Glass Gardens Northern Gardener November 2013

Orchids thrive in a terrarium with a base of orchid bark and sphagnum moss.

Story and photos by Eric Johnson

Glass Garden Terrariums transport us to another place and, like nature, take care of themselves.

Terrariums are indoor gardening magic. They look and smell like the forest floor brought to your buffet or bedside table. The light-filled orbs and boxes, packed with flora, are a visual treat, like a found nook in a hidden garden. Stick your nose in a thriving terrarium and inhale the damp, sweet, humus smell. It’s intoxicating. Planting a terrarium is a tactile pleasure—a mix of sculpting, digging in the dirt and playing with a dollhouse.

Building a terrarium is fun and easy and once planted, you are left with a tiny, botanical museum piece that asks for little and gives much.

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For a terrarium, you will need a covered jar, pebbles, horticultural charcoal, sphagnum moss and potting soil. Use a small spoon or chopstick to plant. After planting, trim roots to contain growth.

Terrarium 101 You only need a few things to create a terrarium.

Vessel. The container makes the terrarium, so begin with a piece that speaks to you—a container you want in your home for years. Both glass and plastic work, but glass plays best into the organic nature of terrariums. You can find an assortment of containers at nurseries, garden centers, craft stores and even discount stores. Unique pieces can be discovered at thrift or antique stores, or consider using a discarded flower vase—the large ones with globular bases work well. When all else fails, the old standby aquarium or fishbowl are perfect vessels.

A few tips: • The container needs to create an enclosed environment. Containers with larger, more bulbous planting areas and smaller openings (like large vases or fishbowls), keep the moisture level the most consistent.

• If the opening is small enough, you will not need to keep the terrarium covered, but if the shape is cylindrical, you will need a glass cover. If you are drawn to a container that doesn’t have one, glass plates and bowls work. You can also have a glass piece cut at the hardware store, but edge it with thick cellophane tape to dull sharp edges.

• Wash your container well with dish soap to make it as sterile a vessel as possible.

• What sometimes puts people off terrar26

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iums is the idea of the botanical version of a ship in a bottle. Plants growing in a narrow-necked container are dramatic, but I prefer terrariums in a container that is easy to get your hands into—at least for the first one.

Light. Terrariums need bright, yet indirect, light. Some glass containers can actually magnify the sun’s rays, so it is important to avoid direct light; an hour or two of early morning or late afternoon direct sun is OK, but more than a couple hours can fry the plants. Also, the goal is to keep plants at a manageable size, so indirect light helps new growth stay in check.

Temperature. In the average home during the winter, steady, indirect light will keep the enclosed environment at a happy, consistent temperature. Avoid too much heat—for example, on top of a radiator or close to a heating vent or fireplace.

Plants. Moisture-loving plants with low to medium light requirements work best in terrariums. (See page 28 for a list of favorites.)

• Plants that are overachievers, like philodendron, pothos and nephthytis, require extra pruning. A scissors works well and can also be used as tongs to pick up the clippings. For small spaces, nail clippers also work.

• Thanks to the fairy garden trend, tiny plants are more available than ever.

• Leaf and root pruning, much like in the

art of bonsai, preps the larger plants for fitting into their new space. Clip off as many leaves as you can without losing the basic shape of the plant. I have trimmed off as much as half of the root ball without harming the plant.

• You will be surprised how quickly even small plants will fill a container, so purchase or prune plants as small as possible.

• You don’t need to go plant crazy—one beautiful plant and some moss make a striking terrarium.

Soil. The planting base of terrariums is an all-important feature, and there are four levels, from bottom to top: • A 1- to 3-inch layer of pea-sized river rock holds the drained water and looks attractive at the bottom of the vessel.

• A ½-inch layer of horticultural charcoal on top of the rocks assists in drainage and purifies the water, keeping fungus at bay. Don’t skip this step because it also keeps the air in the terrarium pure.

Charcoal can be found at nurseries and garden centers that sell indoor plant supplies as well as at aquarium supply stores.

• A layer of sphagnum moss will help keep the topsoil from leaching into the charcoal and river rock layers. It also has a wonderful, organic look; apply liberally.

• A 1½- to 2-inch layer of sterilized potting soil. Stay clear of soil that has fertilizer; you want to discourage excess growth.

CARRIE ANNE CASTILLO

Right: A tiny holiday terrarium.

Below: Ferns love the humid terrarium environment.

Planting the Garden

Water

When selecting your terrarium’s plants, use the same design principles you use in your outdoor garden. Look for a contrast of textures, sizes, and colors, and pick plants you love.

• Moss (harvested from your backyard if you have it) and baby’s tears create a soft stage for upright fans of feathery ferns and perky, round peperomia.

Hypoestes, prayer plant and nephthytis provide pops of color.

