Create a desktop garden for your workspace with this recipe for terrarium success by Melbourne plantist + maker Ms Candy Sparkles.
Originally a must-have in Victorian-era drawing-rooms (known as “Wardian Cases”), terrariums are mini self-contained eco-systems that allow us to enjoy a small-scale slice of nature indoors.
How terrariums work:
With the right balance of moisture, light, warmth, and nutrients, terrarium plants can (as in the instance of the oldest-known sealed “bottle garden”) survive and thrive without fresh air for over forty years.
- A glass container with lid (check the opening is wide enough for your hand to get in)
- Pebbles (for drainage)
- Horticultural charcoal (cleans and filters water/terrarium)
- Dry sphagnum moss (retains moisture away from roots avoiding root-rot)
- Sand (more drainage)
- Soil (African violet mix works well)
- Three different small-leafed ferns with like watering and light requirements. Aim for variety in leaf size, shape and/or colour. Dwarf varieties are perfect for terrariums. Allow for room to grow.
- 1 x water-filled spray gun
- Paper towels
- 1 x (preferably) plastic spoon
- 1 x colander or mesh strainer
Wipe/wash glass container clean. Remember throughout your making session that glass can chip and crack at any stage unless handled with care.
In a colander over your soil shake a cup full of small charcoal fragments to sift the excess charcoal dust (as good as gold dust) onto your soil.
To avoid pooling black water at the base of your terrarium rinse the charcoal until the water running off it is clear – catch this run-off in a bucket for your existing plants.
Rinse pebbles and, along with the charcoal, allow them to dry as much as possible.
Mix 1/2 – 2/3 cup of charcoal fragments into your soil.
Remove plants from their pots gently (fern stems can snap readily and their leaves can bruise from handling). It’s best to hold the pot almost horizontally (over a tub to catch falling soil) – squeeze the sides gently as, with your other hand, you lightly clasp the plant stems close to where they meet the soil and pull the plant out slowly. Gently tap any excess dirt of the roots into your excess soil tub. It’s best to save this soil for a different plant creation as it usually contains styrofoam beads which don’t necessarily look great in your terrarium.
Now is a good time to de-bug – check your plants are caterpillar, slug and bug-free.
About the Layers
Measurements are an estimate as jar size will vary – allow for a final measure of at least one centimeter deep on the layers of pebbles, moss and sand. Aim for soil layer to be at least 1.5x deeper than the root-length of your plants. As you’re layering the ingredients, keep in mind what height you’re aiming for the soil to end up at – where the width of your vessel is the broadest is where you’ll achieve maximum surface area for plants.
Bring on the Zen
Layer at least 1.5cm of pebbles at the base of your jar. Conceal the remaining few small pieces of charcoal at the centre of the pebbles (away from the sides of the glass) so that only pebbles are visible. Charcoal helps keeps your terrarium so fresh and so clean.
With your spray gun lightly mist a handful of sphagnum moss enough so as it compacts without springing back.
Cover the pebbles with a 2-3cm layer of moss – pack it down tightly by pressing down with the backs of your fingers – keep adding moss and pressing down until the desired height is reached (1-2cm).
Ensure that the edge of the moss “net” meets the walls of the glass all the way around (with no gaps at the edges), then spoon your sand in patting it down as firmly as you can. Empty the sand off the spoon as close to the soil as possible so as to keep the glass clean if possible.
Clean-in-between – wrap your fingers in a folded sheet of paper towel, run the backs of them down the inside of the glass to clean it.
Check how your layer of sand looks at eye level. You may want to add more to one side for an asymmetrical look or create wavy patterns.
Spoon your charcoal-laced soil onto the sand. This will be the thickest of the layers to accommodate the root systems of the plants. Pat it down firmly but not tightly.
Again wrap your fingers in paper towel and clean the glass down. Create the shape you want your soil to make around the glass by using the backs of your fingers to press down on it.
Select your shortest plant (planting lowest to highest is easiest) and remove any dead or browning leaves from it. If it’s a crawling fern you can divide it into smaller sections by breaking the soil base like a cookie and gently teasing the roots apart.
Make a hole in the soil near the edge of the glass with the end of a spoon or your finger.
Handling your plant at the base of its stem, place the roots it in the hole, then use your spoon as a mini shovel to re-arrange soil where it’s needed. Firmly pack the soil around the plant.
Repeat with your next highest-growing plant – work on having the shortest plants at the perimeter and tallest at the centre. Leave at least a centimeter between the plants.
Take a quick moment to clean your glass with paper towel.
Plant the tallest fern where the leaves best fit in, factoring for room to grow.
Now for a good drink. Water with a spray gun ONLY – this ensures you will never over-water (and drown) your plants. What is watered cannot be un-watered when it comes to terrariums.
Mist away for this first watering to help establish root growth. Keep spraying until at least the top quarter of the soil looks damp.
Finesse with pebbles, rocks or figurines as you see fit, then wipe the interior of the glass one last time and put the lid on your very own terrarium.
Living with your new friend
Desktop gardens of this variety have a dim disposition – place your plant creation out of direct sunlight (leaves could burn), and where it won’t get too hot (your plant could get cooked). It’ll be absolutely happy on a desk, or even under a desk – think rainforest floor with filtered light. Be sure to occasionally rotate it if it only gets light from one side.
Finding the perfect moisture balance might take a couple of weeks but once you have it right you may not have to spray your plants with water for months.
To assess moisture in the terrarium, note where the condensation comes down to on the glass at the warmest part of the day (this moisture will later “rain” down in the cool of the evening) – it should be less than a quarter of the distance from the top of the container to the surface of the soil. Any less precipitation and you might need to spritz a bit, any more and you might need to remove the lid from the container during the day to allow water to evaporate.
In an over-watering “emergency” wipe away any moisture from the glass interior then layer several paper towels between the lid and the container opening. Position your terrarium somewhere warm but shady and the water vapours being emitted from the leaves will be absorbed into the paper towel instead of recycled.