Crested Geckos – How to create a Bioactive Terrarium

How To Create A Bioactive Habitat For Your Crested Gecko 

The dictionary definition of bioactive is: ‘(of a substance) having or producing an effect on living tissue’.

What we take it to mean is to create a system that resembles the living ecosystems that the ancestors of our pets first came from, and that their wild relatives still inhabit. It’s a way of using the entire environment to provide a home for our pets that’s as close to nature as possible, and one that takes care of itself to a greater or lesser degree.

Terrarium

For this crested gecko project, you will need a glass terrarium with more height than floor area. We recommend using a terrarium measuring 45 x 45 x 60cm (18 x 18 x 24”), a tall terrarium which suits their arboreal (tree climbing) lifestyle. Taller and wider terrariums are available, and more space is always beneficial.

Background

For a background, you can either use the provided polystyrene one (which plants will grow up, but feeder insects can burrow into) or go with cork, picture backgrounds for the outside, or make your own with expanding foam and sealant. Once you have decided on what background to use, make sure that it is firmly fixed in place and sealed (if necessary) before moving on to the next step.

Lighting

Getting the lighting right is vital. The geckos themselves require low levels of UVB, which can be provided either with a compact bulb or a small T5 or T8 tube. Several systems are available, so there should be one to suit everyone’s pocket! Without extra light, your plants are not going to survive. Plants require the correct wavelengths of light in order to thrive, and dedicated plant light systems are a must; again, several different types are available. For the 45 x 45 x 60cm terrarium, one light bar that contains a UV tube and an LED plant light tube will be sufficient; a taller or wider terrarium, however, will benefit from a plant – specific spotlight that will be strong enough to punch a bright beam all the way to the bottom of the terrarium. We can, of course, guide you to the particular light configuration that will suit your particular setup.

Substrate

The most important part of the living system is the substrate – your forest floor. This is the powerhouse that will turn waste into plant food, keep your plants and animals healthy, and regulate humidity.

We don’t want our plants to be sitting with their feet in water (this can cause rotting), but ideally we want a small reservoir under the substrate to keep it moist. To achieve this, we use a drainage layer, in the same way that when you put plants in a pot you include bits of broken plant pot to help the soil drain.

This drainage layer can be gravel, any other granular substance that doesn’t rot, or expanded ceramic balls. These are lightweight and provide a huge surface area for bacteria to colonise, which will help to detoxify liquid waste that trickles down to the bottom. These ‘good’ bacteria turn harmful compounds into harmless ones that plants can use as food, in exactly the same way that the filter on a fishtank does.

Layer your drainage material fairly generously, then lay a barrier on the top of it to prevent substrate working its way down between the grains and clogging the whole system. Terrarium fleece or  mesh allows liquid through freely, but is fine enough to prevent substrate getting through.

Once your drainage layer is installed and sealed, then it’s time to add substrate. 

You want to replicate the tropical forest floor, so you need a good base. If you don’t want to mix your own, there are some excellent pre mixed substrates out there these days; they are probably the best way to start if you haven’t gone bioactive before. The ideal substrate holds water but is free draining, has a variety of grain sizes to prevent compaction, and is slow to break down.

This can be achieved by mixing coir fibre, orchid bark, cork bark litter and moss in varying quantities – or you can just buy a bag of ready mixed!

On top of this, if you can, should go a generous layer of leaf litter. You can buy dried leaves, or collect your own; oak, beech, magnolia, sweet chestnut, horse chestnut, mulberry, hawthorn, birch, poplar and sycamore are all commonly used. If you collect your own, take them from the ground after they have fallen – the tree has removed everything it needs from them, making them safe to use. Make sure you are away from roads, and any areas where unwormed dogs and cats might have used them for a toilet!

As these leaves rot down they will add important substances and micronutrients to the soil that both your plants and your clean up crew will very much appreciate. If you are collecting from the wild, you will also be adding beneficial bacteria from the forest floor that will help the natural action of your substrate.

