University of Missouri Extension

G6520, Reviewed April 2010

Terrariums

Reviewed by David H. Trinklein
Division of Plant Sciences

A terrarium is a tightly closed, clear glass or plastic container filled with small plants (Figure 1). It also has come to mean an open, transparent container for growing and displaying plants. Terrariums are most useful for small plants that do not adapt well to normal home atmospheres. When properly planted and located, they provide a novel way to grow many plants with minimal care.

Terrarium Figure 1
A terrarium is a good way to keep plants indoors with a minimum of care.
 

Brief history

The use of transparent containers for growing plants dates back at least 2,500 years in Greece. In the United States, terrarium culture is believed to have originated in New England, where housewives placed squawberry (partridge berry) plants in handblown glass bowls.

The invention of the terrarium as we know it is credited to Dr. N.B. Ward, a 19th-century London physician. A plant enthusiast, Ward was interested in growing many types of ferns in his backyard but had not been successful. While studying a sphinx moth emerging from a chrysalis he had buried in moist earth in a closed bottle, he was amazed to see a seedling fern and some grass growing inside. He watched them grow for four years, during which time not one drop of water was added nor was the cover removed.

Ward continued his observations with other plants in containers and, in 1842, published a book called On the Growth of Plants in Closely Glazed Cases. This led to development of “Wardian cases,” which were large, enclosed containers for growing delicate plants in the home or transporting precious plants over long distances. The terrariums most often used today are small ornamental versions of the Wardian case.

Planning a terrarium

Closed, open or dish garden?
The first step in planning a terrarium is to decide whether it will be open (no lid or cover) or closed. Closed terrariums retain the most humidity, followed by open terrariums and then dish gardens. Open terrariums and dish gardens require more frequent watering than do closed, but danger of disease buildup is greater in the latter because of higher humidity.

Containers
A terrarium container should be made from clear glass or plastic. Tinted or cloudy glass greatly reduces light transmittance and interferes with plant growth. As long as it is clear, almost any type of container may be used: an empty fish bowl, fish tank, brandy snifter, old glass jar, jug, bottle. Containers specially designed for use as terrariums are also available.

Closed containers should have transparent covers. Containers with small openings also are quite satisfactory. Containers with large openings without covers can be used but will require more frequent watering to maintain the high humidity needed by some plants. However, open terrariums are drier and less subject to disease. Containers with low sides are suitable for dish gardens and need not be transparent.

Growing medium
The growing medium used in terrariums must be clean, well drained and high in organic matter. A prepackaged peat-lite mix (blend of peat moss, vermiculite and perlite) is an excellent choice. Potting soils sold at garden centers and nurseries where plant supplies are sold are sterilized and ready for use.

Growing medium also can be prepared at home. Mix one part peat moss with one part rich garden soil. Sterilize the mixture by moistening it, covering it with aluminum foil to keep it from drying out while being heated, and placing it in oven at 200 degrees F for about 30 minutes or until it is heated through. The exact time needed depends on the quantity of soil. Using clean tools, spread the soil on clean papers to cool. For planting, the soil should be moist enough to cling in a ball when it is squeezed tightly.

Adding fertilizer to the growing medium usually is not necessary because plants in terrariums should not grow rapidly. If soilless mixes are used or if the soil used is known to be exceptionally low fertility, light fertilization with a houseplant fertilizer may be done after plants are established.

Plants
Decide on a theme for the terrarium: woodland, tropical or desert. When making this decision, consider the temperature and light where the terrarium is to be located. Select plants that suit the location.

Many plants are suitable for growing in terrariums. Plants that have a low and dense growth habit usually are best. Larger plants may be used but must be kept small in terrariums by cutting back the tips.

Don’t mix plants requiring widely different light, temperature and moisture conditions. Succulent plants and cacti are less desirable for terrariums because moist conditions promote rot. Don’t mix desert plants with moisture-loving tropicals.

