One fine day when I was in primary four, I learnt of the existence of bottled gardens in Science class. Since then I have been thoroughly fascinated by them; they are like portable miniature forests! I tried finding as much information on them from gardening books and magazines (life pre-internet was so different!). I didn't have the courage to make one until 7 years ago. I started out with a clean glass container and collected lots of moss from a nearby park. It died a quick death (RIP terrarium number 1, life span of 2 weeks).
Healthy and thriving terrarium
Long story short, I never gave up, killing many many plants in the learning process. I now have a thriving, healthy collection of fern and moss terrariums of up to 1+ years old, achieved through lots of reading, and trial and error. So here are some points to get started:
- BASICS
Let's start with some key ingredients:
- a reasonably sized container (can be open or closed)
- drainage layer of pebbles/rocks
- filter layer (sphagnum moss/flyscreen)
- activated charcoal
- substrate (clean soil/propagating sand)
- plants!
- decorative pebbles/shells/fossil/figurines (non-compulsory but makes it look good)
Tools required:
- skewers/tweezers to move plants, decor etc in a small container where your hands can't fit
- soft bristle paint brush to clean dirt off plants
- water spray bottle to wet down soil and clean the plants and containers without drowning them
- small trowel/funnel to neatly move soil into the container
The basic step-by-step process is:
1) Have about 10-15% depth clean drainage pebbles in container:
You don't want the soil or the plants to be constantly sitting in stagnant water (eewww)
Medium sized pebbles for drainage
2) Add filter of sphagnum moss or flyscreen:
This is to stop the top soil layer from mixing in to the drainage layer
I used both sphagnum moss and flyscreen for filter layer here
Sphagnum moss takes up too much space for such a small terrarium but I like the look!
Besides, if conditions are right, the brown sphagnum moss can come back to life!
(see the star shaped moss in the north-west rim of the bottle is now green and growing)
3) Add fine layer of activated charcoal:
This helps to keep water in the closed system 'clean', it also removes odour. I get mine from
Daiso but they are also available from nurseries and aquarium shops
Daiso but they are also available from nurseries and aquarium shops
4) Add about 10-15% depth of soil:
Self-explanatory, you need soil for most plants to grow in but make sure they are sterile! I use
fast draining succulent potting mix but I hear propagating sand works well too
fast draining succulent potting mix but I hear propagating sand works well too
5) Arrange your plants
6) Water the plants in
7) Decorate with pebbles, fossils, shells, mini figurines etc
In summary it should look like this:
A terrarium in layers
But that's just the beginning!! A few things need to be considered to make sure your terrariums are successful. Let me explain the finer details:
- ENCLOSED SYSTEM
Whether the terrarium you choose to make is open or closed, the environment is pretty much self-sustaining. This means that what you choose to add in the beginning has to be super healthy and clean. Any critter, mold, pest or chemical that hitched a ride with the soil, rocks or plants are gonna stay in there for a very long time and may not be good for the micro-ecosystem. It also pays to make sure the added decorative items are water resistant or at least sitting off the soil otherwise they can encourage rot due to the high humidity (if pine cones and drift wood are used they should stay dry). The soil and sphagnum moss needs to be clean and sterile (store bought is good), and rocks and plants to be washed.
This step is especially important for moss and plants collected from the wild as the soil normally harbours lots of fungus spores, worms, and insects along with their eggs. You DO NOT want a population explosion of any of THOSE in your terrarium (ew!). I have made a habit to quarantine any moss I collect for at least a month by storing them in a ziplock bag in the fridge (make sure you get permission from everyone sharing the fridge :p). I occasionally encounter weed seeds stowaways amongst the moss too. They start to sprout in the fridge so I can rid of them before planting. I once had a large number of gnats (about 30), 2 millipedes, and a small snail making their homes in my terrarium because I did not quarantine or wash my plants. They wrecked havoc on my maiden hair fern terrarium and I had to chuck everything out :( When things get that bad, it's best to start over.