Clean up crew

Now it’s time for the next step – introducing the clean up crew.

Your clean up crew do all the heavy lifting in the bioactive system! They break down solid waste into a form that allows the beneficial bacteria to get to work on it, reduce your piles of leaves to the lovely rich humus that your plants will appreciate, and are an interesting spectacle in their own right.

Springtails, woodlice – tropical and native – earthworms, small millipedes, and even mealworms are all used.

Springtails are tiny, pale coloured arthropods that live in and feed on decaying matter. They are instrumental in keeping your substrate in good order; if you turn over a clump of decaying leaves in the woods, they’re the tiny creatures that bounce away from the light. They will break down waste matter, and help to stop moulds and fungi from taking over the substrate.

They can be bought as cultures ready to add, and you can also buy extra food for them to help build their numbers up when they are first introduced.

Earthworms keep the substrate turned over and aerated, as well as taking their own share of leaves and other waste matter.

Woodlice, again, eat decaying matter (especially wood and leaves), and should your vivarium inhabitant eat them they won’t be harmed – in fact, as the shell contains a high level of calcium, it can be very beneficial!

If you have collected your leaf litter from the wild, you may well find that you have introduced other small invertebrates to the system – tiny snails, millipedes, and soil mites. These will all take their place in the soil community you have created, and really contribute to the effectiveness of your living substrate.

Once you have added all your clean up crew, you’re ready to start planting and adding branches.

Branches

These geckos need to climb, so we want to create an environment where they can self regulate their exposure to heat, UV light, and humidity both vertically and horizontally. At least one branch should stretch almost the full height of the habitat, and reach from one side to the other. Then the other spaces can be occupied by smaller branches, giving the gecko a choice of climbing and resting areas.

Obtaining good quality branches can be difficult. They can be collected from outside, but be aware that you need the permission of the landowner before you can take any materials away. If you know anyone pruning a fruit tree then that is a great source of wood, or if you spot a tree surgeon at work they may be fine with you taking a few bits. But always get permission first!

Also, don’t worry about scrubbing or bleaching wild-collected wood. Any microorganisms present on the branch will tend to be at worst harmless, and are more likely to be beneficial to your fledgeling bio-active habitat. The only exception to this are branches from ponds where native amphibians are present, or anything picked up from the side of a road. Best to avoid these if possible.

If you can’t get hold of native, wild collected specimens, fear not. We can supply a good choice of cork branches, grape vines,  liana vines and bark pieces that are eminently suitable for your habitat. 

Plants

This guide will be covering the plant species that are easiest to acclimatise and use in a wetter type of environment. All of the following plants have been used by us with success in setups of various size, so with suitable lighting you should be able to achieve a jungle effect in no time!

Remember that if plants are purchased from a garden centre they should be washed under running water to remove pesticide and herbicide residues, and also have the soil removed from around the roots and the roots themselves gently rinsed with clean running water. They can be used in the terrarium straight away, but in this case no animals should be introduced for around six weeks.

We use the term ‘epiphyte’ to describe some of the following plants, or say that a plant can be grown ‘epiphytically’. An epiphyte is a plant that grows on another plant but is not a parasite; for instance, a fern growing on a branch is an epiphyte, but mistletoe is a parasite. Many mosses and ferns, most bromeliads and a large number of orchids are epiphytes, and any plant that has aerial roots can often be grown in such a fashion.

It’s worth planning out your terrarium before you add your plants; you will need upright, climbing, cover and floor plants. Have a think about leaf shapes and how quickly these plants will grow.

Pothos (Epipremnum sp.)

