Build Your Own Terrarium: A Miniature Garden Under Glass

A terrarium is a miniature garden enclosed in glass, creating a self-sustaining microclimate that can thrive with minimal maintenance for months or even years. The concept dates back to 1842 when botanist Nathaniel Ward accidentally discovered that fern spores could grow in a sealed glass jar, giving rise to what we now call the Wardian case. These early terrariums revolutionized plant transport, allowing exotic species to survive months-long sea voyages by maintaining their own humidity and water cycles inside sealed glass containers. Today, terrariums have experienced a massive resurgence in popularity because they combine the beauty of a living garden with the low-maintenance appeal of a houseplant, all contained in an elegant glass vessel that serves as living art for desks, shelves, and tabletops.

The type of terrarium you build determines which plants will thrive and how much ongoing care is required. Closed terrariums create a humid, rainforest-like environment where moisture recirculates continuously — water evaporates from the soil and plants, condenses on the glass, and drips back down, creating a self-sustaining water cycle. They are perfect for ferns, mosses, fittonias, prayer plants, and other tropical species that love high humidity. Open terrariums allow air to circulate freely and moisture to evaporate, making them suitable for succulents, air plants, cacti, and other drought-tolerant species that would rot in the humid environment of a sealed container. Choosing the wrong plants for your terrarium type is the most common reason terrariums fail.

The Enchantment of Terrariums

Open vs. Closed Terrariums

Building Your Terrarium: The Layering System

Proper layering is essential for drainage and prevents root rot in the enclosed terrarium environment:

• Layer 1: Gravel or small stones (one to two inches) at the bottom for drainage — this prevents roots from sitting in standing water
• Layer 2: Activated charcoal (half inch) to filter water naturally and prevent musty odors from developing in the sealed environment
• Layer 3: Sphagnum moss barrier to prevent the potting soil from washing down into the drainage layers below
• Layer 4: Potting soil appropriate for your chosen plants (two to three inches) — use regular potting mix for closed terrariums and cactus mix for open ones
• Layer 5: Plants arranged with the tallest in back and smallest in front for the best visual depth and composition
• Layer 6: Decorative elements like pebbles, miniature figurines, driftwood, or crystals for personalization and visual interest

Best Plants for Closed Terrariums

These moisture-loving plants thrive in the humid, self-sustaining environment of a sealed glass container:

• Nerve Plant (Fittonia) — Colorful veined leaves in pink, white, or red that love the constant humidity and compact growing space
• Moon Valley Friendship Plant — Textured leaves with a compact, bushy habit that stays small and lush in enclosed spaces
• Baby Tears (Soleirolia) — Creates a lush, moss-like carpet effect across the terrarium floor, filling gaps between larger plants
• Maidenhair Fern — Delicate, fan-shaped fronds that need constant moisture and absolutely thrive in high-humidity environments
• Selaginella — Club moss that forms a dense, fern-like mat and prefers the consistently moist conditions only a closed terrarium provides
• Pilea Glauca — Tiny leaves on delicate red stems that create a beautiful cascading, fairy-garden effect

Best Plants for Open Terrariums

These drought-tolerant plants do well in the drier conditions of an open container with good air circulation:

• Haworthia — Compact, slow-growing succulent with architectural form and striking white-striped patterns
• Echeveria — Rosette-shaped succulents available in a rainbow of colors from powdery blue to soft pink
• Air Plants (Tillandsia) — No soil required at all; attach to driftwood, stones, or decorative elements inside the terrarium
• String of Pearls — Trailing succulent that cascades beautifully over the container edge, creating a waterfall effect
• Jade Plant — Miniature tree-like succulent with thick, glossy leaves that adds a sculptural element to the arrangement

Maintaining Your Terrarium