An aquarium terrarium can look stunning, but putting one together can be complicated. If you’re wondering how to make a terrarium in a fish tank, there are many components you’ll need to achieve that picture-perfect design.
Potting soil, gravel, live plants, rocks, sphagnum moss, driftwood, decorations, and a spray bottle are everything you need to create a terrarium in an aquarium.
If you’re interested in learning more about building an aquarium terrarium, our guide will help you understand all the steps involved and the best plants to use.
How To Make A Terrarium In A Fish Tank
Making a terrarium in a fish tank can take some work as there are a lot of steps to the process. It can also take some to get the design and layout right. However, with the correct method and supplies, it will make the job considerably easier.
We’ll be explaining how to build a terrarium in an aquarium step-by-step so you can create a slice of nature in your very own home. However, if you learn better visually, this video also does a great job describing the process:
Before you create an aquarium terrarium, there are some supplies that you’ll need.
- Indoor potting soil
- Activated charcoal
- Ornamental pebbles
- Clay pebbles or gravel
- Slate stones or rocks
- Decorative objects
- Plants like cacti and succulents
- Sphagnum moss
- Spray bottle
Once you have all the supplies you need, it’s time to start creating your fish tank terrarium.
First things first, you’ll need to choose a fish tank. Any size will do the trick, but you can get a lot more creative and house more plants with large aquariums. We recommend at least a 10-gallon fish tank as this will give you a decent amount of space to work with.
Depending on the type of vegetation you want to add, use an aquarium that comes with a lid or purchase a cover separately. Open terrariums will lose humidity more quickly than closed terrariums.
If your aquarium previously housed fish, make sure you give it a clean with some hot water and dish soap. You can also sanitize it with a 10% bleach solution, then rinse it thoroughly and allow it to dry.
Add a drainage layer (false bottom) to your setup. This will help increase humidity in the aquarium without waterlogging the soil. Gravel, clay balls, river pebbles, or glass beads work well for this purpose.
The drainage layer should be around 2.5 to 3 inches deep. It’s not necessary to drill a drainage hole into your aquarium if you add a false bottom.
Next, add a thin layer of activated charcoal pebbles. Activated charcoal is useful in closed terrariums as it will help keep the air fresh. It’s also beneficial in aquariums that house fish!
Apply 1 to 2 inches of sphagnum to the top of the activated carbon pebbles. This will help keep the potting soil and drainage layer separate.
Add a thick layer of potting soil (at least 4 inches deep). It doesn’t need to be flat, so get creative with different heights. You can build slopes, hills, and valleys to make your setup look more natural and interesting.
Now you’re ready to add plants to your fish tank terrarium! Decide which type of plants you’d like to add. Plants like pothos, baby’s tears, aluminum plants, African violets, Venus flytraps, and strawberry begonia are great choices for closed terrariums.
If you’re making an open terrarium, select foliage like cacti, succulents, peperomia, air plants, jade plants, bromeliads, and polka dot plants.
Make sure you don’t mix closed terrarium plants and open terrarium species together. They have different humidity and watering requirements.
Wet the soil slightly before you add the plants – this will make it easier to plant them. Once you’ve added your foliage, mist the environment with a spray bottle.
Add decorative objects like shells, driftwood, slate stones, rocks, branches, figurines, or terracotta pots.
Types Of Fish Tank Terrariums
There are a lot of different types of terrariums you can make from a fish tank, from simple indoor planters to extravagant underwater setups.
However, if it’s your first time making a terrarium, we’d suggest building a houseplant planter, desert terrarium, or tropical terrarium.
They’re straightforward to make and don’t require a huge amount of upkeep.
Houseplant planters are the easiest type of terrarium. All you need are some indoor potted plants and decorative objects like branches, figurines, rocks, and a pot.
A desert terrarium houses arid plants like cacti and succulent species, so you don’t need a cover or lid for this type of setup. The environment should be low in humidity, so water it sparingly.
Tropical terrariums are high in moisture so they can accommodate tropical plants. You’ll need to add a cover or lid to your enclosure and mist the environment frequently.
A paludarium combines both aquatic and terrestrial components. They can be pretty tricky to build and maintain.
A vivarium is an enclosure that houses live plants and small animals, typically reptiles, insects, or amphibians.
How To Maintain & Care For Your Fish Tank Terrarium
Although creating a fish tank terrarium is the fun part, you’ll also need to maintain and care for it to enable your plants to thrive.
