It may be the middle of winter but that doesn’t mean we can’t garden. Ever tried miniature gardening indoors? How about making a terrarium? All the best gardening activities are involved—planning the design, choosing the plants, preparing the soil, planting and tending the garden—just on a much smaller scale. Amazingly, terrariums develop their own miniature ecosystems—a closed terrarium even has a rain cycle inside the jar! A miniature garden in a closed terrarium may be just the thing to tide us over until spring.
Whether you choose to make a single terrarium or a whole group of them, terrariums can add greenery and sparkle to your home. I love how my little collection of miniature gardens looks in the early morning light—all shiny and bright!
There are two types of terrariums: open and closed. A closed terrarium is sealed with a lid or cover. I decided to close my terrariums because, although they require a little effort to get established, they require very little care and maintenance going forward. It’s fun and easy to make a closed terrarium. Read on for a list of the supplies and tools you’ll need followed by step-by-step instructions to walk you through the process.
Supplies Needed
. Glass Container: A sizable, clear, transparent container with a lid. Look for interesting forms and shapes. I chose glass apothecary jars with lids for my closed terrariums.
. Suitable Plants: See specifics in Step 2 – Select and Prepare Plants.
. Decorative Elements: See specifics in Step 3 – Plan Decorative Elements.
. Potting Mix: Experts recommend using a good quality, sterile, commercial, soilless potting mix to avoid insect and disease problems. I used Miracle Grow Indoor Potting Mix.
. Water: Use distilled or rain water in a spray bottle or mister.
. Activated Carbon/Charcoal: A layer of activated carbon/charcoal is added to help absorb the odors that can occur when the organic materials begin to decompose. I purchased a container of API Activated Filter Carbon, designed for aquarium filters, at a pet store.
. Stones: A layer of small stones or pebbles is used for drainage. These can be collected from nature or purchased at a garden center. I purchased a bag of Vigoro Decorative Stone River Peebles from a local home improvement store. Wash the stones before use.
. Landscape Fabric: A small piece of landscape fabric, cut to size, is used to prevent the soil from falling into the layer of stones below. Alternatively, fine mesh or screen can be used.
Tools Needed
There are a few tools that will be helpful for assembling the terrarium.
. Pruners: Small pruners or scissors are used to trim plants.
. Paintbrush: A dry, artist paintbrush is used to clean up the terrarium’s walls as well as remove dirt from leaves and decorative elements.
. Tamper: Insert a skewer, chopstick or other long, thin stick into a cork to make a tamper for leveling and tamping down the soil.
. Spoon: A long-handled spoon can be used to scoop and move soil.
. Funnel: The tool I found most useful was also the simplest. A sheet of paper, rolled and taped into a cone shape, became the perfect funnel. It allowed me to gradually add soil in the exact spots it was needed.
. Mister/Spray Bottle
Step 1 – Prepare Container Wash the glass container with mild soap and hot water before use. Avoid the use of strong commercial cleaners.
Step 2 – Select and Prepare Plants The next step is to obtain appropriate plants. Moss and ferns are particularly well suited to the moisture and humidity of a closed terrarium. I admit to a fondness for both (see my previous posts Growing Carpets and Coats of Moss and Southern Ladies, Christmas Stockings and Hairy Armpits). Moss, as I learned while writing that post, doesn’t have true roots, stems, leaves or flowers. It attaches to a surface with its anchoring systems (called rhizoids) and is able to survive by absorbing water and nutrients directly into its plant body. Moss is evergreen, compact and slow-growing. All of these attributes make it the ideal plant for a closed terrarium.
Ferns are also ideal but some species can grow quite large. Care should be taken to choose an appropriate variety. Alternatively, it’s possible to start with an immature plant and plan to monitor and prune it going forward.
A little online research yields a few other plants which are recommended for closed terrariums such as Artillery Plant (Pilea microphylla), Nerve Plant (Fittonia verchaffeltii) and Friendship Plant (Pilea involucrate). See More Info below for a suggested link. Take care to ensure all the plants in a single terrarium are compatible with the same lighting, watering, and humidity requirements.
