct sunlight Fix: Move the plant to a position with bright but indirect light, shielded from direct sun, particularly during the warmer months.
Leggy, sparse or etiolated growth
Likely cause: Insufficient light Fix: Relocate the plant to a brighter position, ensuring light is indirect. A grow light on a timer can supplement natural light in darker UK homes during winter.
White powdery coating on foliage
Likely cause: Powdery mildew, encouraged by poor air circulation combined with high humidity Fix: Improve air circulation around the plant, remove affected growth, and if necessary apply a suitable fungicide. Avoid overhead misting late in the day.
Tiny insects on foliage or soil surface
Likely cause: Fungus gnats, which are attracted to consistently moist compost Fix: Allow the very top layer of compost to dry slightly between waterings, use sticky yellow traps to catch adults, and treat the soil with a biological nematode drench if the infestation is severe.
How to propagate
Stem cuttings
Cut healthy stem sections of 5 to 8 cm and press them gently onto the surface of moist compost, pinning them lightly if needed. Keep covered to maintain high humidity and roots should develop within a few weeks.
Division
When repotting, the mat-forming clumps can be gently divided into sections, each with their own roots attached. Pot each division into fresh moist compost and keep in humid, warm conditions until established.
Where Frosty Fern comes from
Native to sub-Saharan Africa, southern Africa, Azores, Canary Islands, Madeira.
Story and origins
The genus name Selaginella is a diminutive of Selago, a name used by the Roman author Pliny the Elder for a plant believed to resemble it. The species epithet kraussiana honours Ferdinand Friedrich von Krauss (1812 to 1890), a German naturalist and zoologist who collected extensively in South Africa in the 1830s and contributed numerous specimens to European herbaria.
Selaginella kraussiana was formally described by the botanist Arthur Braun in 1859, based on specimens collected in South Africa. Its ornamental appeal as a dense, vivid green ground cover was recognised early by Victorian gardeners, who used it extensively in ferneries and decorative glasshouses during the fern craze of the mid-to-late 19th century. More recently it gained widespread commercial popularity as a seasonal novelty houseplant, sold under the trade name 'Frosty Fern' primarily at Christmas time, capitalising on its white-tipped new growth. Its tendency to naturalise freely has led to it being regarded as an invasive species in parts of Ireland, the Azores, New Zealand, and the southern United States.
Varieties to know
Selaginella kraussiana 'Aurea'
A golden-yellow form with lime-green to yellow foliage, particularly vivid in brighter light conditions.
Selaginella kraussiana 'Variegata'
Features green foliage with irregular cream or pale yellow variegation on the stems and leaves.
Selaginella kraussiana 'Brownii'
A more compact, cushion-forming cultivar with tighter, mounded growth; popular for terrariums and bottle gardens.
Fun facts
- Selaginella kraussiana belongs to a lineage of plants that dates back over 300 million years, predating the dinosaurs and related to ancient lycopsids that formed much of the world's coal deposits.
- Despite being marketed widely as a 'Frosty Fern', this plant is not a fern at all; it is a lycophyte, more closely related to clubmosses than to true ferns.
- The plant reproduces via spores rather than seeds, a characteristic it shares with ferns and mosses but not with flowering plants.
- Selaginella kraussiana has become naturalised in many parts of the world outside its native range, including Ireland, the British Isles, New Zealand, and parts of North America, where it can become invasive in mild, moist climates.
- Some species within the Selaginella genus are known as 'resurrection plants' for their ability to survive near-complete desiccation and revive when water becomes available, though S. kraussiana itself is not particularly drought tolerant.
Frosty Fern FAQ
Why is my Frosty Fern turning brown and drying out?
The most common cause is low humidity or underwatering. This plant needs consistently moist compost and humidity above 60%. Place it in a terrarium or on a pebble tray filled with water, move it away from radiators, and ensure you are watering regularly enough that the compost never fully dries out.
Is the Frosty Fern actually a fern?
No. Despite its common name, Selaginella kraussiana is not a fern. It is a spikemoss, belonging to the ancient plant division Lycophyta. Like ferns it reproduces via spores, but it belongs to a completely separate evolutionary lineage.
Can I grow my Frosty Fern in a terrarium?
Yes, and a terrarium is arguably the ideal environment for this plant. The enclosed space naturally maintains the high humidity it requires, and the controlled conditions make it much easier to keep the compost consistently moist without overwatering.
Is the Frosty Fern safe for cats and dogs?
Selaginella kraussiana is not listed as toxic by the ASPCA. It is generally considered safe around pets, though ingestion of plant material could potentially cause mild stomach upset in some animals, so it is still sensible to keep it out of reach of pets that chew plants.
Why does my Frosty Fern lose its white tips after I bring it home?
The white or frosted tips are actively growing shoot tips. If the plant is stressed by low humidity, insufficient light, or temperature fluctuations after being moved from a controlled retail environment, new growth may emerge plain green rather than white-tipped. Providing stable, humid, bright conditions usually restores the characteristic appearance over time.
How often should I water my Frosty Fern?
There is no fixed schedule as it depends on your home's temperature and humidity. The key is to keep the compost evenly and consistently moist. Check it every two to three days by pressing a finger into the compost; if the surface feels at all dry, water it. Watering from below in a tray is a reliable technique.
Can I revive a Frosty Fern that has dried out completely?
It depends on the degree of drying. If the stems are still green but the plant is very wilted and dry, immersing the entire pot in water for 30 minutes and then placing it in a humid environment sometimes allows recovery. If the stems are fully brown and crispy throughout, the plant is unlikely to recover, though cuttings from any surviving green portions can be attempted.
