Selaginella (Spikemoss)

# Selaginella (Spikemoss) — Care and Troubleshooting

Selaginella belongs to the lycophytes, a plant lineage that split off from the rest of the plant kingdom's evolutionary tree over 400 million years ago — older than ferns, older than conifers, and vastly older than flowering plants. Ancient lycophyte relatives once grew as towering trees in Carboniferous-era forests, the source of much of the world's coal deposits; the small, moss-like Selaginella species grown today are the modest, low-growing descendants of that much larger ancient lineage.

Despite superficially resembling true moss, Selaginella is a genuine vascular plant with actual roots, stems, and leaves, unlike true mosses which lack these structures entirely. It forms a dense, feathery, low carpet or trailing mat depending on species and growing conditions, in shades from bright green to some cultivars showing an unusual blue-green iridescent sheen.

An Extremely Narrow Moisture Tolerance

Selaginella shares baby's tears' near-total intolerance of dry soil or air, and arguably takes it even further — this plant genuinely struggles in typical home conditions without supplemental humidity, and is frequently recommended specifically as a terrarium, vivarium, or closed-container plant rather than a standalone houseplant for exactly this reason. Consistently moist (not waterlogged) soil combined with humidity well above normal indoor levels, ideally 60% or higher, is close to a hard requirement rather than a preference.

Light

Selaginella wants low to medium indirect light, reflecting its natural habitat on shaded forest floors and among rocks in damp, low-light microclimates. Direct sun will scorch the delicate foliage quickly, and this is one of the relatively few common plants where genuinely low light is appropriate rather than a compromise.

Common Problems

Crisping and Browning By far the most common Selaginella problem, caused by insufficient humidity or the soil drying out. Unlike some plants that recover from a single dry spell, Selaginella foliage that has crisped typically doesn't green back up, and prevention through consistent humidity and moisture is far more effective than trying to rescue already-damaged growth.

Rot in Overly Wet Conditions Despite wanting constant moisture, standing water or waterlogged, poorly draining soil causes rot, particularly in the dense low growth where air circulation is limited. The plant needs consistent moisture and drainage simultaneously, a genuinely narrow balance to maintain in an open pot without a terrarium environment.

Leggy or Sparse Growth Insufficient light causes thin, sparse coverage rather than the dense mat this plant is known for. Move to a brighter (but still indirect) location if growth seems thin and stretched.

Fungal Issues The combination of high humidity and dense growth that Selaginella needs can also favor fungal problems if air circulation is genuinely stagnant. Some gentle air movement, even from an occasional fan on low in a terrarium setup, helps balance the plant's humidity needs against fungal risk.

Best Grown in a Terrarium or Vivarium

Given how narrow this plant's tolerance is for both moisture and humidity, most successful long-term Selaginella growers keep it in a closed or mostly closed terrarium, glass cabinet, or as vivarium ground cover, where conditions stay stable without requiring constant manual adjustment. A closed glass terrarium is genuinely closer to a requirement than a nice-to-have for keeping this plant looking healthy over the long term outside of a dedicated greenhouse.

Coal, Deep Time, and the Lycophyte Story

The lycophyte lineage Selaginella belongs to has an outsized place in earth's geological history: during the Carboniferous period, roughly 300 to 360 million years ago, giant tree-sized lycophyte relatives such as Lepidodendron formed vast swamp forests, and the compressed remains of those ancient forests are the direct source of much of the coal burned and mined today. Modern Selaginella species are far smaller descendants of that same evolutionary branch, having persisted essentially unchanged in basic body plan for hundreds of millions of years while the giant tree forms went extinct — making a small pot of Selaginella a genuinely direct living link to one of the most consequential periods in the history of the planet's carbon cycle, not just a decorative claim.

Resurrection Species Within the Genus

Some Selaginella species, though not the common S. kraussiana typically sold as a houseplant, are known as resurrection plants for their extraordinary ability to survive near-total desiccation and then fully rehydrate and resume growth when moisture returns, an adaptation seen in species native to genuinely arid rock environments rather than the damp, shaded habitats S. kraussiana comes from. This trait varies enormously within the genus and shouldn't be assumed to apply to the common houseplant species, whose crisped foliage, as noted above, generally does not recover the way a true resurrection species would — a useful distinction for anyone who's read about resurrection ferns and hoped the same forgiveness applied to their houseplant.

Cultivars and Color Variants

A handful of Selaginella kraussiana cultivars are available beyond the plain green species form, including 'Aurea,' with a yellow-gold cast to the foliage, and 'Brownii,' a more tightly mounding, compact form. All share the same fundamental moisture and humidity requirements described above; the cultivar differences are cosmetic rather than functional, so choosing between them comes down to preferred color and growth habit rather than any meaningful difference in care difficulty.

Not a Beginner Plant Despite Its Simple Appearance

The humble, unassuming look of a small mat of Selaginella often leads new plant owners to underestimate how demanding it actually is, expecting something closer to the low-maintenance behavior of a true moss growing wild outdoors rather than the genuinely narrow indoor tolerance it actually has. Anyone considering this plant without a terrarium or similarly humid enclosure already set up should treat it as an advanced-level houseplant experiment rather than a casual, low-effort greenery choice, since its combination of constant-moisture and high-humidity requirements is stricter than the vast majority of commonly sold houseplants.