Choosing what plants are best for a terrarium often feels overwhelming when you’re staring at endless plant varieties at the nursery. The miniature world inside glass containers creates unique growing conditions that differ dramatically from traditional houseplant care, leaving many enthusiasts questioning their plant selections.
During my six years of building terrariums, I’ve witnessed countless beginners struggle with this fundamental question. The confined space, humidity levels, and limited airflow of terrariums require specific plant characteristics that not every green beauty can handle—much like how beavers select only the right materials for their dams.
Our question of June is: Is labradorite safe to use in damp terrariums?
What plants are best for a terrarium?
The best terrarium plants are slow-growing species that thrive in high humidity environments while tolerating limited space and indirect light. These plants typically include small ferns, mosses, air plants, small succulents, and compact tropical species that won’t outgrow their glass homes.
Understanding terrarium environments
Terrariums create distinct microclimates that determine plant success. Closed terrariums maintain 80-90% humidity levels and experience minimal temperature fluctuations, while open terrariums offer moderate humidity around 40-60% with better air circulation. The glass walls filter and diffuse light, creating bright but indirect illumination that many tropical understory plants prefer.
Soil moisture remains consistently higher in closed systems due to the water cycle effect—condensation forms on glass walls and drips back into the soil. This environment mimics tropical forest floors where many suitable terrarium plants naturally occur.
Top plants for closed terrariums
Small ferns excel in closed terrarium conditions. Maidenhair ferns (Adiantum), button ferns (Pellaea rotundifolia), and baby tears (Soleirolia soleirolii) thrive in the humid, stable environment. These species naturally grow in moist, shaded areas and adapt well to the limited root space.
Mosses serve as excellent ground cover and humidity indicators. Sheet moss, cushion moss, and mood moss establish quickly and help maintain moisture balance. They require minimal soil depth and actually prefer the consistent dampness that might harm other plants.
Small tropical plants bring color and structure to closed terrariums. Nerve plants (Fittonia), small prayer plants (Maranta leuconeura), and miniature orchids like jewel orchids (Ludisia discolor) provide interesting foliage patterns while staying compact.
Air plants (Tillandsia) work well when mounted on driftwood or decorative elements. They absorb moisture from the humid air and don’t require soil, making them perfect for creative terrarium designs.
Best plants for open terrariums
Small succulents dominate open terrarium gardening due to their drought tolerance and compact growth. Haworthia, small echeveria varieties, and string of pearls (Senecio rowleyanus) handle the drier conditions while maintaining interesting forms and textures.
Small cacti thrive in open terrariums with proper drainage. Barrel cacti, pincushion cacti, and small paddle plants (Kalanchoe) provide striking architectural elements without requiring frequent watering.
Mediterranean herbs like small rosemary varieties, thyme, and oregano bring fragrance and practical value to open terrariums. These plants appreciate the good airflow and moderate moisture levels.
Plants to avoid in terrariums
Fast-growing plants quickly overwhelm terrarium spaces. Pothos, spider plants, and most philodendrons will outgrow containers within months, requiring constant pruning that disrupts the ecosystem balance.
Plants requiring full sun struggle in the filtered light conditions of glass containers. Most flowering annuals, vegetables, and fruit plants need more direct sunlight than terrariums can provide.
High-maintenance plants with specific watering requirements often fail in terrarium environments. Plants sensitive to overwatering or those requiring dry periods between watings clash with the consistent moisture levels in closed systems.
Choosing plants based on terrarium size
Small terrariums (under 6 inches) work best with single specimens or very small combinations. Individual air plants, small haworthia, or a single small fern create beautiful focal points without overcrowding.
Medium terrariums (6-12 inches) allow for layered plantings with 2-4 plant varieties. Combine a small fern with moss ground cover and a flowering accent plant like a small African violet.
Large terrariums (over 12 inches) accommodate complex ecosystems with multiple plant types, varying heights, and diverse textures. These systems can support small trees like Ming aralia or Norfolk pine alongside understory plants and ground covers.
Sourcing and preparing terrarium plants
Purchase plants from reputable nurseries that label plants clearly and maintain healthy stock. Inspect plants carefully for pests, diseases, or signs of stress before bringing them home.
Quarantine new plants for 1-2 weeks before adding them to established terrariums. This prevents introducing pests or diseases that could devastate closed ecosystem environments.
Clean plant roots gently and trim damaged portions before planting. Remove old soil to prevent introducing unwanted organisms or incompatible soil chemistry to your terrarium mix.
Conclusion
Last month, I helped a neighbor select plants for her first closed terrarium after her previous attempt failed with incompatible species. We chose a small maidenhair fern, cushion moss, and a tiny nerve plant—all thriving beautifully in her kitchen window four weeks later. This success story reflects the careful plant selection process that transforms glass containers into flourishing miniature ecosystems, proving that understanding plant needs creates the foundation for terrarium mastery.
El Castor is your exclusive terrarium guide.