Can You Use Succulents in a Terrarium? - Plant Care Guide

While it's a common aesthetic choice, using succulents in a traditional, closed terrarium is generally not recommended due to their specific environmental needs. Succulents thrive in arid conditions with low humidity, excellent drainage, and ample airflow, which are precisely the opposite of what a sealed terrarium provides. However, you can successfully use succulents in an open terrarium or a similar well-ventilated display.

Why Are Closed Terrariums Not Ideal for Succulents?

To understand why succulents don't typically thrive in closed terrariums, it's crucial to grasp the fundamental differences between the environment a sealed container creates and the natural habitat of most succulents. This mismatch is the root cause of many problems for succulent terrarium arrangements.

What Conditions Do Succulents Naturally Prefer?

Succulents naturally prefer arid, desert-like conditions characterized by dry air, infrequent rainfall, and excellent drainage. These adaptations allow them to store water and survive in environments where other plants would quickly wilt and die. Replicating these preferences is key to their success.

Key natural preferences for succulents:

• Low Humidity: Succulents originate from regions with naturally low atmospheric humidity. Their thick, fleshy leaves are designed to retain moisture, and high humidity can lead to fungal issues.
• Excellent Drainage: In their native soil, water drains away very quickly, preventing their roots from sitting in soggy conditions. They often grow in rocky or sandy soils.
• Ample Airflow: Good air circulation around their leaves and soil helps to dry out moisture quickly, further preventing fungal diseases.
• Bright Light: Most succulents require plenty of direct or very bright, indirect sunlight to maintain their compact form and vibrant colors.
• Infrequent Watering: Due to their water-storing capabilities, succulents can go long periods without water and are very susceptible to root rot if overwatered.
• Temperature Fluctuations: Many desert succulents experience significant temperature drops at night, which they are well-adapted to.

These preferences highlight a stark contrast with the environment created inside a typical closed terrarium, setting the stage for potential problems.

How Does a Closed Terrarium Environment Differ from Succulent Needs?

A closed terrarium environment fundamentally differs from succulent needs by creating conditions that are diametrically opposed to what these plants require to thrive. This creates a challenging and often detrimental habitat for succulents.

Key differences created by a closed terrarium:

• High Humidity: A sealed terrarium traps moisture, creating a consistently high-humidity environment. This is the exact opposite of what succulents need and is a primary driver of rot and fungal diseases.
• Poor Airflow: The enclosed nature of a closed terrarium means very little to no air circulation. Stagnant, humid air is a breeding ground for pathogens and prevents the quick drying of soil and foliage.
• Lack of Drainage: Traditional terrariums often lack a drainage hole. While a layer of gravel is sometimes added, it merely creates a reservoir of standing water at the bottom, which is detrimental to succulent roots and can still lead to root rot.
• Fluctuating Temperatures (but often warm): While a terrarium can moderate some temperature swings, it can also quickly overheat in direct sunlight due to the greenhouse effect, further stressing succulents.
• Reduced Light Penetration: The glass enclosure can sometimes reduce light intensity, especially if positioned incorrectly, which can lead to etiolation (stretching) in light-loving succulents.

These differences explain why succulents, adapted to drought and dry air, quickly succumb to overwatering, rot, and disease when confined to the humid, poorly draining conditions of a closed terrarium.

What Problems Arise When Using Succulents in Closed Terrariums?

When succulents are used in closed terrariums, a predictable set of problems arises, almost always leading to the decline and eventual death of the plants. These issues stem directly from the mismatch between the plant's needs and the terrarium's environment.