If you’re lucky, you may be able to collect moss and ferns from your own yard as I was able to do. I simply used a trowel to remove small sections taking care not to remove too much from any one spot. Experts recommend taking no more than 3” squares from each square foot of moss. If you harvest your plants, it’s best to monitor them before planting. I stored my collected moss in clear plastic containers repurposed from the grocery store. I sprayed the plants with distilled water to keep them moist. They remained in these containers for two weeks. I monitored the containers during this time, keeping the plants damp, watching for insects, and removing unhealthy leaves and plants. I assume this 2-week period also helps the plants acclimate to their new environment. You may wish to use a similar monitoring period for purchased plants.
Step 3 – Plan Decorative Elements It’s fun to add decorative elements to a terrarium. A few carefully selected items can add interest to the greenery. Alternatively, a small diorama can be created to add depth, interest and charm. My search for decorative elements led me to the HO scale figures typically used in model railroad scenery. They’re a good size and available in a variety of themes. I purchased 3 sets from Woodland Scenics including Take a Hike (hikers and bird watchers), Windy Day Play (children playing with kites) and Parked for a Picnic (people picnicking).
Interesting stones, small twigs and other natural elements can also enhance the diorama. Small mirrors can be used to simulate a pool or pond. Take care to maintain a consistent scale across all the decorative elements.
Step 4 – Assemble Terrarium After gathering all the supplies and tools, it’s time to assemble the terrarium. It’s a straightforward process of layering materials into the glass jar. The layers are:
. First Layer – Drainage Stones Place a thin layer of stones in the bottom of the jar. These stones are meant to collect any excess water. Some experts say this layer is unnecessary since the terrarium should never contain enough water to require draining. I chose to play it safe and include them anyway. The stones also serve to add interest to the bottom of the jar.
. Second Layer – Landscape Fabric Cut a small piece of landscape fabric to fit on top of the stone layer. Then place additional stones around the outside edge to keep the fabric in place. Here’s how mine looked at this stage.
. Third Layer – Activated Carbon Add a thin layer of activated carbon/charcoal on top of the landscape fabric. The activated carbon can be very fine so use a paper funnel to keep it away from the outside edges.
. Fourth Layer – Potting Mix The final layer is soilless potting mix. I used a spray bottle to moisten the potting mix before adding it to the terrarium. Use a paper funnel to place the soil where it’s needed. The surface does not need to be flat—hills, valleys and slopes can be simulated. I tried to make a hillside by piling more soil at the back of the jar.
Step 5 – Finalize Garden Design It’s best to work out the elements of the terrarium design outside the container. Consider the terrarium’s intended vantage point—will it be viewed from all sides or only from the front? Decide where the moss, or other plants, will be placed. Determine if decorative elements will be added and where. Also, consider the best sequence in which to assemble the elements. For instance, to avoid smothering moss with stones, plan to place the stones first and then tuck the moss around them.
Staging a small scene for a diorama requires a little more upfront planning. HO scale figures are small and their accessories are tiny so manipulating them inside the confines of a glass container can be tricky. I found it helpful to configure all the HO scale elements before putting them into the desired position. Tweezers and poster tack were very helpful for this step. The poster tack locks the tiny parts in place without gluing them permanently.
The diorama that’s evolving in the photo below features a couple having a picnic beside a small pool. The mirror-pool will be surrounded by stones and moss. The small stones, collected from nature over the last few years, have interesting stripes and markings.
Pictured below is a different scene designed for a second terrarium. It features two hikers sitting on top of a rock face. There will be moss at the base of the rock face and ferns in the background. Three small white pebbles will be used to create a stone stack (shown far left). Stacked stone towers, by the way, evolved from rock cairns which were traditionally used for wayfinding. You can learn all about them in my previous post Heaps and Stacks of Stone. The small stones and pebbles were carefully selected from beaches and riversides for their interesting forms and markings.
