Karen LaSarge is a writer and graphic designer living in Mobile, Ala. She loves the color green.


Terrariums - Life Under Glass
by Karen LaSarge - posted 11/14/12

Terrariums just wanna have fun. Green moss simulates a golf course while the resident lawnmower man attends to his duties. This container is a shrimp cocktail glass with the glass insert inverted to serve as a moisture-retaining dome.

Rare is the opportunity to dwell in nature as much as we’d prefer, but as gardeners and plant lovers we often find ways to plant inside, frequently in the form of generic houseplants found in local nurseries or gardening sections of large stores. Then there’s the happy moments when we find special plants that can thrive both indoors and outdoors, so we tote them indoors, hoping they’ll adjust to the heat, cold, moisture and light conditions of our dwellings.

As much as I like pots of plants, I often find much more pleasure in the biospheric conditions of terrariums, those miniature greenhouse worlds the Victorians discovered in the early 1800s. The combination of glass, greens and textures has always been a pleasing combination, and even more so when we add bits of rocks, tchotchkes and natural elements to produce an interesting tableau.

Inside an uncovered terrarium is a moisture level higher than what your potted plants live in, and where many plants do very well. Place a lid over it and you have jungle-like conditions that mosses and some ferns adore. It’s these two basic options that give terrariums their low-maintenance conditions; but adjust the container size, number of plants and light conditions and you will get a wider range of options to fit any room of your house.

Many books describe the typical terrarium as a rectangular fish tank or flat-sided goldfish bowl, but there are many other containers which can be used for this purpose.

Larger terrariums are wonderful for stashing a lot of plants, but smaller containers are easier to tuck into a corner or place on a side table or office desk, where lighting might be less than cheerful. It’s these smaller terrariums that oftentimes have the most charm.


How to begin? You’ll need:

• Small bits of charcoal
• Small pebbles
• Potting soil
• Sheet moss or gathered moss from your yard
• A container



B. (Photos A&B) Clumps of pillow moss, surrounded by mica rocks with accents of lichens, stay moist with a simple cake dome. With the dome set on top of the rocks, the moisture level is kept just right.


D. (Photos C&D) A terrarium within a terrarium: Silver lace fern (Pteris ensiformis) surrounded by a simple layer of sheet moss frames a small pottery urn holding a miniature glass bottle filled with a tiny clump of moss.



F. (Photos E&F) Showcasing a variety of shapes and sizes, this ball-shaped glass contains a variegated African violet, a button fern (Pellaea rotundifolia) and a small, variegated Victorian brake fern sprout (Pteris cretica 'Albo-lineata'), surrounded by mica rocks and lichen.

G. With the proper balance of light, moisture and air, this orchid has happily resided in this glass vase for a month.

While the ingredients are pretty mundane, the container which will show off your choice plants is where you can have the most fun. Look around for the odd glass vase or hurricane chimney and then spread out your haul. Turn them on their sides or upside down to find an interesting approach to your display.


Containers I have used:

• Shrimp cocktail glass
• Glass battery jar
• Globe-shaped serving bowl
• Slender tall vase
• Large glass plate
• Cake dome
• Flat glass candle holder
• The usual cloche


Miscellaneous elements to add:

• Mica rocks
• Lichens
• Pine cones
• Acorns


Once you’ve decided what container to use, determine how much moisture your container will provide. This will depend on the ventilation. A lid will promote high humidity while an open container provides less, depending on the depth and size of the opening.

Humidity will also depend on where you place your terrarium –  light will intensify condensation on closed containers, so experiment if needed.

Plants which can tolerate higher humidity:

• Ferns, but not all
• Mosses
• Selaginellas
• Gesneriads
• Soleirolia soleirolii (baby’s tears)


Plants for lower humidity:

• African violets
• Bromeliads
• Begonias
• Orchids
• Peperomias
• Pileas
• Episcia (flame violet)
• Ivy


Determine what you want to plant and how many. I keep mine simple, never crowded, to allow room for plant growth as well as rocks, moss and interesting elements. Remember that some plants may get larger than your terrarium, so clipping may be necessary.

To begin assembly, line your container with about a 1- to 2-inch layer of pebbles, then scatter charcoal chips over the pebbles. The charcoal will keep excess water from becoming stagnant and developing fungi. If it’s a deeper container, the next layer should be sheet moss for extra moisture absorption.

Add the potting soil, keeping it deep enough for plant roots, but low enough to keep the plants from overreaching the top.

Add your plants, then your moss, and then play with the decorative elements. Varying the textures, shapes, surface and colors will give your terrarium a rich and inviting look.

If the container has a cloche lid, go vertical with extra containers by stacking them. Remember to create a display that accents the plants or elements, and use the shape of the container to play off the interior scenery. Once you’ve practiced and found what works, you can make great gifts that people will love.


Watering and Care

Some enclosed containers may not need watering for weeks or months, while unlidded containers may need it once a week. Test the soil for moisture content when you’ve assembled a new terrarium and water lightly when needed.

If mold occurs, remove the lid, let it dry out and reduce the amount of water. Wipe any mold off the plants and remove any dead, water-soaked leaves. You may need to keep the lid off for a week or so.



Plants in terrariums should not be placed in direct sun since glass will magnify the light and scorch the plants. Keep away from heating sources as well.


What Not To Plant

Sun-loving plants such a herbs, cacti and succulents do not tolerate the terrarium lifestyle and may thank you for your efforts by dying.

Have fun with your terrariums and if one plant doesn’t adjust, remove it and try another. Some plants, such as African violets, have blossoms that can not tolerate high humidity, so simply remove them when needed. Go zen and create one filled with green moss and a favorite stone, or find a figurine you like and build a terrarium world for it. Start simple and work to complex. Or start simple and stay simple. There are no boundaries for having fun with terrariums and no end to the possibilities. In the end, you’ll have a small bit of nature residing all year long, waiting to bring you delight.


Recommended Reading

The New Terrarium by Tovah Martin


(Photos by Karen LaSarge.)


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