Common problems include:

• Root Rot: This is the most prevalent issue. Without adequate drainage and with high humidity, the soil stays wet for too long, depriving roots of oxygen and creating conditions for fungal and bacterial rot.
• Fungal Diseases: High humidity and poor air circulation create a perfect breeding ground for fungal diseases like powdery mildew, black spot, and various molds on leaves and stems.
• Bacterial Soft Rot: Succulents can develop soft, mushy, discolored spots that quickly spread, caused by bacterial infections thriving in damp conditions.
• Etiolation (Stretching): If light levels are insufficient, succulents will "stretch" towards the light, becoming leggy, pale, and losing their compact, attractive form. This happens when plants desperately search for more light.
• Pest Infestations: While enclosed, pests can still get in. The humid, still air can exacerbate infestations of pests like fungus gnats, which thrive in moist conditions, or mealybugs, which are harder to detect and treat in a cramped, enclosed space.
• Overall Decline and Death: Ultimately, the combined stress from these factors leads to a weakened plant, discolored leaves (yellowing, browning, mushiness), and eventual death.

Therefore, for the longevity and health of succulents, it's best to avoid placing them in traditional closed terrariums.

What is an Open Terrarium and How Does it Work for Succulents?

Given the challenges with closed systems, the solution for succulent enthusiasts lies in the open terrarium. This type of setup maintains the aesthetic appeal of a terrarium while providing the vital environmental conditions that succulents need to thrive.

What Defines an Open Terrarium?

An open terrarium is essentially a glass or transparent container that has a wide opening, allowing for ample air circulation and the escape of excess moisture. Unlike its closed counterpart, it doesn't create a humid, self-contained ecosystem.

Key features of an open terrarium:

• Wide Opening: The most defining characteristic is a large, unobstructed opening at the top or side. This could be a wide-mouthed jar, a glass bowl, a shallow planter, or a container with a significant vent.
• No Lid (or removable/vented lid): Typically, open terrariums do not have a lid. If a lid is used, it's either kept off most of the time or designed with large vents to ensure continuous airflow.
• Mimics Arid Environment: The design specifically aims to mimic the dry, airy conditions of a succulent's natural habitat.
• Decorative Potential: They still offer the opportunity to create beautiful, miniature landscapes with various succulent species, decorative elements, and layered growing media.

This simple distinction in ventilation is what makes all the difference for succulent health and longevity in a terrarium-style display.

How Does an Open Terrarium Meet Succulent Needs?

An open terrarium successfully meets succulent needs by directly addressing the environmental deficiencies of closed systems. It prioritizes airflow, drainage, and controlled moisture, allowing succulents to thrive.

How it caters to succulents:

• Ample Airflow: The open design allows for continuous air circulation, which helps dry out the soil quickly after watering and prevents moisture from accumulating around the leaves. This is crucial for preventing fungal diseases.
• Low Humidity: Excess humidity easily escapes through the opening, maintaining the dry air conditions that succulents prefer.
• Controlled Watering: While still lacking a drainage hole in the glass container itself, the open nature allows you to accurately assess soil moisture with a soil moisture meter and apply water sparingly, preventing overwatering.
• Light Exposure: The transparent glass allows light to penetrate, and the open top often allows for better direct light exposure, which succulents crave.

By prioritizing these factors, an open terrarium creates a much more hospitable environment for succulents compared to a sealed one.

What are the Benefits of Using an Open Terrarium for Succulents?

The benefits of using an open terrarium for succulents are numerous, combining aesthetic appeal with practical plant health advantages. It offers a beautiful way to display these unique plants without compromising their well-being.

Key benefits include:

• Improved Plant Health: The most significant benefit is the drastically reduced risk of root rot, fungal infections, and bacterial diseases due to proper airflow and low humidity.
• Longevity: Healthy succulents in an open terrarium will live much longer and maintain their attractive form compared to those in a closed system.
• Aesthetic Appeal: Open terrariums allow you to create stunning, low-maintenance living centerpieces or decorative displays that showcase the diverse shapes, colors, and textures of succulents.
• Educational Opportunity: They can be a great way to learn about succulent care and create a miniature desert landscape.
• Versatility: You can use a wide range of glass containers, from shallow bowls to tall vases, to create different looks and accommodate various succulent sizes.
• Easy Maintenance: Once properly set up, an open succulent terrarium requires very little watering and attention, making it ideal for busy individuals or those new to gardening.

An open terrarium essentially provides the best of both worlds: the beauty of a terrarium display coupled with the vital environmental conditions that succulents need to flourish.