Table 1 lists some plants suitable for terrarium or dish garden use and describes some of their cultural requirements. Use this table as an aid in selecting plants with similar cultural needs. Plants are listed alphabetically by common name, but because of the variation in and duplication of common names in the plant world, scientific names are included, also. The following points are described in the table:

Tools
Only a few tools are need to plant a terrarium.

Accessories
Rocks, gravel and other natural materials — such as sticks, wood, seedpods and bark — provide pleasing accessories in designing terrariums. Ceramic figures of frogs, mushrooms or snails can help to suggest a natural setting. The accessories added are a matter of individual taste. However, avoid using too many accessories or ones with vivid, unnatural colors. Also, be careful not to introduce insects or disease with the accessories.

Assembling the terrarium

Design
When arranging plants, variation in size, color and texture is desirable. Because terrariums usually are viewed from one side, the growing medium should be sloped for viewing from that side and plants arranged so that taller plants are toward the back. Use rocks, sand, wood and other natural materials to create cliffs, rock ledges, dry streambeds or lush tropical forests. Undulations representing hills and valleys will make the scene more interesting than a flat surface. Sketching a design of the terrarium before actually assembling it can be helpful.

Prepare the container
Before planting, clean and disinfect the inside of the container by washing it with hot, soapy water and rinsing thoroughly. Make sure the inside of the container is dry before planting. If a commercial glass cleaner is used, allow the open container to air for several days before planting.

Add drainage material and growing medium
In general, about one quarter of the terrarium’s volume should be used by the growing medium and drainage material. These can be added easily with a spoon, funnel or other convenient tool.

Drainage
Activated charcoal and pebbles should be placed in the bottom of the container for drainage. These may be mixed together, but the charcoal usually will be most effective in eliminating chemicals that could prove to be toxic to plants if placed in a 1/2-inch layer above the layer of gravel, crushed pots, marble chips or other drainage material. Charcoal is especially important in closed terrariums, which prevent the natural escape of chemicals. Sphagnum moss, placed over the layer of gravel and charcoal, prevents the growing medium from sifting into the drainage area.

Growing medium
Next, add the growing medium. It should be slightly moist so that it doesn’t stir up dust but not so moist that it is muddy and sticks to the sides. For most containers, a minimum depth of 1½ inches is necessary to provide sufficient volume.

Adding plants
Select only healthy, disease-free plants because closed terrariums represent an ideal environment for plant diseases to flourish. If there are disease concerns, enclose plants in a plastic bag and place in bright light for about two weeks before planting in the terrarium. If any diseases are present, they normally will become visible on the foliage or stems.

Before adding the plants, arrange them in an open area about the size of the container to get an idea of relative sizes and textural patterns. A low, coarse-textured plant is often desirable for a dominant focal point near the front. Don’t build a collection of variegated or unusual plants. They compete with each other and don’t create a unified pattern.

To assemble the terrarium, take the plants from their pots and remove extra growing medium to expose the roots. Trim off any leaves that are yellowed or damaged or that show any indication of disease or insects. Trim off some roots from plants that were extremely pot-bound.

Promptly place each plant in the container so that the exposed roots do not dry. In a closed container, try to keep foliage from touching the sides of the container. Leaves touching the glass will collect water and be more subject to decay.

Plants may be placed in deep terrariums using long slender tongs or a stick with a wire loop on the end. Deep containers with small openings will require considerable patience and practice in planting. For such containers, a common practice is to wrap the plant in a piece of paper for protection before inserting it through the small opening. Once the plant is the container, unwrap it and remove the paper. This practice also helps keep the inside of the container clean. Before inserting the plants, dig holes in the growing medium with a pointed stick. After a plant has been placed in a hole, fill in with growing medium and tamp to firm it. A long stick with a cork fixed on the end makes a good tool for lightly tamping the growing medium. After the plants have been positioned, add gravel, sand, moss or other materials to give a finished appearance. Accessories also may be added at this time.

