Plant Care

How to Build a Terrarium: A Complete Beginner's Guide There's something magical about a terrarium — a self-contained little world of lush greenery, living right on your desk or windowsill. Whether you've been eyeing those gorgeous glass jars on Pinterest or you want a creative weekend project that doubles as living home décor, building your own terrarium is easier than you think. At Divine Roots Botanicals, we grow many of the perfect plants for terrariums, and in this guide, we'll walk you through every step — from choosing your container to planting, decorating, and keeping your miniature garden thriving for years. What Is a Terrarium? A terrarium is a miniature garden housed inside a glass or transparent container. Think of it as a tiny, portable ecosystem. The concept has been around since the 1800s, when a London doctor named Nathaniel Bagshaw Ward accidentally discovered that ferns and mosses could thrive inside sealed glass cases. Today, terrariums are one of the hottest trends in indoor gardening — and for good reason. They're beautiful, low-maintenance, and perfect for small spaces like apartments, dorm rooms, and offices. There are two main types of terrariums, and understanding the difference is the single most important decision you'll make before you start building. Closed Terrariums A closed terrarium has a lid or stopper that seals the container. Inside, a self-sustaining water cycle develops: moisture evaporates from the soil and plants, condenses on the glass walls, and drips back down — just like rain in a tiny ecosystem. Closed terrariums are ideal for tropical, humidity-loving plants like Fittonia (nerve plants), mosses, and small ferns. Once established, they can go weeks or even months without watering. Open Terrariums An open terrarium has no lid, allowing air to circulate freely. This creates a drier environment that's perfect for succulents, cacti, and other plants that prefer less humidity. Open terrariums require more frequent watering than closed ones, but they're incredibly forgiving and a fantastic choice for beginners. Gathering Your Materials: Everything You Need Before you get your hands dirty, let's gather everything you need. The beauty of terrarium building is that you don't need fancy or expensive supplies — just the right layers in the right order. The Container Almost any clear glass container can become a terrarium. Here are some popular options: Glass jars — Mason jars, apothecary jars, or cookie jars (great for closed terrariums) Fish bowls — Classic round bowls work beautifully for open terrariums Geometric terrariums — Trendy hexagonal or diamond-shaped glass containers Wardian cases — The traditional terrarium shape, like a miniature greenhouse Large glass bottles or demijohns — For a stunning conversation piece The key is clear glass (so light can reach the plants) and a wide enough opening that you can comfortably get your hands inside — at least for your first build. The Layers A terrarium isn't just soil in a jar. It's a carefully structured system with distinct layers that work together to keep your plants healthy. Here's what you need: Drainage layer: Small pebbles, gravel, or expanded clay balls (LECA) — about 1–2 inches deep Separation layer: A thin piece of activated charcoal or sphagnum moss to prevent soil from settling into the drainage layer and to filter the water Activated charcoal: A sprinkle of horticultural charcoal keeps water fresh and prevents mold and odor — especially important in closed terrariums Substrate (soil): A well-draining potting mix appropriate for your plant type Decorative elements: Small stones, driftwood pieces, miniature figurines, or preserved moss for the finishing touches The Plants This is the fun part. We'll cover the best plant choices in detail below, but the golden rule is: choose plants that share the same environmental needs. Don't mix succulents (which hate humidity) with ferns (which love it) in the same container. Tools Long tweezers or chopsticks (for positioning plants in tight spaces) A small spoon or funnel (for adding soil neatly) A spray bottle (for watering and cleaning the glass) Paper towels (for wiping down the inside of the glass) Step-by-Step: Building Your First Terrarium Ready to build? Follow these steps and you'll have a finished terrarium in about 30 minutes. Step 1: Clean Your Container Wash your glass container thoroughly with warm soapy water and dry it completely. Any residue or bacteria on the glass can encourage mold growth down the road. This is a small step that makes a big difference. Step 2: Add the Drainage Layer Pour 1–2 inches of small pebbles, gravel, or LECA into the bottom of the container. This layer is critical because terrariums don't have drainage holes. Without it, water would pool at the bottom, drown the roots, and cause root rot. The drainage layer gives excess water somewhere to go, away from your plant's roots. Step 3: Add the Charcoal Layer Sprinkle a thin, even layer of activated horticultural charcoal over the drainage stones. This acts as a natural