Honestly, ferns really are a terrarium lovers best friend.
They’re almost universally suited to terrarium life. They like nothing more than a warm environment with lots of humidity and plenty to drink (much like me really).
Maybe more than any other type of plant, there’s a huge variety of shapes and textures.
For me, it’s rare that a terrarium feels complete without at least one fern.
In this article, we’re going to show you where to find the best ferns for your terrarium, and how to keep them healthy and happy.
Let’s jump in.
Growing Ferns in Terrariums
Ferns are a versatile and often hardy plant species.
They’re found naturally growing terrestrially in moist earth, and epiphytically on the trunks of trees and in the crevices of rocks.
Characterised by their unique fronds (divided leaves). They range from broad, rounded and flat to fluffy, ruffled and frilly.
Whatever “look” you’re going for in your terrarium, there’s a fern with the size, colour and texture to fit.
The Ideal Fern Growth Environment (Hint: It’s a Terrarium)
As houseplants, ferns can be somewhat demanding.
They love moisture – both around their roots and in the air around them – so dry air and cold drafts can really take their toll. Making it difficult to manage ferns in open spaces throughout the different seasons.
Not a problem for terrariums though!
A closed terrarium environment traps moisture, warmth and generates its own humidity. So terrarium ferns have ample supply of everything they need.
Plus, on a whole, ferns are shade-loving plants.
They typically grow on forest floors and under tree canopies, so they’re used to bright, indirect sunlight.
They’ll pair nicely with the majority of other suitable terrarium plants.
Planting Terrarium Ferns Properly
Ferns have a range of different root structures, some of which need some special attention when planting/attaching.
Many still have a typical root ball, these can be planted as you would any other plant. Though fern roots are typically short and delicate. So it’s important to have a nutrient rich substrate that can retain moisture well, so the shallow roots can find it.
Epiphytic ferns (and many terrestrial) tend to grow from a creeping rhizome rather than a central root structure. A rhizome is essentially a horizontal stem which sprouts more fronds as the plant grows and expands.
These kinds of epiphytic ferns often don’t have much in the way of roots. They instead attach themselves and absorb water via small hair-like structures on the rhizome called rhizoids.
Easily confused, I know…
So when planting/attaching epiphytic ferns, make sure they’re on a damp surface or misted regularly. It can help to saturate some sphagnum moss in water and use that as a base to attach the fern too, instead of a dry branch surface.
The Best Ferns for Terrariums
The best terrarium ferns are generally from the tropics.
Fern species that enjoy the high temperature and humidity that a terrarium provides.
Ideally we’d want ferns that don’t grow too big, or can at least be easily trimmed (e.g. Pteris cretica ‘Albolineata’).
Thankfully for us, ferns grow in all shapes and sizes – which gives us lots of options for our terrarium design.
Small Ferns for Terrariums
Sometimes we can make use of smaller cultivars of our favourite houseplant ferns, whereas others will require something a little more specific.
Or you could always propagate your own ideal fern…
So many potential little ferns, so little time!
Miniature Ferns (Dwarf Ferns)
Many of the more popular houseplant ferns have dwarf varieties that are a more appropriate size for terrariums.
The likes of:
- Adiantum microphyllum (Dwarf Maidenhair Fern)
- Nephrolepis cordifolia ‘Duffii’ (Lemon Button Fern)
- Nephrolepis exaltata ‘Fluffy Ruffles’ (Dwarf Boston Fern)
These all typically grow about 12 inches tall, making them great for large and medium sized terrariums.
Much likes these particular species, dwarf fern varieties tend to have a much smaller maximum height, but can still grow wide and bushy.
So if you’re looking for a truly compact fern, you’ll want to take a look at the micro ferns.
Micro ferns are fundamentally tiny.
As in, won’t grow larger than a couple of inches kind of tiny.
If you’re building a super small terrarium or just want to add some delicate texture to your ground cover, these ferns could be a good choice for you.
- Bolbitis heteroclita ‘Difformis (Mini Asian Water Fern)
- Lemmaphyllum microphyllum (Japanese Beard Fern)
- Microgramma heterophylla
- Crepidomanes minutum
Micro ferns tend to be epiphytic, as such small, delicate plants often struggle to compete for resources on the forest floor (and would be easily trampled).
One such genus of micro ferns is the Hymenophyllaceae genus. Commonly called “Filmy Ferns” because they’re just a single cell thick!
Understandably they’re very prone to drying out but you can grow them in a terrarium if you keep the humility and moisture sky high.
How to Propagate Ferns For Your Terrarium
Ferns are ancient, non-flowering, spore producing plants with some unique parts and structures.
Which means we can’t get them from seeds, but it does offer up new ways and opportunities to get new plants from them.
Spores are the natural way that ferns typically reproduce.
They’re very effective in the wild with open air, breezes and transient wildlife. Not so effective in a sealed terrarium with no airflow.
That being said, it is possible to harvest spores from mature ferns and use them to create new plants, but it’s quite a difficult process to manage.
Here’s a guide if you’re feeling up to the task.
The easiest way to propagate ferns tends to be through division.
Essentially just dividing a single larger fern into smaller viable plants. By creating sections with a good amount of fronds and roots/rhizome stretch, you can give them a fighting chance.
Depending on the type of fern, dividing the plant can be done through several ways.
Splitting Larger Ferns
The larger and bushier ferns tend to have root balls, or at least something resembling a proper root structure.
These can often be gently teased apart to form 2 or 3 smaller plants, each with their own set of fronds, stems and roots.
Splitting Creeping Rhizomes
For epiphytic ferns that grow along a creeping rhizome, you can split the rhizome itself to form viable individual cuttings.
Over to You
What ferns do you use in your terrariums? Let us know in the comments.
I’m particularly interested in hearing about exotic micro ferns.