Plant compatibility: which plants work together in a closed terrarium

Plant compatibility is where most “I bought everything cute” terrariums die. The issue isn’t any one plant — it’s that they need different conditions. Here’s how to match plants so they all thrive.

The three compatibility axes

Any two plants in your terrarium need to agree on:

1. Humidity

Closed terrariums = 90-100% humidity. Most “houseplants” you see at a nursery can’t handle this for long. Even some “tropical” plants need breaks.

Loves closed terrariums (high humidity forever):

• Ferns, fittonias, selaginella, pilea, moss, peperomia, begonias (small varieties)

Tolerates closed but prefers open:

• Some peperomias, certain begonias, ivy (slow death in closed)

Will die in closed:

• Succulents, cacti, most herbs, anything labeled “low humidity”

2. Light

Plants in the same terrarium must all tolerate the same light level. Don’t pair “needs bright light” with “low light tolerant.”

3. Growth rate

This is the sneaky one. Pairing a fast grower with a slow grower means the fast grower will take over within months. The slow grower gets shaded out and dies.

Slow growers (terrarium-friendly):

• Fittonia, small ferns, peperomia, selaginella

Medium growers:

• Pilea, small begonias, moss (yes, moss grows)

Fast growers (careful!):

• Ivy, tradescantia, pothos (terrarium varieties only)
• These need aggressive trimming or they’ll dominate

The matching chart

Here’s a quick reference for the most common pairings:

Plant A	Works with	Avoid pairing with
Fittonia	Pilea, ferns, moss, selaginella, peperomia	Ivy (too aggressive)
Pilea glauca	Fittonia, small ferns, moss	Anything fast-growing
Selaginella	Ferns, moss, fittonia	Peperomia (different humidity)
Small ferns	Anything humidity-loving	Succulents
Moss	Everything humidity-loving	Succulents
Peperomia	Fittonia, pilea, moss	High-humidity-only plants (different needs)

The 3-plant starter combinations

If you want a balanced build:

Combination 1: “Classic green”

• Fittonia (color)
• Pilea glauca (texture)
• Sheet moss (ground cover)

Combination 2: “Forest floor”

• Small fern (height)
• Selaginella (texture)
• Cushion moss (ground cover)

Combination 3: “Color pop”

• Fittonia ‘Red Anne’ (red)
• Pilea glauca (silver-green)
• Selaginella (forest green)

Red flag combinations

Never pair:

• Succulents + anything humidity-loving
• Cacti + ferns (opposite everything)
• Ivy + slow growers (will smother)
• Different humidity needs in a closed jar

How many plants per jar?

A common beginner mistake: stuffing 10 plants into a quart jar. Plants need space. Rule of thumb:

• Quart jar: 2-3 small plants
• Half-gallon jar: 3-5 plants
• Gallon jar: 5-7 plants
• 5+ gallon jar: 7-12 plants

Plant less. They grow.

When to remove a plant

If one plant is thriving and the others are declining, the thriving plant is probably stealing resources (light, water, nutrients). Trim it aggressively or remove it.

The cheat sheet

For your first build, pick 3 plants from the same compatibility group with matching light needs. They’ll work together.

When in doubt, ask in the Discord — describe your jar (size, light) and what plants you’re considering. We’ll tell you if they go together.