A plant with many common names, you will see this plant listed as Pothos, Devil’s Ivy, Epipremnum or Scindapsis. There are several different individual species often offered for sale, but all will do very well in a bioactive setting. They are a perennial tropical climber that relies heavily on aerial roots which will attach firmly to most surfaces, and are a recommended houseplant for air purification. They are available in several different leaf colours including variegated and golden, and mature plants produce large, oval shaped leaves that are sturdy enough for all but the largest reptiles to stand on. 

This plant is very easy to propagate from cuttings, and grows very well in the vivarium. It can either be planted in the base substrate and allowed to twine up the decor, or can be grown as an epiphyte with the roots tucked into a pocket of moss and soil in a hollow section of log. Don’t be afraid to cut it back – hard, if necessary – because this plant can grow very large and take over the vivarium. Pop the cuttings into a container of water, and they will root without any further intervention. 

Spathiphyllum (Spathiphyllum sp)

Also known as Peace Lily, this is another tall plant that can make a very showy display. Tall, spear shaped glossy green leaves can get up to 60cm long, so ideal for making a vertical statement! This plant seems able to survive both with its toes in water and more on the drier side, although it should never be allowed to dry out. It will happily flower in a terrarium, provided it has enough light and isn’t waterlogged.

Spider Plant (Chlorophytum comosum)

Even non gardeners can recognise this plant with its arching sprays of variegated leaves and long trails of miniature versions of itself. It is available in a plain green, and some very closely related plants are brightly patterned with yellow and pale green. Native to tropical and southern Africa, it’s a popular houseplant worldwide and is very happy in a vivarium situation. 

It can either be grown as an epiphyte in a planting pocket or in a soil filled cavity of a log, or in the substrate itself although it doesn’t like to be sitting in permanently wet soil. It develops white, fleshy roots that can store a certain amount of water, which is at least partly why it does so well in a hanging basket – it can even be grown outdoors in the UK in the summer.

Spider plants like bright light but don’t need to be in the brightest spot; dappled sunlight around the edges of the enclosure work just fine.

Tradescantia (Tradescantia sp) 

You have probably encountered this plant at some point under one of its many common names: inch plant, wandering jew, spiderwort, moses-in-the-basket, purple heart, or Indian paint. Like most of our terrarium and house plants, this one is a range of species rather than just one although care requirements are very similar across the whole group.

With fleshy stems that easily root whenever they touch a suitable surface this plant spreads easily and makes a good trailing vine rather than a climber. It likes medium to bright light, although the more red and purple pigments in the leaves the more light it likes, and in common with most plants with this sort of stem it will rot at the base if kept with its feet in the water.

It’s a native of the new world between southern Canada and northern Argentina, so as well as the tropical forms that are suitable for the terrarium there are species that will grow in your garden!

If you’re lucky, it will even flower in the terrarium. 

Philodendron (Philodendron scandens) 

Another tropical climber, this plant is a little more delicate than the cast iron Pothos but its large, glossy dark green heart shaped leaves make an impressive display in the larger terrarium. There are species that do not climb, and these can work very well in a terrestrial setting, or even a woodland or semi-arid. The classic Philodendron provides good cover for shy species, and is robust enough for larger species to climb on as well.

Ficus benjamina 

More commonly known as weeping fig, in its natural habitat it’s a tree that can reach thirty metres tall! It’s a plant that can be a little difficult when grown as a houseplant, as dry air will cause it to drop its leaves. When kept in the humidity of a tropical terrarium it thrives, and if carefully trained can develop stems robust enough for larger geckos and chameleons to walk on.

Doesn’t like to be sitting in water, so an effective drainage layer is a must for this plant. It’s architectural and handsome, and is very suitable to make a striking centrepiece for your terrarium.

Ficus pumila

A climbing fig that, if grown outside in tropical regions, can become incredibly invasive and even smother other trees and plants, as well as damaging any man made structures it scrambles over. The properties that make it invasive make it an ideal inhabitant of our bioactive setups, as it will tolerate humid or quite dry atmospheres, and is happy to grow in lightly damp or very soggy ground. It climbs with aerial roots that attach to anything, including glass.

