Monday, June 27, 2011

Project 23: Terrarium

Terrariums are fascinating - mini-ecosystems, cramming color and life into a small enclosed glass space. I've been eager to make one but never knew where to start. On a weekend trip to San Francisco, I made time for a terrarium class at Paxton Gate, an eclectic San Francisco shop known for its taxidermied mice - and for its intriguing assortment of classes. Two hours later, I left with a terrarium, and the know-how to make my own in the future.

For this project, we'll be making a succulent terrarium that needs only infrequent watering.

The finished terrarium. 
What you need

  • glass globe terrarium (you can find terrariums online at Paxton Gate or Flora Grubb Gardens)
  • succulents - two to three for a small terrarium as shown here; or more for a larger-sized terrarium
  • active charcoal
  • potting medium for cactus and succulents
  • rocks and stones of varying sizes
  • distilled water
  • small shovel or scoop that can fit inside the terrarium's opening


  • terrarium tweezer (available at Terrain) or extra-long craft tweezers
  • lichens and moss

Some must-haves and nice-to-haves for your terrarium, clockwise from left: potting medium, Spanish moss, river stones, active charcoal, pebbles, another bucket of potting medium, mood moss (at bottom right), reindeer lichen, black lichen
Here's an assortment of succulents. I used echeveria and lithops for this terrarium.
We start with our empty glass terrarium, keeping these long tweezers handy to push in small plants and mosses. This terrarium has a large opening that you can see at the bottom left, and two smaller openings on the upper sides, allowing you to work with it at different angles.
Terrarium and long tweezers
The first thing to put in our terrarium is a half-inch layer of charcoal. The charcoal acts as drainage for the water filtering down through the potting mix, keeping the potting mix from getting waterlogged.
Active charcoal acts as a drainage layer at the bottom of the terrarium
We'll want to fill up as much of this little terrarium as we can with plants and pretty things to look at. To do that, we can angle the soil and plants up from the bottom towards the back, so that they don't spill out of the opening in the front. Here's a view of the back of the terrarium. See how the soil starts to fill up part of the back; it's angled upwards from the front.

Put in less soil than you think you'll need; you can always add in more later. These little terrariums fill up quickly.
Terrarium seen from the back, with soil angling upward.
Once you have an initial layer of soil in, start adding in some mosses. The best part of creating a terrarium is being a landscape architect on a miniature scale. Think about your composition as you add in the plants and mosses.

In the preceding photo, you can see the backside of some mood moss, a thick, clumping, grassy-looking moss. We're using that as a bolster for our composition at the back of the terrarium.

In the photo below, you can see the green mood moss from the front. It makes a lovely background for the silvery succulents. Then, add in a larger rock as another anchor for your composition. In the photo below, you can see a gray stone at the bottom right; I ended up moving it to the back at the top later on.

Time to add in your plants. There's less room in the terrarium than you would think; two or three plants is all that can fit in here. Use the smallest container size of succulent that you can find at your local nursery.

Squeeze the container gently to release the plant, and brush excess soil away from the roots. Carefully place the plant into the terrarium, filling in with extra soil around the plant to cover the roots. Do the same for the other succulents you're using, placing them in a nice composition, with larger ones toward the back and smaller plants toward the front.

Placing moss and succulents.
When the succulents are all placed and the roots are covered with soil, it's time to have fun with mosses, sticks, pebbles, and anything else that would make for a pretty, natural composition. For this terrarium, I added black lichen, which you can see to the right of the terrarium below. The back and sides are enhanced with sprigs of bright green reindeer lichen. At the back on top, there's some Spanish moss. And at the bottom front, you can see assorted colored pebbles. The long tweezers are handy for moving around little pieces of moss and lichen.

There are different things to see from almost any angle of viewing this terrarium. The only part that's not that hot looking is the backside, where we backfilled the soil up at an angle.

Our terrarium's almost done. Now we just need to give it its first watering. Because terrariums are such small, enclosed ecosystems without drainage, the salts and minerals from tap water can be damaging to the plants. You'll want to use distilled water or rainwater to water your terrarium. The easiest way to water a terrarium of this shape is to use a spray bottle or turkey baster, spraying the soil till it's damp. Once it's damp (not soaked), pat it down and settle in the plants more firmly. Wipe any water overspray off the inside walls with a paper towel.

For succulents, you can wait till the soil's dry before watering again.

Place your terrarium in an area that gets sunlight or bright artificial light, but not steady, hot sun - the glass walls magnify the sun's heat and can burn the plants.

And one more terrarium perk: if you want a different composition, you can rearrange the mosses, lichens, and stones for a different effect whenever you like.

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