Fortunately, looking after a terrarium is relatively simple and won’t take up too much of your time each week.
Below are all the supplies you need to maintain terrarium fish tanks.
- Aquarium scissors
- Long tweezers
- Water-soluble plant fertilizer
- Terrarium glass cleaner
- Microfiber cloth
- Activated carbon
- Spray bottle
Although terrariums are fairly self-sufficient when it comes to watering, you’ll still need to keep your plants hydrated every so often. The type of plant species in your fish tank terrarium will influence how often you need to water the container.
For arid plants in open terrariums, water weekly from March to October. Each plant should receive roughly a dessertspoon of water. During the winter, months reduce watering to every 6 weeks.
Allow the top of the soil to dry out completely between watering to prevent the roots from rotting.
Closed terrariums should be watered every couple of months or so. The high humidity in the container will make them almost self-watering.
Watch the condensation line. If it is higher than a third of the way up the container, remove the excess water with some kitchen paper.
On the flip side, if there is very little condensation, add around a tablespoon of water to increase the humidity in the container.
You’ll need to trim and prune your plants regularly to keep them healthy and promote new growth. Using aquarium scissors and long tweezers, snip off and remove any brown or rotting leaves.
Straggly stems should also be cut down to help develop bushier growth.
Make sure your setup has the right amount of light. A closed DIY terrarium should be positioned away from a window or in a location that receives bright, indirect sun.
An open terrarium will be best positioned on a windowsill or space that is in partial or direct sunlight. If your succulents start growing tall and leggy, that’s a sign that they need more light.
You should also make sure your terrarium is positioned away from radiators and other heat sources.
If you’ve added a layer of activated carbon to your terrarium, replace it around once a month as it will eventually become oversaturated.
DIY terrariums don’t need to be fertilized regularly, but they can still benefit from added nutrients to the soil every now and again. Use a water-soluble houseplant fertilizer around every 6 months.
Add about 1/4 of the recommended dose to wet soil. Don’t apply it directly to the plant roots as it will burn them!
Using a terrarium glass cleaner and a microfiber cloth, clean the outside and inside wall of the enclosure to remove dust, dirt, and water stains. It’s best not to use window glass cleaner, especially inside the terrarium, as it could kill your vegetation.
Best Plants For A Fish Tank Terrarium
There are many plants that are suitable for DIY aquarium terrariums, but it can be difficult to narrow down your selections. That’s why we’ve compiled a list of some of the best plants to use for a fish tank terrarium.
Tillandsia (Air Plant)
Tillandsias, commonly known as air plants, are an excellent choice for an open terrarium. As their name suggests, this species doesn’t take in nutrients from the soil – it absorbs them from the air!
This plant should not be planted into the soil, otherwise, it will rot. Instead, place the plant on top of the substrate. Tillandsias should be watered by being soaked in a bowl of water for 20 to 60 minutes every week. If in bloom, rinse them under water instead.
Tillandsias benefit from direct sunlight, so be sure to place them near a sunny window.
Bunny Ear Cactus
|Scientific Name:||Opuntia microdasys|
Any small cactus will work well in an open terrarium, but the bunny ear cactus is a particularly great option. The pads on this cactus look like bunny ears, hence the name!
The hairs on this cactus are quite prickly, so make sure you use gloves when handling it. Water whenever the first inch of the soil mix is dry.
Hens And Chicks
|Scientific Name:||Sempervivum tectorum|
Hens and chicks, also known as houseleeks, are succulents that feature an artichoke-shaped rosette. They reproduce rapidly and are very low maintenance, making them ideal for open terrariums.
This plant is very hardy and can thrive even in poor conditions. They are drought tolerant and should only be watered when the top layer of the soil is dry.
Mini African Violet
|Scientific Name:||Saintpaulia ionantha|
Mini African violets are one of the most vibrant houseplants you can add to a terrarium as they produce pretty flowers that come in an array of colors. Colors range from blue, violet, white, pink, red, and lavender.
The mini African violet can rot if kept in extremely high humidity, but they are best suited to an enclosed terrarium as they need moist soil. Bright, indirect light is ideal for this plant.
|Scientific Name:||Pellaea rotundifolia|
|Care Level:||Easy to moderate|
Miniature ferns are a terrarium’s best friend, so feel free to choose any fern species you like. However, button ferns are a particularly great example as they are compact and feature beautiful round leaves.