We have found that when this plant is used, it seems to take a long time to establish. It sits and appears to do nothing, until you look in the terrarium one morning and it’s half way up the wall! Probably the best plant for covering multiple surfaces, but will sometimes need to be cut back hard. Each piece with an attached root can be used to propagate new specimens, but after you’ve got one of these established in your tank you won’t need to buy another one…ever. If grown in screen top enclosures it will squeeze out between the wires in an attempt to reach the light. 

Is available as an attractive variegated form, but this must be kept under very bright light to keep the white portions of the leaves from turning green. If grown in darker conditions it goes all green, and needs exposure to bright light to restore the leaf markings.

Along with pothos, this is one of the failsafe terrarium plants. 

Umbrella plant (Schefflera arboricola) 

Another one that will grow into a small tree if grown outside in tropical regions, this plant is sturdy and can either grow tall or be kept compact by pinching out the growing tips. It does use aerial roots to attach itself to decor – cork bark allows it to grip incredibly well – and if it looks to be getting too leggy, then cut the top off and stick it in a vase of water. Within a few weeks new root growth will have occurred, and the rooted crown can be planted back into the terrarium.

Variegated versions like brighter light and slightly higher temperatures than the all green version, and both will not tolerate having their roots permanently wet. Keeping humidity up will also deter the more common pests that are found on this species when it’s used as a houseplant – red spider mite and scale insect.

This is one of those plants that if it likes your setup will be tough and beautiful for years, but can be awkward if conditions are not to its liking.

Asparagus fern (Asparagus setaceus) 

Not really a fern, but part of the lily family! This delicate looking plant is actually quite tough, and is a real survivor even if it’s not happy with conditions. The delicate sprays of foliage that spread out from the wiry stems hide small thorns, which is how it grips decor to climb. They are sharp, but as they are pointing backwards in order to aid climbing they aren’t a risk to most terrarium inhabitants. Be careful when putting your hand through a bunch of that light, ferny foliage!

We’ve grown this in planting pockets and above a water feature in a riparium and so far, it’s done very well. Too much bright light will cause the leaves to brown and scorch, and too little will cause them to go yellow. High humidity is much appreciated, and it’s an excellent plant for providing light shade and cover for nervous lizards.

If it’s really happy with its home it can flower and even produce small berries, which start out red and blacken with age. These should be removed from the plant as they are toxic.

Bromeliads 

No species name given as this is a large group of impressive foliage plants that are often sold for use in terraria, even though they can disappoint with short survival times.

The bromeliads – like airplants – have large, showy leaves (called bracts) surrounding their tiny flowers, and it’s for these brightly coloured bracts that most people will buy a bromeliad. Unfortunately, if you plant the bromeliad in the soil it will likely just rot from the base in a very short space of time.

Most bromeliads are epiphytes, and grow best when allowed to attach to a branch or be placed in a planting pocket on the walls of the terrarium. Wrap the roots of the bromeliad in moss and soil, then bind them in a crevice of a branch or against a knot hole in a piece of cork, and allow them to attach naturally. They hold water in the central ‘vase’ formed by their thick, waterproof leaves, and this is the only watering many bromeliads need.

When mounted like this, most bromeliads will keep their bright colours for longer than those just tucked in to substrate. Once the flowers are finished, the plant then pushes out miniature versions of itself called ‘pups’ as a way of propagating itself. These pups can either be removed to be planted elsewhere, or can be left to form a very natural looking clump within the terrarium.

Common bromeliads that do best when grown epiphytically include Vrisea, Guzmania, Neoregelia, Nidularium and Tillandsia.

Cryptanthus – earth stars – are the exception to this rule, and produce an impressive spread of foliage that flushes pink in bright light when planted in well drained soil.

We hope this guide will help you to develop your crested gecko’s habitat – remember to take lots of photos, and let us know how you get on!