Selaginella Species: The Perfect Terrarium Ground Cover

Selaginella, commonly called spike moss or clubmoss, is not actually a moss at all. These ancient plants are more closely related to ferns and have been around for over 400 million years. For terrarium builders, they offer something unique: the dense, carpet-like growth of moss with the structural interest of miniature foliage.

Why Selaginella Excels in Terrariums

Natural Fit

Selaginella species naturally grow on forest floors in humid, shaded conditions, which makes them perfectly adapted to terrarium life:

• Thrive in high humidity (70-90%)
• Prefer indirect light
• Stay compact and low-growing
• Spread to fill spaces naturally

Visual Appeal

Unlike true mosses, Selaginella has distinct, scale-like leaves arranged in intricate patterns. This creates texture and visual interest that photographs beautifully and adds depth to terrarium designs.

Best Species for Terrariums

Selaginella kraussiana (Spreading Clubmoss)

The most popular terrarium species for good reason.

Characteristics:

• Bright green, feathery fronds
• Spreads horizontally via runners
• Maximum height: 1-2 inches
• Growth rate: Moderate to fast

Varieties:

• 'Aurea' - Golden-yellow foliage
• 'Brownii' - Compact, mounding form
• 'Variegata' - Green and cream variegation

Best for: Beginners, ground cover, filling gaps

Selaginella uncinata (Peacock Fern)

Stunning iridescent blue-green foliage that shimmers in light.

Characteristics:

• Metallic blue-green color
• Trailing growth habit
• Height: 2-4 inches
• Growth rate: Moderate

Care notes: Requires consistent humidity. Color fades in bright light or dry conditions.

Best for: Feature plant, adding color variety

Selaginella martensii (Martens Spike Moss)

Upright growth creates a miniature fern-like appearance.

Characteristics:

• Bright green, upright fronds
• Forms small "trees" over time
• Height: 4-8 inches
• Growth rate: Slow to moderate

Varieties:

• 'Jori' - More compact form
• 'Watsoniana' - White-tipped fronds

Best for: Mid-ground plantings, vertical interest

Selaginella apoda (Meadow Spike Moss)

Native to North America, extremely hardy.

Characteristics:

• Pale green, delicate appearance
• Very low growing (under 1 inch)
• Spreads readily
• Growth rate: Fast

Best for: True ground cover, naturalistic designs

Selaginella lepidophylla (Resurrection Plant)

A fascinating species that curls into a ball when dry and unfurls when watered.

Characteristics:

• Brown when dormant, green when hydrated
• Rosette form, 4-6 inches wide
• Tolerates complete desiccation
• Growth rate: Slow

Best for: Open terrariums, conversation pieces, desert-style builds

Growing Conditions

Light

Selaginella prefers low to medium indirect light:

• Avoid direct sunlight (causes bleaching and crispy edges)
• North or east-facing windows ideal
• Grow lights at 6-12 inches, 8-10 hours daily
• Too little light causes leggy, sparse growth

Humidity

Most species require consistently high humidity:

• Ideal range: 70-90%
• Closed terrariums work perfectly
• Open terrariums need frequent misting
• S. lepidophylla is the exception (tolerates low humidity)

Temperature

Room temperature suits most species:

• Ideal range: 65-80°F (18-27°C)
• Avoid cold drafts
• No tolerance for frost
• Heat above 85°F causes stress

Substrate

Selaginella roots are shallow but need consistent moisture:

• Well-draining but moisture-retentive mix
• Peat-free alternatives work well
• Add sphagnum moss for moisture retention
• Avoid compacted or waterlogged soil

Planting Techniques

As Ground Cover

1. Break plant into small sections (1-2 inch pieces)
2. Space 2-3 inches apart across soil surface
3. Press gently into substrate, do not bury stems
4. Mist thoroughly after planting
5. Maintain high humidity while establishing

On Hardscape

Selaginella can attach to rocks and wood:

1. Select a piece with established roots
2. Wrap roots in damp sphagnum moss
3. Secure to hardscape with fishing line or mesh
4. Keep consistently moist
5. Remove ties once attached (4-8 weeks)

Vertical Surfaces

For background or wall features:

1. Use S. kraussiana or S. uncinata
2. Plant in pockets of sphagnum moss
3. Secure with plant-safe pins
4. Mist daily until established
5. Roots will eventually anchor themselves

Propagation

Selaginella is easy to propagate, which is good because you will want more once you see how it grows.

Division

The simplest method:

1. Remove plant from terrarium
2. Gently separate into sections
3. Ensure each section has roots
4. Replant immediately
5. Maintain humidity while establishing

Stem Cuttings

Works well for trailing species:

1. Cut 2-3 inch stem sections
2. Remove lower leaves
3. Lay horizontally on moist substrate
4. Press lightly into soil
5. Cover to maintain humidity
6. Roots develop in 2-4 weeks

Natural Spreading

In favorable conditions, Selaginella spreads on its own:

• Runners root at nodes
• New plants form along stems
• Can be separated once established
• Guide growth with pruning

Common Problems

Brown, Crispy Tips

Cause: Low humidity or underwatering

Solution:

• Increase misting frequency
• Check terrarium seal
• Ensure substrate stays moist

Yellowing Foliage

Cause: Overwatering, poor drainage, or too much light

Solution:

• Improve drainage
• Reduce watering frequency
• Move to lower light location

Leggy, Sparse Growth

Cause: Insufficient light

Solution:

• Move closer to light source
• Add supplemental grow light
• Prune to encourage bushier growth

Loss of Color (S. uncinata)

Cause: Too much light or low humidity

Solution:

• Reduce light intensity
• Increase humidity
• The iridescent color returns when conditions improve

Design Ideas

Forest Floor Scene

Combine S. kraussiana with:

• Ferns (Asplenium, Nephrolepis)
• Moss patches
• Small stones as "boulders"
• Twigs as fallen logs

Tropical Paradise

Pair S. uncinata with:

• Fittonia for color contrast
• Peperomia prostrata
• Miniature orchids
• Cork bark background

Fairy Garden

Use compact varieties with:

• Miniature figurines
• Pebble pathways
• Small flowering plants
• Decorative stones

Conclusion

Selaginella bridges the gap between moss and fern, offering the best qualities of both. Once established, it requires minimal maintenance while providing year-round beauty. Start with S. kraussiana for reliability, then explore other species as you gain confidence. These ancient plants have survived millions of years because they are remarkably adaptable, and they will likely outlast any other plant in your terrarium.