This step is especially important for moss and plants collected from the wild as the soil normally harbours lots of fungus spores, worms, and insects along with their eggs. You DO NOT want a population explosion of any of THOSE in your terrarium (ew!). I have made a habit to quarantine any moss I collect for at least a month by storing them in a ziplock bag in the fridge (make sure you get permission from everyone sharing the fridge :p). I occasionally encounter weed seeds stowaways amongst the moss too. They start to sprout in the fridge so I can rid of them before planting. I once had a large number of gnats (about 30), 2 millipedes, and a small snail making their homes in my terrarium because I did not quarantine or wash my plants. They wrecked havoc on my maiden hair fern terrarium and I had to chuck everything out :( When things get that bad, it's best to start over.
Stoopid millipede tearing up my beautiful moss
Some forums suggested suffocating the critters by adding dry ice (solid CO2) to the terrariums
It worked for a week, then the gnats came back with a vengence :(
- SPACING
The pic below shows an ensemble of terrariums, all different sizes and
shapes. The most important thing is fitting the right plants for the
amount of space available for a specific container. I normally have one feature plant, surrounded by filler plants and decorative items so as not to overcrowd the container. I have made the
mistake of filling a terrarium to the brim and killing the plants
because they barely have room to breathe or grow (See the small
terrarium on the top right? Yeah, that one. I'm lucky it's still alive.
Don't do that).
Terrariums of assorted sizes
An example below shows a large terrarium
(25cm wide x 30cm tall) with a hare's foot fern as the main feature and
about 3 different types of mosses as 'ground cover' with some decorative
shells covering the soil. Notice the amount of
space in this terrarium. The drainage and soil layers only make up about
20% of the terrarium to allow plenty of space for plant growth. I know that the hare's foot fern can grow to a significant size so I specifically chose a wide (and tall) container for it. This terrarium is about 3 months old and the
fern has almost doubled in size since planting. I will eventually have to cut off some 'feet' and fronds (rhizomes) for propagation when the terrarium gets too crowded cause the fern is too happy in there!
Large closed terrarium with hare's foot fern and assorted mosses
The smaller your container, the smarter you have to be about your use of space and plants selection. These containers below are consdiered medium sized (roughly 12cm width and height). Drainage pebbles used had to be smaller than the ones from the large container as I have less depth allocated here. Due to the lack of space, I also chose to use only mosses and lichen in these terrariums as they are slow growing and they do not have a deep root system. This means the soil layer can be thin and that the plants will have plenty of space to for good air circulation. Using a sheet of flyscreen instead of sphagnum moss for the filter layer also helps to save space.
Medium sized terrariums
Assorted mosses with the haircap moss (spiky moss in the middle) as a feature and pebbles for decor
One main moss (I believe it's called dicranum moss) with two others as filler, with preserved coral moss (white fluffy thingy at the top), stone arrowhead, ammonite fossil, and river pebbles for decor
- PLANT SELECTION
This is a tricky one. Old books on bottled gardens suggest using plants which do not flower, have smooth leaf surfaces, are slow growing, and prefer humid conditions. I have come across some stunning terrariums which violate these guidelines but I believe they are meant to be temporary rather than long-lasting.
An example of temporary ones would be succulent terrariums, which have grown in popularity thanks to their sculptural appearance and vast variation in colour. They are also almost impossible to kill, almost. Thing is, succulents hate wet feet (they love a good drink but the water needs to drain quickly), being stuck in a container is uncomfortable for them. They also love plenty of sunlight. Sticking them in a small enclosed glass container under strong sunlight is like putting them under a magnifying glass, killing them faster than you can say 'terrarium'. Exposing them to less light (therefore less heat) allows them to keep living BUT they start to stretch, looking for light, and lose their beautiful structure. There are however, a few species of succulents which have done well in lower light conditions (I was successful with several haworthia species in open terrariums). A general rule is to stick to those with dark green foliage (higher chlorophyll density, less reliance on sunlight intensity).
It is important to always choose plants which prefer the same conditions (same amount of sun, water, humidity etc). Otherwise one group will be happy and the others would be dying or worse case, when none of the plants are happy with the mid-way conditions you'll just get half-dead looking plants all the way through :(
Plants that I love to use include lichen and moss (absolute favourite!), ferns, air plants, and a small selection of succulents. I am looking forward to using club moss (a type of fern), venus traps and sundews, and baby's tears in my future projects.
