How To Make An Open Terrarium: Your Ultimate Guide To Thriving

Written ByHoward Parker

Love the art of creating a beautiful, self-contained world in your aquarium? Ever find yourself admiring a stunning piece of greenery and thinking, “I wish I could do that”? You’re not alone. Many of us in the aquascaping world are drawn to creating miniature ecosystems, and a terrarium is the perfect “dry land” project.

But it can feel intimidating. You might worry about choosing the wrong plants, getting the soil right, or the dreaded fear of overwatering. I promise you, it’s easier than it looks, and the skills you’ve honed as an aquarist give you a huge head start.

This guide will show you exactly how to make an open terrarium from start to finish. We’ll break down the simple science behind it, cover the essential supplies, walk through the crucial layering technique, and share a straightforward care routine. Get ready to create a stunning, low-maintenance piece of living art for your home.

Why an Open Terrarium? The Surprising Benefits for Aquarists

As aquarium keepers, we’re used to the constant cycle of water changes, filter maintenance, and parameter testing. An open terrarium offers a wonderfully different, yet familiar, kind of joy. It’s all about creating balance in a different medium.

The core of this project is understanding one key difference: an open terrarium is not a sealed, humid environment. It has an opening at the top that allows for excellent air circulation. This makes it the perfect home for plants that prefer drier conditions, like succulents and cacti.

Here are some of the fantastic benefits of how to make an open terrarium:

  • Extremely Low Maintenance: Forget weekly water changes! Open terrariums need watering only every few weeks, making them a perfect, low-stress addition to your home.
  • Prevents Root Rot: The open top allows moisture to evaporate, which is crucial for drought-tolerant plants. This design naturally prevents the number one killer of succulents: soggy roots.
  • Aesthetic Versatility: From sleek, modern glass bowls to rustic repurposed jars, an open terrarium can be styled to fit any decor. It’s a piece of living sculpture.
  • Perfect for Beginners: Don’t worry—these plants are incredibly forgiving! They thrive on a bit of neglect, making this a fantastic entry point into the world of terrestrial plants.

Gathering Your Supplies: The Eco-Friendly Terrarium Toolkit

Just like setting up a new tank, gathering your materials beforehand makes the whole process smooth and enjoyable. You likely have some of these items around your home already. This is a great opportunity to build a sustainable and eco-friendly how to make an open terrarium project by repurposing materials.

Here’s your checklist:

  • A Clear Glass Container: Choose a vessel with a wide opening. Bowls, wide-mouthed jars, or even an old fishbowl work perfectly. The key is easy access and good airflow.
  • Drainage Layer: Small stones, pebbles, polished glass, or lightweight LECA (Lightweight Expanded Clay Aggregate) work well. This layer creates a reservoir for excess water to drain away from the roots.
  • Activated Charcoal: Sound familiar? Just like in your aquarium filter, a thin layer of activated charcoal helps to filter impurities from the water and keep the soil fresh, preventing any unpleasant odors.
  • The Right Substrate: This is non-negotiable. You cannot use standard potting soil. Buy a pre-made succulent and cactus mix, which is sandy and fast-draining.
  • Your Plants: The stars of the show! We’ll cover which ones to choose in the next section.
  • Tools (Optional but helpful): Long tweezers or tongs for placing plants, a small spoon or scoop for soil, and a soft brush (like a paintbrush) to clean dirt off leaves and glass.
  • Decorative Elements: A top layer of sand, fine gravel, or small rocks adds a polished look and helps regulate moisture.

The Perfect Foundation: A Step-by-Step Guide to Layering

This is the most critical part of our how to make an open terrarium guide. Proper layering is the secret to a healthy, long-lasting display. Each layer serves a specific purpose, working together to create a thriving environment for your plants’ roots. Think of it as building your substrate in a planted tank—it’s the foundation for everything else.

Follow these simple steps in order:

  1. Step 1: The Drainage Layer

    Start by adding your drainage material (pebbles or LECA) to the bottom of your container. Aim for a layer that’s about 1 to 2 inches deep, depending on the size of your vessel. This creates a safety zone, ensuring your plant roots are never sitting in a puddle of water.

  2. Step 2: The Charcoal Filter

    Sprinkle a thin, even layer of activated charcoal directly on top of your drainage rocks. You don’t need much—just enough to cover the stones. This tiny layer is a powerhouse, working 24/7 to keep your terrarium’s tiny ecosystem clean and healthy.

  3. Step 3: The Substrate Base

    Now, add your succulent and cactus soil mix. The depth here is important. You’ll want a layer deep enough to comfortably house your plants’ root balls. A good rule of thumb is to fill the container about one-third to one-half full with soil. Don’t pack it down too tightly!

Choosing Your Champions: The Best Plants for an Open Terrarium

The golden rule of any community setup—whether it’s a fish tank or a terrarium—is to choose inhabitants with similar needs. For an open terrarium, you need plants that all enjoy bright, indirect light and dry conditions.

