The name comes from the Latin terra (“earth”) +‎ arium (a place or receptacle). Terrariums are miniature gardens in sealable clear glass or plastic containers.



How do Closed Terrariums Work?

Sealing the containers forms a fully functioning plant ecosystem, mostly self-sustaining with the plants watering themselves through transpiration and condensation.

First let's look at those words:


An ecosystem is a chain of interactions between organisms and their environment. A tiny world that can exist as long as all the right elements are there.


Transpiration is the evaporation (water turning to a vapor) of water through a plant's leaves


Vapor cooling and turning to a liquid.

Now let's look at how the water circulates through the soil, the plants and the air, the water cycle:

Warmth causes moisture to evaporate from the plants and soil, which then condenses on the cooler inside surfaces of the container. Glass is colder than plastic, so it works much better. The water then trickles and drips back down into the soil where it's used by the plants and the process starts again.
Humid terrariums with condensation/mist on the inside of the container are working! 


So if your terrarium looks like the picture, it's a good thing!

It means you've got it right and the water is circulating just like it should.

Where do the plants get their nutrients? in other words, what do the plants eat?

Plants need food like any other living thing and they get this through the soil used when constructing the terrarium. Once established and over months, even years, the dead and decaying plants will add back nutrients into the soil, feeding new growth. 

How long do terrariums last?

A perfectly balanced closed terrarium might last forever!

Choosing a container

Glass is best. Any size or shape will do as long as it fits within the 18" x 18" space allowed for display at the show. It should have no drainage holes and a lid, bung or stopper to make it 'closed'.

Closed is the most important thing

Take a look at the picture. You might be surprised to learn that NONE of the containers are true closed terrariums. If moisture can escape it can't truly have a water cycle. Eventually the plants will need additional water to stop them drying out and dying.

Even the tiny one on top of the books is doomed to fail. Even though there's no hole at the top, the water will drip down onto the books, not only ruining the books but also never reaching the little potted plant. 

What You'll Need and How To Make Your Terrarium

Equipment / Tools

  • Large spoon or garden trowel
  • Small garden snips or scissors for trimming plant roots
  • Spray bottle


  • Glass container with no drainage holes and a top
  • Clean aquarium gravel or small crushed stone
  • Activated charcoal (found at a nursery or pet supply store)
  • Sterile potting mix
  • Live moss and decorative elements are optional
  • The plants


Drainage is important because excess water can kill the plant. So the first layer should be gravel or small rocks. If taken from the garden they should be cleaned well and preferably sterilized.

The main aim of the charcoal is to purify the water, help eliminate any unpleasant odors and also eliminate harmful chemicals that are dangerous and toxic to plants. However, it is not vital. It can also be replaced with dried Sphagnum Moss (also known as Bog Moss), Dried Forest Moss or Green Spanish Moss.

.A layer of moss can also be added after the charcoal layer, it keeps the potting soil from mixing with the activated charcoal and gravel or rocks.

The potting soil can be regular houseplant soil or any commercial one. African violet mix is an excellent soil suitable for terrarium and one can also prepare excellent soil by combining sterilized soil with peat moss and vermiculite in equal proportions.

A layer of live moss will add a 'finished' look to your planting while adding a layer for water retention. Any other decorative items can be used to 'theme' your creation, give it interest and dimension. Let your imagination run wild.

Choosing Terrarium Plants
Choose tropical plants, ferns and mosses. Any miniature, preferably slow growing plant that loves a moist/damp environment. As a beginner, look for those described as 'easy to grow'. Here are a few examples:


1. Variagated Spider Fern     2. Golden Club Moss     3. Black Mondo Grass    4. Aquamarine Piea     5. Peperomia     6. Nerve Plant



Local garden centers that carry supplies:
Bloomin Idiots Floral and Garden Center- Old Forge
Corky’s Garden Path- Scott Township
Creekside Gardens- Tunkhannock
Bold’s Florist- Honesdale
Jerry’s For All Season- Dunmore

Important note: The judge will be looking at the 'closed' terrariums first.

'Open' containers, i.e. dish, bowl, drinking glass, cup or mug etc. will not be disqualified

but will only be considered if there are no closed containers.

Children wishing to enter open containers should enter Category 11 - Succulent and/or Cacti Planter






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