An example of temporary ones would be succulent terrariums, which have grown in popularity thanks to their sculptural appearance and vast variation in colour. They are also almost impossible to kill, almost. Thing is, succulents hate wet feet (they love a good drink but the water needs to drain quickly), being stuck in a container is uncomfortable for them. They also love plenty of sunlight. Sticking them in a small enclosed glass container under strong sunlight is like putting them under a magnifying glass, killing them faster than you can say 'terrarium'. Exposing them to less light (therefore less heat) allows them to keep living BUT they start to stretch, looking for light, and lose their beautiful structure. There are however, a few species of succulents which have done well in lower light conditions (I was successful with several haworthia species in open terrariums). A general rule is to stick to those with dark green foliage (higher chlorophyll density, less reliance on sunlight intensity).
It is important to always choose plants which prefer the same conditions (same amount of sun, water, humidity etc). Otherwise one group will be happy and the others would be dying or worse case, when none of the plants are happy with the mid-way conditions you'll just get half-dead looking plants all the way through :(
Plants that I love to use include lichen and moss (absolute favourite!), ferns, air plants, and a small selection of succulents. I am looking forward to using club moss (a type of fern), venus traps and sundews, and baby's tears in my future projects.
Variety of moss and fairy's cup lichen in one terrarium
- WATERING
The amount of watering required varies depending on whether the terrarium is open or closed, its size, and the season. Open terrariums would of course, prefer more frequent watering compared to closed ones, likewse a larger terrarium would require more water than a smaller one. I prefer to underwater rather than overwater as mosses dry up but almost always come back to life after a bit of moisture. My routine is using a spray to water about once every two weeks in hot weather and about once a month or less in winter. Open terrariums would require double that amount of watering.
The way to gauge how much water the terrarium needs is by monitoring the condensation on the glass in the day and at night. Condensation in the day should be fine droplets which mostly clear by night. If large water droplets start to form in the day, then you have over-watered. I also check the water level in the drainage layer, the water should always sit below the soil layer! The consequences of over-watering? High humidity encourages rot, mold growth, attracts gnats (ugh!), and can give off a bad odour!
Good condensation level
If you have added too much water, have no fear! Leave the container open for a few days for evaporation to take place. If the process is taking too long, connect a piece of tissue to the soil layer and allow capillary action to take place (it acts like a siphon). The large surface area of the tissue allows evaporation to occur at a higher rate.
In case of accidental over-watering, apply capillary action
- POSITIONING
Letting your terrariums get enough light is important as you are growing plants in there after all! Sitting them indoors means they get very little light as it is so I like to sit them in a spot with lots of indirect sunlight. Most of my terrariums are sitting on a window sill facing South (we are in the Southern hemisphere) which means they don't get hit by direct sunlight. My two largest terrariums are sitting next to a window facing North which means they have access to direct light but I control how much light comes in through the blinds. The worst position for the terrariums would be getting lots of direct afternoon sun (West facing) as this heats up the terrariums and starts to cook the plants! So avoid this at all costs!
Terrarium array next to a South facing window
Mosses enjoying the abundance of indirect light
Airplants getting some air time
Terrariums getting sunlight from the North facing window
- GENERAL MAINTENANCE
As mentioned earlier, plants can sometimes outgrow their containers. With mosses, I would prune them back so the fringes are not touching the top or sides. Some moss colonies inevitably die so I would have to replace them with a healthier patch. It is also important to remove leaves that have fallen off or started to rot to prevent the spread of fungus.
The plants also love the occasional fresh air. For closed containers, I would open the top once in a while and blow in some air and move the leaves around. I do this more often in hot weather so the accumulated hot air gets replaced. It also gives me a chance to weasel out some gnats/insects that have snuck in. They tend to fly around when the leaves get disturbed (that's when I crush them and make sure they never set foot in my terrariums again). The same should be done for open terrariums to let the plants enjoy extra air circulation.
- ENJOY
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