filter — it absorbs impurities, prevents bacterial growth, and keeps your terrarium smelling fresh. For closed terrariums, this layer is non-negotiable. For open terrariums, it's still highly recommended. Step 4: Add a Separation Barrier Place a thin layer of sphagnum moss or a piece of fine mesh screen on top of the charcoal. This barrier prevents your potting soil from sifting down into the drainage layer over time, which would defeat its purpose. Step 5: Add the Soil Add 2–3 inches of potting mix (the amount depends on your container size and plant root depth). For tropical closed terrariums, a standard indoor potting mix works well. For succulent open terrariums, use a well-draining cactus/succulent mix. Use a spoon or funnel to add the soil neatly — try to keep it off the glass walls for a cleaner look. Pro tip: Create small hills and valleys in the soil for a more natural, landscape-like appearance rather than a flat surface. Step 6: Plant Your Plants Now the creative part begins. Before placing anything permanently, arrange your plants on the table outside the container first to plan your layout. Consider: Place taller plants in the back (or center, if the terrarium will be viewed from all sides) Use shorter, spreading plants like Fittonia around the edges Leave some space between plants — they'll grow! Odd numbers (3 or 5 plants) tend to look more natural than even groupings Gently remove each plant from its nursery pot, shake off excess soil, and use your fingers or long tweezers to nestle the roots into the terrarium soil. Press the soil firmly around the base of each plant to secure it. Step 7: Decorate This is where your terrarium goes from "garden project" to "art piece." Add decorative elements like: Small river stones or colored pebbles Pieces of driftwood or bark Preserved sheet moss to cover exposed soil Miniature figurines (tiny animals, fairy garden accessories, or small stones) Step 8: Water and Clean Give your new terrarium a light misting with a spray bottle. For closed terrariums, you want the soil to be damp but not soggy — err on the side of too little water. You can always add more, but removing excess from a sealed container is tricky. For open terrariums, water lightly around the base of each plant. Use a damp paper towel wrapped around a chopstick to wipe any soil smudges off the inside of the glass. A clean container lets the light in and shows off your plants beautifully. The Best Plants for Terrariums Not every houseplant belongs in a terrarium. You need plants that stay small, tolerate the unique terrarium environment, and play well with neighbors. Here are our top recommendations — all of which we grow and ship at Divine Roots. Best Plants for Closed Terrariums (Tropical / Humid) Fittonia (Nerve Plant) — The ultimate terrarium plant. Colorful veined leaves in pink, white, and red. Stays compact, loves humidity, and thrives in low to medium light. Our Fittonia Terrarium Builder Bundle comes with 4 assorted varieties — everything you need for a stunning closed terrarium. Ferns (Boston Fern, Maidenhair Fern) — Feathery, delicate fronds that love the humid environment inside a closed terrarium. Compact varieties work best. For more on fern care, see our Boston Fern care guide. Pilea Baby Tears — Tiny, round leaves that create a lush carpet-like groundcover. Perfect for filling in gaps between taller plants. Read more in our Pilea care guide. Mosses — Sheet moss and cushion moss add a forest-floor feel and thrive in the constant humidity of a closed container. Episcia (Flame Violet) — Metallic-patterned leaves with small tubular flowers. A lesser-known terrarium gem that loves humid conditions. Check out our Episcia care guide for detailed growing tips. Best Plants for Open Terrariums (Dry / Succulent) Echeveria — Beautiful rosette-shaped succulents in pastel pinks, purples, and greens. We carry over 20 varieties, from Perle von Nürnberg to Blue Bird. See our Echeveria care guide. Sedum — Compact, textured succulents that add variety in form and color. Great as groundcover between larger specimens. Our Sedum care guide has you covered. Crassula — Including the popular jade plant family. Small varieties are perfect for open terrariums. More in our Crassula care guide. Sempervivum (Hens & Chicks) — Hardy rosettes that multiply by producing "chicks" around the mother plant. A terrarium that grows itself! Read our Sempervivum care guide. Caring for Your Terrarium: What to Expect One of the biggest advantages of terrariums is how little maintenance they need — but "low maintenance" doesn't mean "no maintenance." Here's how to keep your miniature garden happy. Watering Closed terrariums: After the initial watering, you may not need to water again for weeks or even months. Watch for condensation on the glass — a light fog is normal and healthy. If the glass is completely covered in heavy droplets and you can't see inside, open the lid for a few hours to let excess moisture escape. If the soil looks dry and there's no condensation at all, add a small amount of water with a spray