It grows fairly short and wide, so it’s ideal for larger terrariums that provide a lot of space. Provide them with bright, indirect sun.
|Scientific Name:||Leucobryum glaucum|
|Lifespan:||Up to 8 years|
No fish tank terrarium is complete without some type of mossy foliage, and pillow moss is a fantastic choice. It needs a lot of moisture and little light to thrive.
It’s ideal for a closed fish tank terrarium, particularly small containers as it grows very small. It’s also easy to sculpt, so you can create it into different shapes or even add it to pebbles, driftwood, and pots.
Fish Tank Terrarium Ideas: Plant Combinations To Try
If you’re struggling with how to lay out your aquarium terrarium and aren’t sure which plant combinations to try, here are a few ideas to get you started. You’ll have a unique and striking terrarium in no time!
- Mini African violets x 3
- Button fern x 2
- Moon valley x 3
- Mini succulents x 3
- Mini cacti x 3
- Strawberry begonia x 1
- Air plant x 2
- Spider plant x 1
- Polka dot plant x 1
- Golden clubmoss x 2
- Baby’s tears x 3
- Pillow moss x 5
- Earth star x 1
- Baby’s tears x 2
- Nerve plant x 1
Best Types Of Soil & Substrates To Use For A Fish Tank Terrarium
The best soil and substrate to use for a fish tank terrarium depends on the plant species in the enclosure.
Plants that need little moisture will benefit from sandy and well-draining soils, while species that need the opposite will need soil that locks in moisture such as those containing perlite.
Coco coir is made from coconut husks, making it very effective at retaining water. It’s ideal for plants that need ample moisture and root aeration to grow.
Coco coir normally comes in dry bricks or coarse chips that need to be rehydrated before use. As it is a refined material, it will take a substantial amount of time before it breaks down in your terrarium.
However, this type of substrate will need to be dosed with a fertilizer as it contains zero nutrients.
Sphagnum moss is one of the most commonly used substrates in terrariums, and for good reason. It excels at retaining water and has antimicrobial properties, which help protect your plants from bacteria and rot.
The only downside is its lack of nutrients, so you’ll need to add a layer of nutrient-rich soil or use a fertilizer.
Next up is perlite, which is a type of volcanic glass that is high in water. Due to its granular structure, it provides ample aeration to plant roots.
Perlite is useful when mixed in with soil as it helps keep plant roots moist without overwatering them.
Vermiculite works similarly to perlite, but instead of being a volcanic glass, it’s a mineral. It’s also better at retaining moisture, making it ideal for tropical vegetation that needs lots of it!
Potting soil is cheap and easy to find, making it a good option if you want to create a terrarium on a budget. However, it doesn’t work for all plants as it has a poor drainage system.
Arid species and those that need well-aerated and ample drainage won’t benefit from this type of substrate. That said, potting mix designed for cactus and succulent plants can be a decent choice for plants that need less moisture.
Sand, including aquarium sand and horticultural sand, is a great pick for a fish tank terrarium. It provides good drainage and aeration to your plant’s roots.
However, it doesn’t contain any nutrients, so you’ll need to mix it with a nutrient-rich substrate or add fertilizers.
Gravel or pebbles are a staple in terrarium fish tanks, both as a bottom layer and top layer. Gravel also provides plenty of drainage (better than sand!) and comes in an assortment of shapes, sizes, and colors.
Using activated charcoal in terrariums is helpful for absorbing contaminants like bad smells and purifying the air. Charcoal also retains a lot of moisture as it is highly porous.
You can use activated charcoal as a dedicated layer or combine it with other substrates. However, charcoal will need to be replaced every 2 to 4 weeks as it will eventually become saturated.
Clay pebbles are clay balls that have been treated with high heat in a kiln. They are commonly used as the bottom layer in terrariums as they increase aeration and drainage.
There are a lot of supplies and steps needed to create an aquarium terrarium, but we hope this guide helped you along the way. The possibilities are endless when it comes to terrariums, so have fun and unleash your inner creativity!
Remember to add a drainage layer to the enclosure, as well as charcoal, gravel, or any of the other substrates we’ve mentioned in this article. In addition, make sure you research the moisture, humidity, and light preferences of the foliage you want to add to your setup.
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