After planting. After planting, mist the plants to wash off growing medium that has stuck to leaves or sides of the container. If the medium was properly moist at planting, heavy watering will not be necessary. The water misted over the leaves is adequate to settle the medium. Don’t cover the terrarium initially. Instead, repeat the misting process after one day. Allow the container to remain open until the foliage is thoroughly dried. Then, if the terrarium is the closed type, apply the cover.

Observe terrarium closely for the first few weeks after planting. Diseases often appear at this time. Any leaves that die or plants that begin to wilt or decay should be removed promptly before the problem spreads to other plants. Root rots often are associated with too much moisture. If rots develop in a closed terrarium, remove the cover to allow more drying. If a fungus seems to be spreading from a plant through the growing medium, it may be beneficial to remove a portion of the medium in the infected area and replace it. Application of a general fungicide also may help to reduce spread of a disease.

In most cases, after a few weeks the terrarium is established and the threat of disease is reduced. Continue to watch for fallen leaves, however, or any plant parts that begin to decay.

Care of the terrarium

Watering
A closed terrarium normally will not need water for 4 to 6 months. The failure of condensation to form on the inside of the container or the presence of wilting plants indicates the need for water. Open terrariums need watering occasionally but not as frequently as other houseplants. A dish garden, unless it is the desert type, will need frequent watering. Waterings must always be light. Because terrariums have no external drainage, heavy waterings result in standing water in the gravel and charcoal, which encourages root diseases. The gravel and charcoal may help overcome occasional light overwaterings, but frequent heavy watering will inactivate the system. When watering a closed terrarium, don’t replace the cover until wet foliage has dried.

Caution
Never overwater. Excess water is almost impossible to remove. Better a little too dry than too wet.

Light
An open or closed terrarium should not receive direct sunlight. However, a dish garden that contains plants needing bright light may be placed in direct sun. Direct sunlight on a closed or a tall, open container will cause heat buildup that will injure most plants. As previously mentioned, most plants suitable for terrariums don’t require extremely bright light but do well in good light. If the terrarium is in a low-light location, supplement with artificial light. A 100-watt bulb placed close to the terrarium or fluorescent tubes placed over the terrarium will be helpful. Supplemental artificial light should be operated 16 to 18 hours a day.

Plants receiving light from a window gradually will face that direction. To keep the terrarium attractive from the desired view, turn it occasionally to keep the plants growing normally.

Pruning
Many plants in a terrarium will gradually outgrow their limited space. A little trimming quickly brings them into bounds and often promotes side-shoot growth that fills out plants. Pinching out tips before plants become too tall results in better growth than severe cutbacks. Be sure to remove all trimmed vegetation from the terrarium.

Fertilization
Because plants in terrariums should not grow rapidly, terrariums seldom need fertilizer. Do not fertilize for at least a year after planting. If after the first year the plants appear yellowish and seem to lack vigor without any other apparent problems, a light fertilization may be necessary. Use a water-soluble houseplant fertilizer at about one-fourth the rate recommended for normal houseplants. Do not allow any of this fertilizer solution to remain on the foliage.

Other care
Although a terrarium is designed for growing plants indoors with minimum care, it is not an inanimate object. Some plants will thrive, and others may die. Occasionally, it will become necessary to remove certain plants or add others. When adding plants, take all precautions described for planting the new terrarium. Adding new problems is always possible when adding new plants.

Table 1
Favorable conditions for plants growing in terrariums.

African violet, Saintpaulia spp

  • 1 to 6 inches high
  • Medium light
  • Open, dish containers
  • Warm temperature
  • Must have good drainage

Airplant, Kalanchoe pinnata

  • Over 12 inches high
  • Medium, bright light
  • Open, dish containers
  • Warm temperature
  • Prefers full sun

Aluminum plant, Pilea cadierii

  • 6 to 12 inches high
  • Medium light
  • Closed, open containers, dish containers
  • Warm temperature
  • Gets leggy in poor light

Ardisia, Coral berry, Ardisia crispa

  • Over 12 inches high
  • Medium light
  • Closed, open containers
  • Warm temperature
  • Very slow grower