• Orchids love the terrarium environment, though they require a different base than other plants. I have had success with a purchased orchid, planting it in a pocket of orchid bark, surrounded by sphagnum moss, within a layer of potting soil. When the orchid is finished blooming, the leaves remain an attractive element in the terrarium.

• To help plot your terrarium’s design, cut out a piece of newsprint the size and shape of the planting area and arrange your plants to find an arrangement that you like.

• I find a wooden spoon and a chopstick to be good tools when planting. Dig a hole to accommodate the plant’s roots, set the plant into the hole and gently pat the soil around it. Gently shaking the entire container to settle the plants into the holes works well, though don’t be too concerned with leveling the soil: an uneven surface creates visual interest.

The whole idea behind a terrarium is that it supports itself. Moisture released through the soil and the plants keeps the closed environment moist, and the moisture then circulates and re-hydrates the plants.

• After planting the terrarium, gently water all plants, as well as the surface of the soil, with either a turkey baster or a small measuring cup with a pouring spout until ½ inch of water appears at the bottom among the river rock pebbles.

• When necessary, you can mist the sides of the container with a spray bottle or A water the soil at the base of the plants.

Brief History • Condensation on the sides of the of Terrariums glass is the watering barometer. A Terrarium lovers have early 19th century faint, consistent fog, with occaEnglish physician Nathaniel Bagshaw Ward to sional drops on the sides, is thank for their object of affection.

Ward loved plants, perfect and tells you that the as well as moths, and kept chrysalises in sealed jars to terrarium is fine. observe their openings. In one of his jars, he spotted a Consistently larger drops of tiny fern sprouting. water or dripping water off Frustrated by the pollution in London at the time and its the top indicates too much ill effect on plants, Ward created a “fern box,” a small conmoisture; leave the top off servatory-type glass container. The cases—sometimes the terrarium and replace called Wardian Cases—gained popularity for their and check in a day. novelty and decorative value.

• When a terrarium is covered Terrariums experienced a resurgence in popularor has a small opening, expect ity in the 1970s when plant lovers began to it to need light watering no more realize the health benefits than every other month, but once of indoor plants. —E.J. again, monitor the condensation.

Minneapolis-based writer and gardener Eric Johnson writes about gardening at www.gardendrama.com.

Turn page for a list of terrarium plants.

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Terrific Terrarium Plants

Moss Moss turns electric green in the terrarium environment. I harvest my own from a patch in my yard, but it is also available online and at nurseries and garden centers. If you do harvest it, make sure to shake off the garden soil and check for little weeds stowing along. You can never go wrong covering any unplanted soil with moss because it sets a beautiful stage for the rest of the plantings. Nestle and pat it into the soil when planting it.

Ferns Ferns give a woodsy feel to the piece and thrive in the enclosed environment.

Baby’s Tears (Helxine soleirolii) A gentle, soft contrast to the scruffy texture of moss, baby’s tears fries easily in direct sun.

Heart-leaf philodendron

Hypoestes (Hypoestes phyllostachya) Commonly known as polka-dot plant, this favorite outdoor annual is an aggressive grower, but the lower light of the terrarium keeps it in check. It needs pruning but its splashy pops of red and silvery white make it worth the extra TLC. Nephthytis (Syngonium podophyllum) A thriller in the terrarium with its arrowhead-shaped leaves and jazzy colors, it can be an aggressive grower. Plant it in a spot that is easy to access for pruning.

Baby's tears (Helxine soleirolii)

Dracaena deremensis ‘Lemon Surprise’

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Prayer plant (Maranta leuconeura ‘Kim’)

Peperomia magnolifolia ‘Rainbow’

Nephthytis (Syngonium podophyllum ‘Butterfly’)

Prayer Plant (Maranta leuconeura) With strong color, pattern and leaves like paddles, it adds vertical interest to the terrarium.

Peperomia This is a sure-fire terrarium plant with many varieties.

Pilea (Pilea nummulariifolia) The name creeping Charlie sends gardeners running, but this variety is native to South America and is the low-growing shrub of the terrarium. The golden yellow variety sets off other plants to great effect.

Dracaena (Dracaena deremensis) Bulletproof and available in vivid colors, it needs to be tended carefully but loves the humid environment.

Orchids An orchid and some moss are all you need to make a special vessel.

Rex Begonia A plethora of colors and shapes gives the terrarium grower a lot of options, and all are a focal point in the setting.

Begonias do not like their leaves to be wet and prompted me to water at the base of plants, rather than misting.

Hypoestes phyllostachya

Philodendron and pothos Yes, both can take over a small container quickly, but they crawl and trail in a way few terrarium plants do. There are many varieties available. Plant them in a spot that allows —E.J. for pruning.

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