How to make a terrarium: experts explain how to master these miniature gardens

Once you find out how to make a terrarium you won't believe it's taken you this long to try it out. You'll soon become hooked on the terrarium trend and you won't be able to resist adding to your collection. 

I have a few terrariums in my own home, and from experience I know it only takes an hour or so to create your first one. What's more, you don't need many materials either. Mason jars, goldfish bowls, candy jars and even French presses can all be used to make beautiful containers for DIY terrariums. You can also pick up mini plants cheaply, so it's an inexpensive gardening habit to acquire. 

I've found that creating a terrarium is one of the most rewarding and easy-to-maintain indoor garden projects you can try. These small, self-contained displays are perfect for adding a design element to your interior. 

How to make a terrarium in 5 easy steps

I've found that terrarium plants will grow well in most containers as long as your terrarium is properly set up and maintained. 

'A terrarium provides a controlled environment for plants, with adequate moisture, light, and air circulation,' explains houseplant expert James Kinsella from outplanted.com. 

Follow these simple steps for making a terrarium and show off some of your favorite mini indoor plants. 

You will need:

• A glass or plastic container
• A layer of gravel or pebbles
• Potting soil suitable for a terrarium, available from Amazon
• Activated charcoal
• A selection of mini plants suitable for a terrarium
• Spoon for placing soil
• Long tweezers for adding materials to the container
• Moss and other decorations

1. Choose the right container  

This is one of the most important things to get right when learning how to make a terrarium for the first time. The good news is there's lots of flexibility when choosing a container for your indoor planter. You could opt for a large glass jar, a hurricane vase like this one from Amazon, fish bowl, or other clear container with a lid or opening. Some plants thrive in a closed terrarium while others prefer an open one.

If you're planting succulents choose a glass bowl with a slanted open design like this stylish one from Amazon to create the right environment for them to thrive as they don't like being enclosed.

Make sure the container is large enough to accommodate the plants you have in mind. It should also be thoroughly clean and dry before you start, and there should be plenty of room for your plants to grow.

Plastic containers, like this acrylic one from Amazon, work just fine too. They are lighter and have a good transparency rating, and some even have an automatic misting function for those all-important humidity levels.

2. Add a layer of gravel or pebbles to the base

Add a layer of gravel or pebbles, such as these polished river rocks (available from Amazon), to the bottom of the container. This will help with drainage and prevent the roots of the plants from sitting in water, which will be detrimental to their health.

'Your terrarium's base layer of tiny rocks will serve as the drainage system,' explains Aaditya Bhatta, founder of Plantscraze. 'Add a layer of pebbles or small stones 1-2 inches deep to the bottom of your terrarium.'

On top of the gravel or pebbles, it's a good idea to add a skinny layer of activated charcoal (also from Amazon). This will help to filter the air and prevent mold and bacteria from growing in the terrarium.

3. Layer up the right potting soil

Make sure you use a soil that is right for terrariums, as regular garden potting soil can contains fertilizers that your mini plants don't need.

'Cococoir, peat moss or houseplant soil works with most terrarium plants, aside from succulents which prefer a well-drained inorganic medium,' according to the team at Ambius, who specialize in enhancing interior landscapes. 'Some people choose to make their own soil but if you’re short on time, garden store houseplant soil works just fine. For succulents, you’ll need soil with a sand or gravel mixture.'

You should add enough potting soil to make it deep enough for the roots of your plants, says Aaditya Bhatta. 'I advise using a layer of around 2-3 inches thick.' 

4. Choose and arrange your plants

When making a terrarium, Zeeshan Haider, CEO and founder of GreenryEnthusiast.com, says the process starts with selecting the right plants. 'Certain plants do better than others in a terrarium, so it’s important to consider their light, water, and soil needs when making your selection. The key is to pick plants that don’t require too much water, since too much moisture can lead to mold and other issues.'

Choose plants that are suitable for terrariums, such as ferns, mosses, and small indoor succulents. Get creative and mix up the plants, colors and sizes, just as you would with your outdoor container gardening ideas. 'Plant the most significant plant you have first,' suggests Aaditya Bhatta. 'Moving through your terrarium from the back to the front is the simplest way. The design of your terrarium is entirely random. Experiment with the setup and have fun!'

Make a hole in the soil big enough for the roots of each plant. 'Tools like pencils, chopsticks, and long spoons are ideal for this task,' says James Jennings of HomeGardenHQ. Remove the plant from its container and carefully loosen the soil around the roots. Plant in the soil, leaving enough space in between plants for growth. Try using a cork on the end of a skewer or chopstick to tamp down the soil.

Once your plants are all positioned and you're happy with the layout add a second layer of soil. 'Make sure you pack the soil around the plants so that they are securely planted,' says Lindsey Hyland, founder of Urban Organic Yield. 'Finally, add 1 or 2 more inches of gravel or small stones to the top for decoration if you like.'

5. Add the finishing touches

Once your plants are in place, it's time to add decorations to your terrarium, such as rocks, shells, and other mini figurines of your choice. You can even turn it into a Christmas terrarium by adding a few festive decorations to the mix. Just make sure not to overcrowd the terrarium and leave enough space for your plants to grow.

You can also add a layer of live moss, which will look great especially when paired with sand and rocks. It's easy to maintain and lasts for quite a while without needing to be replaced. Or try decorative preserved moss (try Amazon), which comes in a range of colors to suit your decor. 

Use a mister or small watering can with a rose attachment to water the plants so they are just damp. Finally, close the terrarium with a lid (if you've chosen a closed one) and your mini plant ecosystem is complete. 

How to make a mason jar terrarium

Making a terrarium in a mason jar is super easy to do. The area for planting will be small though so factor this in when choosing a plant and any ornaments. 

The outlay for a mason jar terrarium is minimal. All you need is a jar, soil, plants and moss. Plus decorations of your choice. You can stand the mason jar upright or invert it and plant into the lid. Alternatively you can lay it on its side, as pictured above. 

Our step by step explains how to plant a mason jar terrarium in the lid, but the method is the same whichever way you choose. Planting the lid can be an easier alternative to reaching down inside the jar for planting and aftercare.

1. Make sure both the mason jar and accompanying lid are clean, rinsed properly and thoroughly dry. 
2. Carefully remove your chosen plant from the pot by squeezing the sides to release it.
3. Position the plant in the lid of the jar. Cover the rootball with soil and pack soil around it to secure the plant.
4. Add a layer of moss, pressing it into place around the base of the plant.
5. Decorate with stones, shells, mini figurines and other small garden decor ornaments of your choice.
6. Invert the jar over the plant, being careful not to damage any leaves by using your fingers to coerce any stray greenery into line. Then carefully twist the lid shut.
7. Position your terrarium in bright indirect light. Check every few weeks to make sure the soil is moist. If you see lots of condensation in the jar, leave it open for a few hours to let some air circulate and clear the mist.