Arrow-head plant, Syngonium podophyllum

  • Over 12 inches high
  • Medium light
  • Closed, open, dish containers
  • Warm temperature
  • Fast growing climber

Artillery plant, Pilea microphylla

  • 6 to 12 inches high
  • Medium light
  • Closed, open, dish containers
  • Warm temperature
  • Grows fast, may need pruning

Asparagus fern, Asparagus plumosus

  • 6 to 12 inches high
  • Medium, bright light
  • Open, dish containers
  • Warm temperature
  • Good drainage. Low light causes leaf drop

Baby tears, Helxine soleirolii

  • 1 to 3 inches high
  • Medium light
  • Closed, open containers
  • Warm temperature
  • Vigorous ground cover

Begonia, Begonia spp

  • Over 6 inches high
  • Medium light
  • Closed, open, dish containers
  • Warm temperature
  • Many types

Bird's Nest Sansevieria, Sansevieria trifasciata hahnii

  • 3 to 6 inches high
  • Low, medium, bright light
  • Open, dish containers
  • Warm temperature
  • Very tough plant

Bloodleaf, Iresine herbstii

  • 6 to 12 inches high
  • Bright light
  • Closed, open, dish containers
  • Warm temperature
  • Pinch back occasionally

Bunny-ears cactus, Opuntia microdasys

  • Over 12 inches high
  • Bright light
  • Open, dish containers
  • Warm temperature

Chinese evergreen, Aglaonema spp

  • 3 to 6 inches high
  • Low, medium light
  • Closed, open, dish containers
  • Warm temperature
  • Very durable. Can be cut back

Club moss, Lycopodium spp

  • 3 to 6 inches high
  • Medium light
  • Closed containers
  • Cool temperature
  • Woodland plant

Creeping fig, Ficus pumila

  • 1 to 3 inches high
  • Medium light
  • Closed, open, dish containers
  • Warm temperature
  • Forms dense mat, clings to rough surface

Croton, Codiaeum variegatum

  • Over 12 inches high
  • Bright light
  • Closed, open, dish containers
  • Warm temperature
  • Foliage colorful

Dwarf gloxinia, Sinningia pusilla

  • 1 to 3 inches high
  • Medium light
  • Closed, open containers
  • Warm temperature
  • Very dainty. Keep warm

Dwarf natal plum, Carissa grandiflora nana compacta

  • 6 to 12 inches high
  • Medium light
  • Open, dish containers
  • Warm temperature
  • Easily pruned

Dwarf pomegranate, Punica granatum nana

  • 6 to 12 inches high
  • Bright light
  • Open, dish containers
  • Warm temperature
  • May need pruning, Fruits in bright light

Earth stars, Cryptanthus spp

  • 1 to 3 inches high
  • Medium light
  • Open, dish containers
  • Warm temperature
  • Foliage may be colorful

Emerald Ripple, Peperomia caperata

  • 3 to 6 inches high
  • Medium light
  • Closed, open, dish containers
  • Warm temperature
  • Avoid overwatering

English ivy, Hedera helix

  • Over 6 inches high
  • Medium light
  • Closed, open, dish containers
  • Warm temperature
  • Low, creeping, but will vine upward

False aralia, Dizygotheca elegantissima

  • Over 12 inches high
  • Medium bright light
  • Closed, open containers
  • Warm temperature
  • Needs pruning to keep low

Flame violet, Episcia cupreata

  • 3 to 6 inches high
  • Medium light
  • Closed, open containers
  • Warm temperature
  • Grow as African violet

Foam flower, Tiarella cordifolia

  • 6 to 12 inches high
  • Medium, bright light
  • Closed, open containers
  • Cool temperature
  • Woodland plant

Gold dust dracaena, Dracaena godseffiana

  • 3 to 6 inches high
  • Medium light
  • Closed, open, dish containers
  • Warm temperature
  • Slow growing

Goldfish vine, Columnea microphylla

  • 1 to 3 inches high
  • Medium light
  • Closed, open containers
  • Warm temperature
  • Trailing plant