How to Build a Successful Open Succulent Terrarium

Building a successful open succulent terrarium involves carefully selecting the right container, layering appropriate drainage and growing media, choosing compatible succulents, and incorporating decorative elements. Each step contributes to creating a healthy and visually appealing mini-ecosystem.

What Kind of Container and Drainage Do You Need?

The container and proper drainage are foundational elements for a successful open succulent terrarium. Choosing wisely will set your plants up for thriving, while poor choices can still lead to problems even in an open system.

Container and drainage essentials:

• Container Choice:
  • Open Glass Vessels: Opt for wide-mouthed glass containers like large glass bowls, shallow dishes, geometric terrariums with large openings, or even repurposed clear glass containers. The wider the opening, the better the airflow.
  • Size: Choose a container that is large enough to accommodate the succulents you plan to use with some space between them for airflow.
  • Material: Glass is ideal for visibility, but ceramic or concrete containers with open tops can also work.
• Drainage Layer (Crucial!): Since glass containers usually lack drainage holes, creating an effective drainage layer is paramount.
  • Bottom Layer: Start with a 1-2 inch layer of coarse gravel, pebbles, or lava rocks at the very bottom. This provides a reservoir for excess water to collect, keeping it away from the roots.
  • Charcoal Layer (Optional but Recommended): On top of the gravel, add a thin layer of horticultural charcoal. This helps filter water and keep the terrarium fresh by absorbing odors and toxins. Look for horticultural charcoal for plants.
  • Mesh Screen/Landscape Fabric (Optional): A thin layer of mesh or landscape fabric between the charcoal and soil can prevent the soil from mixing with the drainage layers, keeping the system cleaner.

These layers work together to manage moisture in the absence of a traditional drainage hole, crucial for succulent health.

What is the Best Potting Mix for a Succulent Terrarium?

The best potting mix for a succulent terrarium is one that provides excellent drainage and aeration, closely mimicking the arid soil conditions succulents prefer in their natural habitat. Standard potting soil is too moisture-retentive.

Ideal potting mix components:

• Cactus and Succulent Mix: Start with a commercially available cactus and succulent potting mix. These mixes are specifically formulated to drain quickly.
• Additives for Enhanced Drainage: To further improve drainage, it's often beneficial to amend the cactus mix with additional gritty materials. Aim for a mix that is roughly 50% cactus soil and 50% drainage additives.
  • Perlite: Lightweight and porous, perlite significantly improves drainage and aeration.
  • Pumice: Similar to perlite but heavier and more natural-looking.
  • Coarse Sand: Horticultural sand (not play sand or beach sand) can be added.
  • Small Gravel/Crushed Granite: Can also contribute to drainage.
• Avoid Peat-Heavy Mixes: While peat moss retains moisture, too much peat can keep the soil wet for too long, which is detrimental to succulents.

The goal is a loose, airy, fast-draining mix that allows water to pass through quickly, preventing soggy conditions around the succulent roots.

Which Succulents are Best Suited for Terrariums?

When choosing succulents for an open terrarium, look for slow-growing, compact varieties with similar light and water requirements. This ensures they'll thrive together and maintain the aesthetic of your miniature landscape.

Best succulents for terrariums:

• Echeveria: Many Echeveria varieties, with their beautiful rosette shapes and pastel colors, are popular choices. Look for smaller, slower-growing types.
• Sedum: There are countless Sedum varieties, including ground cover types ('Stonecrop') and upright, compact forms. They are generally very hardy and forgiving.
• Haworthia: These unique, architectural succulents are tolerant of slightly lower light conditions than some others, making them versatile for terrariums. Varieties like Haworthia fasciata (zebra plant) are great.
• Gasteria: Similar to Haworthia, Gasteria species have thick, tongue-like leaves and are relatively slow-growing.
• Sempervivum (Hens and Chicks): These cold-hardy succulents are known for their resilience and propagation by "chicks" around the main "hen."
• Jade Plants (Crassula ovata 'Minima' or 'Gollum'): Smaller cultivars of jade plants work well.
• Air Plants (Tillandsia) (Bonus!): While not technically succulents in the same soil-growing way, air plants thrive in similar dry, airy conditions and can be beautiful additions to an open succulent terrarium, often placed on top of rocks or driftwood.