Step 6 – Add Plants Prepare to plant the moss and plants according to your planned design and assembly sequence. Use the cork tamper to tamp down the soil and remove air pockets. Divide the moss into small sections and place it on the soil around the jar. If using small plants, use the stick-end of the cork tamper to make a small hole, place the plant in the hole, and tamp the soil down around it with the cork.
Step 7 – Add Decorative Elements Carefully place your decorative elements according to your assembly sequence. I started by planting moss around the back of the jar. Then I carefully put the three decorative stones and the mirror-pool into position. I finished by tucking moss around the stones. My final step was to place the picnic figures.
Use a paintbrush to wipe away pieces of dirt and clean up the scene.
Step 8 – Mist and Cover: All that remains to be done is to mist the moss and plants and put the cover in place.
Step 9 – Place, Monitor and Adjust Place the terrarium in a well-lit location with filtered, indirect sunlight. No direct sunlight should hit the glass jar because it will burn the plants.
The objective is to establish a balanced mini-ecosystem, with its own little rain cycle, inside the terrarium. Check the terrarium frequently for the appearance of condensation. Condensation should form on the inside of the glass jar and roll down to water the soil. It should look like a light fog as shown below. If large water drops appear on the glass walls, leave the container open for a while to let the excess moisture evaporate. If no condensation appears, use a mister or spray bottle to gradually add very small amounts (imagine a thimble full) of water.
Once the terrarium is established, it should require very little maintenance. Experts recommend adding water only if the condensation stops, the plants droop, or the soil feels dry. This could be as frequent as every other week or as infrequent as every two months. The moisture requirements of the plants, the nature of the light, the temperature of the room, the tightness of the lid, the growing season, and a number of other factors will affect the terrarium’s ecosystem and water needs. The trick is to monitor it regularly.
If the terrarium container is airtight, experts recommend removing the lid for 5-15 minutes once a week.
As with all gardening, it’s important to be diligent and promptly address any problems with insects or diseased plants.
It’s also important to monitor the light situation over time and across the seasons. I learned this lesson from experience a few years ago. I made a terrarium in the spring and placed it in the indirect sunlight of our kitchen’s bay window. Unfortunately, I didn’t notice the angle of the sun change over the next few months and eventually the rays of the summer sun fell directly on the terrarium. Dang! All the plants were burnt to a crisp!
Step 10 – Enjoy: Now that you’ve finished your terrarium and found the perfect place to display it, it’s time to enjoy your miniature garden! As mentioned at the top of this post, I chose to make several closed terrariums. I display them as a collection for added impact. The variety of shapes and sizes in the apothecary jars adds interest. The repetition of greenery, with moss and ferns in each terrarium, connects the jars and makes the foliage more noticeable.
But the best part, in my opinion, is the hidden worlds tucked away inside these miniature gardens. Each diorama tells a story whether it’s the couple having a picnic beside a forest pool…
… the birdwatchers out for a hike…
… or the hikers enjoying the view after a steep climb.
More Info
Please pin this image to share or save for future reference.
You may also enjoy these previous FanningSparks’ posts:
. Growing Carpets and Coats of Moss is all about using moss in the garden
. Southern Ladies, Christmas Stockings and Hairy Armpits introduces the world of ferns
. Heaps and Stacks of Stone discusses cairns, stacked stones and rock balancing.
I can’t quite recall where I bought my apothecary jars… I’m guessing it was Home Goods. Similar jars can be found online on Target, Amazon and Michaels.
The Garden Helper provides a comprehensive list of Plants Suitable for Growing in Terrariums and Dish Gardens on their website.
Woodland Scenics, as their website explains, “manufactures high-quality products for hobbyists to create realistic model scenery for model railroads, architectural layouts, dioramas, gaming, military models, miniatures and more”.
Today’s Takeaways
.1. A terrarium is a miniature, indoor garden under glass.
.2. Decorative elements and dioramas can add interest and impact to a miniature garden.
.3. Consider gardening in miniature with a closed terrarium of your own.
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