Haworthia, Haworthia spp

  • 1 to 6 inches high
  • Medium, bright light
  • Dish
  • Warm temperature
  • Best for desert garden

Heart-leaved philodendron, Phildendron scandens oxycardium

  • Over 12 inches high
  • Medium light
  • Closed, open, dish containers
  • Warm temperature
  • Climber or trailer

Hen and chicks, Echeveria spp

  • 1 to 3 inches high
  • Bright light
  • Dish
  • Warm temperature
  • Best for desert garden

Hepatica, Hepatica americana

  • 3 to 6 inches high
  • Medium light
  • Closed, open containers
  • Cool temperature
  • Woodland plant

Impatiens, Sultana, Impatiens walleriana

  • Over 12 inches high
  • Medium bright light
  • Closed, open dish containers
  • Cool temperature
  • Needs pruning to keep low

Irish moss, Selaginella spp

  • 1 to 3 inches high
  • Low, medium light
  • Closed, open containers
  • Groundcover. Likes most organic soils

Jade plant, Crassula argentea

  • Over 6 inches high
  • Bright light
  • Dish
  • Warm temperature
  • Don't overwater. For desert garden

Maidenhair fern, Adiantum cuneatum

  • 6 to 12 inches high
  • Medium light
  • Closed, open containers
  • Warm temperature
  • Dead fronds may need removal

Miniature holly, Malpighia coccigera

  • Over 12 inches high
  • Medium light
  • Closed, open, dish containers
  • Warm temperature
  • Avoid overwatering

Miniature peperomia, Pilea depressa

  • 1 to 3 inches high
  • Medium light
  • Closed, open containers
  • Warm temperature
  • Avoid overwatering

Miniature sweet flag, Acorus gramineus variegatus

  • 6 to 12 inches high
  • Bright light
  • Closed, open, dish containers
  • Warm temperature
  • Grasslike with white stripes

Moss sandwort, Arenaria verna

  • 1 to 3 inches high
  • Bright light
  • Open, dish containers
  • Cool temperature
  • Needs excellent drainage

Nerve plant, Fittonia spp

  • 3 to 6 inches high
  • Medium light
  • Closed, open containers
  • Warm temperature
  • Leaf veins white or pink

Oxalis, Oxalis spp

  • 3 to 6 inches high
  • Bright light
  • Closed, open containers
  • Cool temperature
  • Cloverlike foliage

Panda plant, Kalanchoe tomentosa

  • 3 to 6 inches high
  • Bright light
  • Dish
  • Warm temperature
  • Suitable for desert garden

Parlor palm, Neanthe bella palm, Chamaedorea elegans

  • Over 12 inches high
  • Medium light
  • Closed, open, dish
  • Warm temperature
  • Slow growing

Parrot leaf, Joseph's coat, Alternanthera spp

  • Over 12 inches high
  • Bright light
  • Closed, open, dish containers
  • Warm temperature
  • May be kept compact by pruning

Partridge berry, Michella repens

  • 1 to 3 inches high
  • Medium light
  • Closed, open containers
  • Cool temperature
  • Groundcover

Piggy-back plant, Tolmiea menziesii

  • 3 to 6 inches high
  • Medium light
  • Open, dish containers
  • Warm temperature
  • Small plants grow on old leaves

Pygmy cactus, Rebutia spp

  • 1 to 3 inches high
  • Bright light
  • Open, dish containers
  • Warm temperature
  • For desert garden

Pipsissewa, Chimaphila umbellata

  • 1 to 3 inches high
  • Medium light
  • Closed containers
  • Cool temperature
  • Woodland plant

Podocarpus, Podocarpus macrophylla

  • Over 12 inches high
  • Medium light
  • Closed, open, dish containers
  • Warm temperature
  • Slow growing

Polka dot plant,Hypoestes sanguinolenta

  • Over 12 inches high
  • Bright light
  • Closed, open containers
  • Warm temperature
  • Pinch back to prevent legginess