bottle. Open terrariums: Check the soil every 1–2 weeks. Water sparingly when the top layer of soil feels dry. For succulent terrariums, less is always more — overwatering is the number one killer. If you're not sure whether to water, wait another few days. Light Place your terrarium in bright, indirect light. Near a north or east-facing window is ideal. Avoid direct sunlight — the glass acts like a magnifying glass and can cook your plants. If your space is low on natural light, a small LED grow light works beautifully. Pruning As your plants grow, they may start to outgrow their space. This is a good sign! Use small scissors or tweezers to trim back any plants that are pressing against the glass or crowding their neighbors. Regular pruning keeps the terrarium looking tidy and prevents one aggressive grower from taking over. Troubleshooting Common Problems Mold or fungus: Remove the affected area immediately with tweezers. Open the lid (if closed) for better air circulation. Reduce watering. A sprinkle of cinnamon powder (a natural antifungal) on the soil surface can help. Yellowing leaves: Usually a sign of overwatering. Check our guide on why plant leaves turn yellow for more detailed troubleshooting. Foggy glass (closed terrarium): Some condensation is normal. Heavy, persistent fog means too much moisture — open the lid for a few hours. Leggy, stretched plants: Not enough light. Move the terrarium closer to a light source. Pests: Fungus gnats are the most common terrarium pest. Allow the top layer of soil to dry between waterings to discourage them, or add a thin layer of decorative sand on top. Creative Terrarium Ideas to Inspire You Once you've mastered the basics, the creative possibilities are endless: Fairy garden terrarium — Add tiny figurines, miniature furniture, and a winding pebble path Moss-only terrarium — Create a moody, forest-floor landscape using different moss varieties and small stones Desert landscape — Use sand, small rocks, and succulents for a Southwestern-inspired open terrarium Carnivorous plant terrarium — A closed terrarium with Venus flytraps and sundews creates a fascinating conversation piece Gift terrariums — Build a terrarium in a beautiful jar for a personalized, living gift that lasts Shop Terrarium Plants at Divine Roots Ready to build your first terrarium? Start with plants that are proven terrarium performers: 🌿 Fittonia Terrarium Builder Bundle — 4 assorted nerve plants, perfect for one closed terrarium 🌿 Combo Terrarium Starter Plant — A hand-selected mix for terrariums 🌿 Full Fittonia Nerve Plant Collection — Browse all our colorful nerve plant varieties 🌵 Succulent Collection — Perfect for open desert-style terrariums 🪴 Carnivorous Plant Collection — For a truly unique terrarium experience 🌱 Small Indoor Plants — Compact plants sized right for terrariums Frequently Asked Questions How long do terrariums last? A well-maintained terrarium can last for years — even decades. The world's oldest known terrarium was sealed in 1960 and was still thriving over 50 years later. Closed terrariums are particularly long-lived because they create a self-sustaining water cycle. The key to longevity is starting with the right plants, proper layering, and occasional maintenance like pruning and mold removal. Can I use regular potting soil in a terrarium? For tropical closed terrariums, a standard indoor potting mix works well. For succulent open terrariums, use a specialized cactus and succulent mix that drains quickly. Avoid soil with added fertilizer (marked "feeds for 6 months") as the enclosed environment can cause fertilizer salts to build up. For the best results, check our complete guide to potting mixes. Do terrariums need sunlight? Terrariums need bright, indirect light — not direct sunlight. The glass walls act like a greenhouse and amplify heat, which can literally cook your plants in direct sun. A spot near a north or east-facing window is ideal. If you don't have good natural light, a small LED grow light set on a timer for 10–12 hours works perfectly. Why is my closed terrarium fogging up? Light condensation on the glass is completely normal and actually a sign of a healthy water cycle. If the fog is so thick you can't see inside, the terrarium has too much moisture. Simply remove the lid for a few hours to let excess humidity escape, then reseal. Over time, you'll find the right balance. Can succulents go in a closed terrarium? No — succulents need dry, well-ventilated conditions and will quickly develop rot in the humid environment of a closed terrarium. Always use an open, lidless container for succulents and cacti. For tropical plants that love humidity (like Fittonia, ferns, and mosses), closed terrariums are the way to go. How often should I water my terrarium? For closed terrariums, you may only need to water every few weeks to a few months — watch the condensation level as your guide. For open terrariums, check the soil every 1–2 weeks and water sparingly when dry. The number one mistake new terrarium owners make is overwatering. When in doubt, wait.