Mixing a moisture-loving fern with a desert-dwelling cactus is a recipe for disaster. Stick to the succulent and cacti family, and you can’t go wrong.

Here are some fantastic, beginner-friendly choices:

  • Haworthia (Zebra Plant): These are tough, slow-growing, and have striking patterns. They tolerate slightly lower light than other succulents.
  • Echeveria: Beautiful, rose-shaped succulents that come in a variety of colors. They love lots of light to maintain their compact shape.
  • Sempervivum (Hens and Chicks): These form charming, low-growing rosettes and are incredibly resilient.
  • Gasteria (Ox Tongue): Known for their unique, tongue-shaped leaves and tolerance for less-than-perfect conditions.
  • Small Cacti: Look for species like Thimble Cactus (Mammillaria gracilis) that stay compact. Just be careful with their spines during planting!

Pro-Tip: Just as you’d quarantine new fish, it’s a good idea to keep new plants separate for a week or two to ensure they are free of pests like mealybugs before adding them to your terrarium.

How to Make an Open Terrarium: The Assembly and Planting Process

You’ve gathered your supplies and built your foundation. Now comes the fun part: bringing your miniature world to life! Take your time with this process. It’s a creative endeavor, much like aquascaping.

  1. Plan Your Layout

    Before you start digging, arrange your plants on the surface of the soil to see what you like. Place taller plants in the back and shorter ones in the front. Think about color and texture contrasts. This is one of the most important how to make an open terrarium tips—plan first, plant second!

  2. Start Planting

    Once you have a layout you love, start with your largest plant. Gently remove it from its nursery pot and softly loosen the root ball with your fingers. Dig a small hole in the substrate, place the plant inside, and gently backfill the soil around its base. Pat the soil down lightly to secure it.

  3. Add the Others

    Continue this process with your remaining plants, using your tweezers or tongs to maneuver them into tight spots. Give each plant a little bit of space to grow; don’t overcrowd them.

  4. The Finishing Touches

    Once all your plants are in place, you can add a decorative top layer of sand or fine gravel. This not only looks great but also helps prevent the soil from splashing onto leaves when you water. Use your soft brush to gently whisk away any stray soil from plant leaves and the inside of the glass.

Long-Term Success: Your Open Terrarium Care Guide

You did it! Your terrarium is assembled. Now, how do you keep it looking beautiful? The good news is that following how to make an open terrarium best practices for care is incredibly simple. The biggest challenge is resisting the urge to over-care for it.

Light is Key

Place your terrarium in a spot where it will receive several hours of bright, indirect sunlight each day. A spot near an east-facing window is often perfect. Direct, scorching sun can burn the leaves, so avoid that.

The Golden Rule of Watering

This is where most people run into common problems with how to make an open terrarium. Succulents store water in their leaves and are extremely sensitive to overwatering.

  • Wait for the soil to dry out completely. You can check by sticking a wooden skewer into the soil. If it comes out clean and dry, it’s time to water.
  • Water the soil, not the plants. Use a small watering can or a syringe to direct water to the base of the plants, avoiding the leaves.
  • When in doubt, don’t. It is always better to underwater than to overwater. Depending on your home’s climate, you may only need to water every 2-4 weeks.

Frequently Asked Questions About Making an Open Terrarium

How often should I really water my open terrarium?

There’s no magic schedule. It depends entirely on your home’s temperature and humidity. The best method is to check the soil. For most, this will mean watering lightly every 2-4 weeks in the spring and summer, and even less (every 4-6 weeks) in the fall and winter.

Can I use plants from my garden?

It’s generally not recommended. Garden plants may carry pests and are not adapted to the specific indoor conditions of a terrarium. It’s best to purchase plants from a nursery that are suited for this environment.

Why are my succulents stretching out and looking ‘leggy’?

This is a classic sign of etiolation, which means the plant isn’t getting enough light. It’s literally stretching to find more sun. Try moving your terrarium to a brighter location.

Do I need to fertilize my terrarium?

Very rarely. Terrariums are slow-growing environments. If you feel the need, you can use a heavily diluted cactus fertilizer once a year during the spring growing season, but it’s often not necessary.

Your Journey into Greenery Starts Now

You’ve learned that the secret to a thriving open terrarium isn’t complicated. It boils down to three simple things: creating a layered foundation for excellent drainage, choosing plants that love dry feet, and learning to love them from a distance with minimal watering.

As an aquarist, you already possess the patience and observational skills needed to succeed. You know how to watch a system and respond to its needs. Now you can apply that expertise to a whole new, beautiful world above the water line.

So go ahead—get your hands dirty and create something amazing. Your stunning, living masterpiece is waiting to be built.

Howard Parker
Latest posts by Howard Parker (see all)
Related posts
  • Diy Terrarium Kit Ideas – Build Your Own Living Glass Garden
  • Mini Greenhouse Terrarium – Your Ultimate Guide To Growing Emersed