    Pothos, Devil’s ivy,Epipremnum aureum

    • Over 12 inches high
    • Medium, bright light
    • Closed, open containers
    • Warm temperature
    • Variegated foliage, climbs

Prayer plant, Rabbit's tracks, spp

  • 6 to 12 inches high
  • Medium light
  • Closed, open containers
  • Warm temperature
  • Leaves fold together at night

Rattlesnake plantain, Goodyear pubescens

  • 1 to 3 inches high
  • Medium light
  • Closed containers
  • Cool temperature
  • Woodland orchid

Red bird, Devil's backbone, Pedilanthus tithymalaoides

  • Over 12 inches high
  • Medium, bright light
  • Closed, open, dish containers
  • Warm temperature
  • Foliage variegated

Rosary vine, String of hearts, Ceropegia woodii

  • 1 to 3 inches high
  • Medium, bright light
  • Open, dish containers
  • Warm temperature
  • Low light trailing vine

Sander's dracaena, Dracaena sanderiana

  • Over 12 inches high
  • Medium light
  • Closed, open, dish containers
  • Warm temperature
  • Cornlike plant with white stripes

Satin pellionia, Pellionia pulchra

  • 1 to 3 inches high
  • Medium, bright light
  • Closed, open containers
  • Warm temperature
  • Creeping vine

Spider plant, Airplane plant, Chlorophytum comosum 'Vittatum'

  • 3 to 6 inches high
  • Low, medium light
  • Closed, open, dish containers
  • Warm temperature
  • Forms new plants on runners

Spotted wintergreen, Chimaphila maculata

  • 1 to 3 inches high
  • Medium light
  • Closed containers
  • Cool temperature
  • Woodland plant

Stonecrop, Sedum spp

  • 1 to 3 inches high
  • Bright light
  • Dish container
  • Warm temperature
  • For desert garden

Strawberry begonia, Saxifraga sarmentosa

  • 1 to 3 inches high
  • Medium light
  • Closed, open, dish containers
  • Warm temperature
  • Runners like strawberry

Sundew, Drosera spp

  • 1 to 3 inches high
  • Bright light
  • Closed containers
  • Warm temperature, insectivorous plant

Swedish ivy, Plectranthes australis

  • 1 to 3 inches high
  • Low, medium light
  • Closed, open, dish containers
  • Warm temperature
  • Low, creeping, very durable

Sweet olive, False holly, Osmanthus heterophyllus

  • Over 12 inches high
  • Bright light
  • Open containers
  • Cool temperature
  • Hollylike leaf, may need pruning

Table fern, Victoria fern, Pteris spp

  • 6 to 12 inches high
  • Medium light
  • Closed, open containers
  • Cool temperature
  • Tropical fern

Tahitian bridal veil, Gibasis geniculata

  • 3 to 6 inches high
  • Medium light
  • Closed, open containers
  • Warm temperature
  • Low light creeper or trailer

Variegated ovalleaf peperomia, Peperomia obtusifolia variegata

  • 3 to 6 inches high
  • Medium light
  • Closed, open containers
  • Warm temperature
  • Colorful foliage

Venus fly trap, Dionaea muscipula

  • 1 to 3 inches high
  • Bright light
  • Closed, open containers
  • Warm temperature
  • Insectivorous plant

Waffle plant, Hemigraphis 'Exotica'

  • Over 12 inches high
  • Medium, bright light
  • Closed, open containers
  • Warm temperature
  • Purplish leaves

Watermelon peperomia, Peperomia sandersii

  • 3 to 6 inches high
  • Medium, bright light
  • Closed, open, dish containers
  • Warm temperature
  • Avoid overwatering

Wintergreen, Gaultheria procumbens

  • 1 to 3 inches high
  • Medium light
  • Closed, open containers
  • Cool temperature
  • Woodland plant

G6520, reviewed April 2010

G6520 Terrariums | University of Missouri Extension

Order publications online at http://extension.missouri.edu/explore/shop/ or call toll-free 800-292-0969.

University of Missouri Extension - print indicia