If you've ever wanted to build your own indoor jungle but didn't know where to start, this guide is for you.

Making a terrarium looks complicated but with the right layers, plants, and position, you can create a low-maintenance, self-contained ecosystem that will be happy and healthy for many years, maybe even decades!

That’s why so many beginners choose closed DIY terrarium kits. Everything is designed to work together from the start.

Here's exactly how to make a terrarium, even if you've never touched one before.

What Is a Terrarium?

A terrarium is a miniature indoor garden built inside a glass container.

Closed terrariums (with a lid) create a humid, self-sustaining environment ideal for tropical plants. Once balanced, they require very little watering, often only every 6–8 weeks. I have one that I haven't watered in 5 years!

That's why they're perfect for beginners. They're also great if you go on holidays, you don't have to put it in the bathtub or get a plant minder in!

What You Need to Make a Terrarium

To build a healthy terrarium, you need specific layers. Each one serves a purpose.

You'll need:

• A glass container, preferably with a lid for a closed terrarium. There are lots of different lids to choose from. We use a selection of cork tops and balls, acrylic lids and glass lids.
• Drainage pebbles like scoria or clay leca balls
• Activated charcoal
• Terrarium soil mix (we make our own with organic potting mix, coco peat, worm castings and vermiculite)
• Live moss (optional)
• Small tropical plants (we use plugs because they are easy to put into position)
• Decorative elements like different colours of sand and gravel (optional)
• Basic planting tools
• Decorative figurines (optional) 

Many beginners get stuck sourcing these individually.

This is why a complete DIY terrarium kit makes the process easier. Everything is measured, selected, and designed to work together.

Step-by-Step: How to Build a Terrarium

Step 1: Add a Drainage Layer

Start with 1–2cm of pebbles at the base of your container.

This prevents excess water from sitting around plant roots.

Step 2: Add Activated Charcoal

A little bit of activated charcoal sprinkled on top keeps the environment fresh and reduces bacterial buildup. This step helps prevent odours and mould.

Step 3: Add Barrier Layer

We like to use a barrier layer next to prevent the terrarium soil falling straight into the drainage layer. Sphagnum moss or fibreglass mesh is perfect for this.

Step 4: Add Terrarium Soil

Add 3-5cm of soil, depending on your glass jar height. Closed terrariums need moisture retaining soil designed for tropical plants.

Slope the soil slightly if you want to create depth. You can have a lot of fun here creating different heights.

Step 5: Plant Your Terrarium

This is where your design begins! Arrange the plants before actually planting them into your terrarium.

Think about:

• Height variation
• Texture contrast
• Space for growth

Then gently plant and secure roots in the soil.

Take your time here. This is the creative part.

If you’re building something larger and more statement-worthy, something like the Green Oasis DIY Terrarium Kit is designed specifically for creating a full, enclosed ecosystem inside a spherical glass container.

Step 6: Add Moss and Decorative Details

Moss helps retain moisture and gives your terrarium that forest floor look, definitely our favourite look for terrariums!

Add stones or sand for contrast if desired. There are lots of different colours and shapes available.

Blue sand can be fun to add if you want to create a stream or pond. 

Step 7: Water Carefully

Closed terrariums need far less water than most people expect.

Lightly mist or add a small amount of water. You should not see water pooling at the bottom.

If heavy condensation builds up for several days, open the lid briefly to regulate.

Where to Place Your Terrarium

Place your terrarium in bright, indirect light.

The important thing is to avoid direct sunlight. Glass magnifies heat and can damage plants. I have definitely made that mistake in the past.

Think warm and filtered, not harsh and direct.

Common Beginner Mistakes

• Overwatering
• Using the wrong plants (succulents don't belong in closed terrariums)
• Skipping charcoal
• Sealing too soon without checking moisture balance

Most terrariums fail because of too much care, not too little.

Why a DIY Terrarium Kit Makes It Easier

The hardest part of learning how to make a terrarium isn't building it.

It's knowing what to buy.

A quality DIY terrarium kit includes:

• Proper drainage materials
• Activated charcoal
• Custom soil blend
• Terrarium-suitable plants
• Barrier Layer
• Tools
• Step-by-step instructions

Everything is designed to work together.

No guesswork or wrong plant choices and wasted materials.

If you're completely new and want something smaller to start with, our Medium Forest Jar is a simple entry point into closed ecosystems.

Final Thoughts On Terrariums For Beginners

Building a terrarium isn't just about plants, it's about creating something living with your hands, designing it the way you want and enjoying it grow. That's where the fun is!

If you're ready to build your own, explore our complete DIY terrarium kits designed for beginners and plant lovers. We have a terrarium to suit everyone. If you're not sure what one you would like, please reach out to us and we will guide you in the right direction. 

 

Terrarium Guide for Beginners: FAQs

How long do terrariums last?

A properly built closed terrarium can last for years, even decades! Because the environment recycles moisture internally, it becomes largely self-sustaining once balanced.

The key is using the right materials from the start and getting the plants settled into their new home.

How often should you water a terrarium?

Most closed terrariums need watering every 6-8 weeks.

There are signs when a terrarium has too much moisture. If the glass is constantly dripping with condensation, there’s too much moisture. The best thing to do is to take the lid off for a few hours so that some of the excess moisture can evaporate.

When in doubt, water less!

Do closed terrariums need sunlight?

Yes they do need light, but definitely not direct sunlight.

Bright, filtered light is ideal. Direct sun can overheat the container very quickly and kill the plants. 

Why is my terrarium foggy?

Light condensation is normal, it shows the water cycle is working.

Heavy fog that doesn’t clear means too much moisture. The best thing to do is to take the lid off for a few hours so that some of the excess moisture can evaporate. 

You can also put some string in to wick out excess water.

What plants are best for a closed terrarium?

Closed terrariums need tropical, humidity-loving plants like:

• Fittonias (we LOVE these!)

• Small ferns 

• Moss

• Peperomias

Succulents and cacti are not suitable for closed environments, they need dry conditions and are not fans of high humidity.

Are terrariums good for beginners?

We might be a bit biased but...yes they are! Especially closed terrariums.

Once established, they’re one of the most low maintenance indoor garden options available. They are a lot of fun to create and when they get established, they can throw out little mushrooms that are fun to watch for the few days they appear. Adding in springtails is also a lot of fun because you can watch them working away clearing all the plant debris in your terrarium. There's a lot of life in terrariums!

If you want to skip the sourcing stage and focus on building, you can shop closed terrarium kits here and start with everything included.