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GARDEN TIPS – Written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Written December 13, 2015

Trends, including gardening trends, have a way of recycling themselves. Creating terrariums, an old trend from the 70s, is popping up again.

Terrariums were first a utilitarian item created by Dr. Nathanial Ward, an English physician and botany enthusiast, for germinating ferns from spores. He created a closed glass case, named the Wardian case, that was pretty much a miniature greenhouse. The case proved very useful to plant collectors wanting to bring plants back to England from far away places and also became popular in home decorating.

The large glass terrarium in my garage is proof that I enthusiastically participated in the terrarium trend of the 70s. Terrarium purists will tell you that a terrarium is planted in a transparent closed container. Not long ago I talked about miniature dish and fairy gardens. A terrarium is similar, but the “garden” is placed inside a clear container, such as a large glass jar, big bottle, fish tank, or giant goblet. Clear plastic containers may also be used.

I recommend a container that is large enough to accommodate the plants you choose to grow and one that has a large enough opening to facilitate planting the terrarium. If the opening or neck of a container is narrow, planting within them is like trying to build a ship in a bottle, possible but difficult.

Start by cleaning the inside of your container and when dry, add “soil” to the container. Use an artificial potting mix, preferably one containing primarily peat moss, perlite, and sand. There is no need to add gravel or other coarse material for drainage as recommended in the 70s, as these materials actually hinder drainage.

Moisten the mix first because it is difficult to moisten once it is in the container. How much mix is needed? There should be enough mix to accommodate plant roots, but generally it does not need to be any deeper than three inches even in large containers.

Finding and selecting suitable plants for your terrarium may be a challenge. Seek out dwarf and miniature plants that will stay small or slow growing ones that will not outgrow the container quickly. Select ones that are similar in their growing requirements, such as humidity, light, and soil moisture. Plants of varying heights, texture, and leaf color will provide the most interest in your design.

When you are ready, remove the plants from their pots and loosen the roots. Plant the largest and tallest plants first and then arrange the smaller plants around them to provide a pleasing “landscape” design. The plants will grow, so take care not to use too many or place them too closely together. Moss or prostrate trailing plants can make attractive ground covers. If desired, add some decorative accents such as small rocks or figurines.

After finishing your planting, rinse any potting mix off the container sides and plant leaves using a spray bottle, taking care not to add too much water. Place the lid on the container or use clear plastic wrap to close it up. Situate the terrarium where it will get lots of light but no direct sunlight.

Your terrarium may exhibit considerable condensation. However, if the condensation is excessive or continues past a week or two, vent the container a little each day until it stops. After that you may need to water occasionally and prune plants when they start to grow too large, but you should be able to enjoy your terrarium without constant attention.

My favorite plants for a terrarium? They are miniature African violets and their relatives, miniature Gernerias.


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Are you old enough to remember the “green revolution” of the 1970

s when live houseplants were popular? Veritable jungles grew in homes across the county.

While many grandmothers had perfected the indoor growing of African violets, the public wanted more choices. Universities researched the types of plants that could be grown under the low level of light found in buildings. They also developed soilless potting mixes that provided better growth than plain unsterile garden soil. Garden writers wrote book after book on the care of houseplants. An entire indoor plant industry was “sprouted” and there were live plants growing in shopping malls, office buildings, and homes. The more plants, the better.

So why have homes and businesses shifted from their tropical plant decor of the 70s and 80s to a paucity of live plants today? I don’t know, but I can guess some of the reasons. Houseplants take effort and time, both precious commodities with today’s very fast paced lifestyles. Houseplants can be messy with dead leaves, repotting, and water leaking from pots. If not nurtured and provided with enough light, houseplants can turn into downright ugly or dead specimens.

In the late 1980s, when the indoor plant craze had started to wane, NASA research revealed the ability of certain indoor plants to help purify air by removing harmful organic pollutants. Because of the energy crisis and the skyrocketing costs of heating and cooling, more and more homes were being built to be energy efficient. The more energy efficient the homes, the greater the buildup of these harmful organic pollutants of trichloroethylene, benzene, and formaldehyde.

These pollutants were given off by the various adhesives, building materials, foam insulation, paint, and other finishes used to construct furnish, and clean our homes. While the standards for many of our building materials and paints have changed to reduce our exposure to these air pollutants, they’re still present in our homes.

When NASA research revealed that certain indoor plants could help “clear the air,” it was presumed that it was the green leaves that did all the work. Later research revealed that it was the plant, the roots, and the soil working together. For plants to be most effective as air purifiers, it’s desirable to “maximize air exposure to the plant root-soil area.” (Researchers noted that even better results could be obtained if fans with charcoal filters were used to pull air into the soil. )

The general recommendation based on the NASA research is to place at least 15 adequately sized houseplants (plants in six to eight inch or larger pots) in a 1,800 square foot house. The plants found to be most effective at cleansing polluted indoor air are (Aglaonema modestum) Chinese evergreen, (Chamaedorea sefritzii) bamboo or reed palm, (Chlorophytum comosum) spider plant, (Dracaena deremensis) Janet Craig or Warneck dracaena, (Dracaena fragrans `Massangeana

) cornstalk dracaena, (Dracaena marginata) red-edged dracaena (Epipiremnum aureum) golden pothos, (Ficus benjamina) weeping fig, (Hedera helix) English ivy, (Philodendron domesticum) elephant ear philodendron, (Philodendron scandens `oxycardium

) heartleaf philodendron, (Philodendron selloum) selloum philodendron, (Sansevieria trifasciata) snake plant, and (Spathiphyllum) peace lily. While not year-round houseplants, potted mums and gerbera daisies were also very effective as air purifiers.

So go green, start a jungle in your house and clear the air.

Published: 11/14/2009 12:23 PM



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