Choosing Plants for Open Terrariums: Design for the Display and the Propagation Container

Open terrariums need plants chosen for dry air and a shallow root run

An open terrarium is a planting container without a lid or with a wide, permanently open mouth. Air moves freely, humidity stays close to room levels, and the substrate is usually shallow. That combination shifts plant selection toward species that tolerate dry air, lean medium and a root zone that dries between waterings. At the same time, the container is a propagation space: it can root cuttings, hold divisions or raise offsets before they move to a permanent pot. The design choice is therefore not just which plants look good together. It is which plants suit the open vessel, and which propagation container design supports the plants you intend to grow in it.

The purpose of an open terrarium as a propagation container differs from its purpose as a display. A display favors slow, compact, visually persistent plants that tolerate the same watering rhythm. A propagation container favors a substrate and layout that allow you to disturb, root and remove young plants without destroying the planting. Deciding which purpose the vessel serves first prevents the common mismatch: a beautiful display that offers no room to lift a rooted pup, or a propagation tray that looks unfinished on a shelf.

Match the plant to the purpose

Open terrariums suit small succulents, certain cacti, air plants, and compact tropicals that tolerate lower humidity, such as some Peperomia and Haworthia species. They do not suit ferns, calatheas, miniature orchids or other plants that need constant humidity and a deep, consistently moist medium. The open vessel cannot supply those conditions, and a lidless container with a shallow substrate is the wrong propagation container for them.

Plants for a display-only open terrarium

• Compact rosette succulents such as Echeveria and Sempervivum hold their shape in bright light and tolerate dry air. They root shallowly and grow slowly, so the planting stays composed for longer.
• Small Haworthia and Gasteria accept a wider range of indoor light than many desert succulents and fit a shallow bowl without crowding.
• Air plants in the genus Tillandsia sit on top of the substrate rather than rooting into it. They suit the open format because they are not competing for moisture in a shallow root run.
• Trailing Peperomia species offer soft foliage and low water demand, though they prefer brighter indirect light than desert succulents.

For a display, choose plants with similar water use and light preference. Mixing a moisture-loving tropical with a desert succulent forces a watering compromise that eventually harms one. The container should be wide enough that each plant sits without pressing on its neighbor, and the substrate should sit below the rim so irrigation water does not spill.

Plants for an open terrarium used as a propagation container

When the container's job is to root plants, the selection criteria change. You want propagation material that roots reliably in a shallow, well-drained medium and tolerates the vessel's ambient air. Suitable options include offsets or pups from rosette succulents, stem sections of trailing Peperomia, and divisions of clumping plants that grow at the surface.

• Succulent pups and offsets root in a drainable, gritty mix and can stay small for months. A wide, shallow container lets you space several pups without deeper root space.
• Stem cuttings from surface-rooting plants root in the same mix and are easy to lift once established. This suits trailing plants that form visible nodes.
• Surface divisions of clumping plants work where the density of the planting is low and you can remove a section without unpicking the whole arrangement.

Avoid planning an open terrarium as a propagation container for plants that expect high humidity to root, such as many tropical cuttings, or those that need deep soil for tuber or bulb formation. An open vessel cannot provide the moist air those cuttings need before roots form.

Container design that supports both growing modes

Openings and reach

The size of the opening controls what you can do inside the vessel. A narrow neck on an open terrarium limits planting to long-handled tools and small, already-rooted plants. A wide mouth allows you to set plants by hand, position cuttings, and lift rooted offspring. If propagation is part of the plan, prioritize a wide opening, even if the silhouette is less dramatic.

Depth and drainage

Open terrariums usually have no drainage hole. That makes substrate depth and particle size important. A shallow layer of gritty, free-draining mix reduces the risk of a saturated root zone, but it also dries quickly in open air. For succulents and surface-rooted cuttings, 5–8 cm of substrate is often enough to root and hold small plants; deeper vessels retain more moisture and suit larger, established plants. Choose a container with a flat bottom and stable footing so it does not tip when you reach in or water.

Materials and weight

Glass and glazed ceramic are common choices. Thin glass is light and needs careful handling when roots are being lifted; heavier ceramic or concrete that does not fit into a shelf with a deep footprint stays put better on a table. Weight matters when the planting is top-heavy or when the vessel will be moved for cleaning.

Separation and access

A display that also serves propagation can be arranged in zones. Use small removable pots or a divided insert sunk into the substrate to hold propagation material separately from the display plants. This lets you remove one rooted pup without disturbing the whole planting. Matching plants to zones avoids mixing a dry-loving succulent with a cutting that needs a more moisture-retentive medium during rooting.

Substrate and equipment for open-vessel growing

An open terrarium runs drier than a closed one, so the substrate does two jobs: it holds just enough moisture for the plants and it drains quickly enough that roots do not sit wet. A gritty mix with a high mineral fraction suits succulents and surface-rooted cuttings; a finer organic mix suits small tropicals that prefer more moisture. Do not reuse spent propagation medium without checking for pests or compaction.

Tools that make a difference:

• Long-handled tweezers place small plants and cuttings into the vessel without crushing the rim or disturbing neighbors.
• A narrow-spout watering can delivers water where it is needed without flooding the surface.
• A small scoop or spoon adds and removes substrate with control.
• Drainage-hole-free watering margin matters: maintain a gap between substrate and rim so water can be poured slowly and absorbed rather than overflowing.
• A divided insert or removable cups turn a display vessel into a practical propagation container.

Buy equipment for the task it performs. Tweezers are useful for planting and lifting rooted cuttings; a divided insert makes propagation easier to manage inside an open display; a gritty mix makes dry-loving plants easier to keep. None of these items guarantees rooting—plant material, temperature and light still control the outcome—but they remove avoidable obstacles.

Light, air and watering decisions

Open terrariums dry faster than closed ones and have no lid to trap humidity. Place them where light matches the plants: bright, indirect light for most compact tropicals and filtered strong light for succulents. Direct sun through glass can overheat the interior. Water slowly and less often than for the same plants in a pot with drainage; let the top of the substrate dry between waterings for succulents and surface-rooted cuttings. For a propagation setup, keep the medium barely moist until roots form, then treat the young plant as you would an established one. The light and watering rhythm in an open vessel is closer to a shallow indoor pot than to a closed terrarium.

Make the choice before you plant

Choose an open terrarium as a display when you want slow-growing, compact plants with similar water use and a stable composition. Choose it as a propagation container when you need a well-aired, well-drained space to root offsets and surface cuttings before they move on. The best container for the second purpose has a wide mouth, a shallow gritty layer, stable footing and a way to remove one plant without dismantling the arrangement. The best plants for either purpose share three traits: tolerance of open air, roots that work in a shallow layer, and growth slow enough to remain manageable in the vessel.