Fern Terrarium: Good Plants for your Terrarium
Terrariums don’t just add a stunning decorative flourish to your home - they are perfect micro-environments for humid-loving plants. This article shows how to create your own woodland habitat glass terrarium.
Plant terrariums were invented by British medic National Ward in 1829. His ‘Wardian case’, effectively a miniature greenhouse, took off as a way of shipping plants back from the British colonies. In the 1840s, it became a must-have for the urban middle classes during the ‘Victorian fern craze’. The sight of luscious fronds under glass must have been a welcome sight in the polluted metropolises of early industrial England.
Although modern terrariums are marketed as nifty displays for succulents and cacti, such desert species can be prone to rot in moisture-trapping environments. Here, we restore the terrarium to its former glory: a way to grow delicate, humid-loving plants in homes where the air would otherwise be too dry.
Choose either a lidded or open glass container, depending on how humid you want your terrarium to be.
For ultra-humidity, use a bell-jar cloche – it will trap moisture completely and add a touch of faded romance to your décor. Closed terrariums like this will recycle its own moisture and the plants will produce their own oxygen.
If you go for open glass containers, select ones with curved edges: think round fish bowls or vessels with fluted necks. With these, you will need to mist your plants several times a week or more.
If the neck of your terrarium is too narrow to fit your hand through, use bamboo sticks as ‘chopsticks’ to insert and arrange your plants.
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Plants for the Terrarium
All the plants below will thrive under glass in bright, indirect sunlight with temperatures of between 40-65F or 5-18C. Always keep your terraria out of direct sunlight.
Pair your plants carefully as some have slightly different watering requirements!
Variegated spider fern - Arachnoides simplicior 'Variegata’
This fern will tolerate wet soil and heavy shade. Water sparingly in winter. Good for either closed or open terrariums. Learn more about ferns.
Native to New Zealand and loves moist soil. Good for either closed or open terrariums.
Nerve plant - Fittonia
This is a tropical plant native to Peru. There are many colourful varieties. It likes similar conditions to woodland ferns from temperate climates. These plants require extremely high humidity (up to 90%) so these will thrive in closed containers alongside maidenhair ferns and Boston ferns. Nerve Plants are also popular in vivarium with aquatic and semi-aquatic animals!
Ivies should be grown in open terrariums only as they are not tolerant of constantly wet soil.
Boston fern - Nephrolepis exaltata 'Marisa'
The Boston fern was fashionable during the Victorian fern craze. Perfect with other humid-loving and thirsty plants like the fittonia and maidenhair fern in closed terraria.
Strawberry Begonia - Saxifraga stolonifera
Originally from east Asia. Make sure the soil is constantly moist. Pair with ferns in either closed or open terraria.
This is a climbing plant that is easy to train around wood. Loves warm, humid air and moist soils. Good for open or closed terrariums.
Dwarf maidenhair fern - Adiantum microphyllum
These grow best in closed terraria. They require lots of humidity and watering – an ideal companion for the fittonia and Boston fern. Make sure the soil has lot’s of water-retaining sphagnum moss.
Native to South America, this plant loves the same moist soil mixes that the ferns prefer. It doesn’t like water on its leaves so it’s best to keep in a closed terrarium that you don’t have to mist-spray.
Button fern - Pellaea rotundifolia
Native to New Zealand. This plant requires very high humidity so closed terrariums are best. However, it does not like being over-watered so don’t place it with maidenhair ferns or fittonias.
Getting the soil mix right will be an important part of mimicking a woodland habitat. You need soil that will retain moisture and is rich in organic matter. Your soil should never get water-logged.
Perfecting your Terrarium Substrate
Because a glass terrarium lacks drainage holes, it will need a bottom layer of sand or gravel to collect excess water.
Place a 1 – 2 inch layer of horticultural sand or gravel at the bottom of your container. Next, add a 1 – 2 inch layer of horticultural charcoal (alternatively, mix the charcoal with the sand or gravel).
Now comes the dirt. This is where your plants will spread their roots.
Your woodland terrarium plants require a soil high in organic matter. Although many guides list peat as an essential part of organic soil mixes, peat harvesting is extremely environmentally destructive. Instead, we recommend coir – a byproduct of coconut.
Thoroughly mix equal parts coir, coarse sand (or perlite), and organic compost (sometimes called ‘humus’). If you can, add one-part leaf mold or sphagnum moss – your ferns will love this.
Place a layer of the soil mix into your terrarium, on top of the gravel and charcoal layer.
The amount of soil you need will depend on how big your plants are. Place a layer of soil around one inch deeper than your plant roots.
Dig holes in the soil enough to take the root balls of your plants.
Insert your plants and pat the soil around them to secure. If your terrarium has a narrow neck and you cannot reach inside, pack the soil with a small, flat object tied to a long stick.
- Mist your plants thoroughly and water in.
No woodland habitat would be complete without moss – a primitive plant type called ‘bryophytes’. In the wild, they absorb rainfall and help maintain a humid atmosphere. Not only will they add a serene layer of greenery to your woodland world, they will keep other terrarium plants happy.
Place the moss directly on the soil between your plants. Press them gently into the soil to encourage them to attach.
Moss also attach to other substrates like coarse rock, antlers, or logs. These substrates are an excellent way to decorate your terrarium. Tie the moss loosely to these substrates for a couple of weeks, removing the ties once they’re securely attached.
Bottle-spray the moss very often, particularly in the first few weeks of introducing them into your terrarium.
Here are some species that will do well in your woodland terrarium:
Feather moss - Ptilium crista-castrensis
Regular misting required
Cushion moss - Leucobryum glaucum
Regular misting required
Star moss - Tortula ruralis
Fern moss - Thuidium delicatulum
Regular misting required
Golden Clubmoss - Selaginella kraussiana 'Aurea'
Very regular misting required
A closed terrarium will rarely require re-watering. Watering requirements for your open terrarium will depend on the plant species you have chosen. Generally, plants need less water in the winter.
Ideally, you will use rainwater to water your plants as tap-water often contains harmful minerals that accumulate in the soil and damage plants over time. Leave a few containers outside to catch the rain. Your plants will love you for the extra effort.