Spike Moss (Krauss' clubmoss) care

Light

Picture the indirect light an east-facing window gives mid-morning — that's the brightness spike moss grows fastest in. Thrives in deep to partial shade with bright, indirect light only. Direct sun scorches the delicate foliage and turns it yellow-brown. An east-facing windowsill, a shaded north window, or a few feet back from a brighter window suits it well; it also adapts to fluorescent or grow lights in a terrarium. You'll know it's right when new leaves come out the same size and colour as the established ones. Smaller, paler new leaves = move closer to the window.

Watering

Aim for keep evenly moist at all times; typically water every 2-4 days so the soil never dries out for spike moss, but treat that as a starting point rather than a rule. A south-facing summer windowsill will dry the pot twice as fast as a north-facing winter room. Lift the pot; if it feels noticeably lighter than it did wet, water it. The soil must stay consistently damp but never waterlogged, as standing water leads to root rot. Never let it dry out, even briefly. Use room-temperature rainwater, distilled, or filtered water where possible, since the shallow roots are sensitive to cold-water shock and mineral build-up.

Soil and pot

Spike Moss grows best in rich, humus-heavy, moisture-retentive mix with good drainage. Use a peat- or coir-based potting mix amended with organic matter to hold moisture, blended with perlite or fine bark so excess water still drains. Slightly acidic to neutral pH (around 5.5-7.0) is ideal. A shallow, wide container suits its spreading, shallow root system. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Spike Moss sits happiest at around 70% or higher humidity and 18-24°C (65-75°F). High humidity is the single most important factor for survival; below roughly 70% the foliage browns and shrivels within days. A closed or semi-closed terrarium is the most reliable way to grow it. Otherwise use a humidifier, a wet-pebble tray, or a bathroom; misting alone is usually not enough. If you keep the room above 18 year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed spike moss sparingly. Feed lightly with a balanced liquid houseplant fertiliser diluted to half strength, roughly every 4-6 weeks from spring through autumn. Avoid over-feeding, which causes brown leaf tips; do not fertilise in winter when growth slows. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on spike moss in the Growli community. Each is annotated with the most common cause so you know where to start.

• Brown, shrivelled or crispy foliage — Almost always caused by low humidity or the soil drying out. Raise humidity to 70%+ (a terrarium, humidifier, or pebble tray) and keep the mix constantly damp.
• Yellowing or scorched leaves — Too much light or direct sun bleaches and burns the delicate foliage. Move to bright indirect light or partial/deep shade.
• Root rot and mushy stems — Result from waterlogged, poorly drained soil with standing water. Keep soil moist but never soggy and ensure the pot drains freely.
• Brown leaf tips — Often from over-fertilising or mineral build-up. Dilute feed to half strength, feed sparingly, and water with rain or distilled water.
• Spider mites and mealybugs — Sap-sucking pests can hide among the dense foliage, especially in drier air. Maintaining high humidity deters them; treat with a mild insecticidal soap if they appear.
• Sudden collapse after drying out — Unlike some plants, spike moss will not survive prolonged drought; even one missed watering can be fatal. Never let it dry out completely.

Propagation

Easily propagated by division of the spreading mat or by laying stem cuttings on damp soil, where they readily root at the nodes; keep cuttings warm and humid until established. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Spike Moss is pet-safe. The ASPCA individually lists Selaginella kraussiana (as "Japanese Moss," family Selaginellaceae) as non-toxic to dogs, cats, and horses. As with any plant, nibbling can still cause mild stomach upset, so discourage pets from grazing. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Spike Moss deep-dive guides

Every aspect of spike moss care, each with its own calibrated guide:

• Spike Moss watering schedule
• Spike Moss light requirements
• Best soil mix for spike moss
• Spike Moss fertilizing guide
• When to repot spike moss
• How to propagate spike moss
• Spike Moss growth rate & size
• Spike Moss cold hardiness
• Spike Moss temperature & humidity
• Is spike moss toxic to cats & dogs?

Related guides

Spike Moss is also known as Spike moss, Krauss' clubmoss, Krauss' spikemoss, African clubmoss, Japanese moss, Trailing Irish moss, and Spreading club moss.

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