Avoid very large succulents that will quickly outgrow the space or succulents with vastly different care needs, as this will complicate maintenance.

How to Care for an Open Succulent Terrarium

Once your open succulent terrarium is built, proper care is essential to keep your plants healthy and beautiful. The key is understanding their needs for light, water, and occasional maintenance.

How Often Should You Water a Succulent Terrarium?

Watering a succulent terrarium correctly is the most critical aspect of its care, as overwatering is the leading cause of succulent demise. The frequency will depend on several factors, but less is always more.

Watering guidelines:

• Infrequent Watering: Water much less frequently than other houseplants. Allow the soil to dry out completely between waterings, plus a few extra days of dryness.
• Check Soil Moisture: Don't water on a schedule. Instead, feel the soil. Stick your finger 1-2 inches deep. If it feels moist, wait. A soil moisture meter can provide accurate readings within the terrarium.
• Application Method: Water carefully at the base of each plant, avoiding getting water directly on the leaves or pooling in the center of rosettes. A watering bottle with a long spout can be very helpful for targeted watering.
• Amount: Apply just enough water to moisten the top few inches of soil. Since there's no drainage hole, you don't want water collecting at the bottom.
• Seasonal Adjustment: Water even less in fall and winter when succulents are typically dormant.

If you are unsure whether to water, it's always safer to wait. Succulents are much more forgiving of underwatering than overwatering.

What are the Light Requirements for an Open Succulent Terrarium?

Light requirements for an open succulent terrarium are just as crucial as for individual potted succulents. Most succulents need abundant light to prevent stretching and maintain their vibrant colors.

Light considerations:

• Bright Light: Place your open succulent terrarium in a location that receives bright, indirect light for most of the day. A south or west-facing window is often ideal, but be mindful of intense afternoon sun that could overheat the glass or scorch delicate plants.
• Some Direct Sun: Many succulents appreciate a few hours of direct morning sun or diffused direct sun throughout the day.
• Avoid Low Light: Inadequate light will cause succulents to etiolate (stretch out, become leggy, with increased space between leaves) and lose their vibrant stress colors, turning pale green.
• Rotate Periodically: Rotate the terrarium every week or two to ensure all sides of the plants receive even light exposure, promoting balanced growth.
• Supplemental Lighting: If natural light is limited, especially in winter, consider supplementing with a full-spectrum grow light for 10-12 hours a day.

Adequate light is paramount for healthy, compact, and beautifully colored succulents in your terrarium.

What About Fertilizing and General Maintenance?

Fertilizing and general maintenance for an open succulent terrarium are relatively minimal but important for long-term health. Succulents are not heavy feeders, and less is often more.

Fertilizing and maintenance tips:

• Fertilizing (Infrequent):
  • Succulents in terrariums rarely need fertilizer.
  • If you choose to fertilize, do so very sparingly, perhaps once a year in spring or early summer, using a liquid succulent or cactus fertilizer diluted to 1/4 strength.
  • Too much fertilizer can lead to leggy growth or "fertilizer burn."
• Pruning: Remove any dead or dying leaves as they appear. If a succulent begins to stretch (etiolate) due to insufficient light, you can prune the leggy stem and try to re-root the top, but addressing the light issue is the primary solution.
• Pest Watch: Regularly inspect your plants for signs of pests like mealybugs or spider mites. If found, isolate the affected plant and treat with horticultural oil or insecticidal soap. Good airflow helps deter pests.
• Dusting/Cleaning: Occasionally gently dust the succulent leaves with a soft brush or puff of air to ensure they can photosynthesize efficiently. Clean the glass of the terrarium regularly for maximum light penetration and aesthetic appeal.
• Repotting/Refreshing: Over time, succulents will grow, and the soil might deplete nutrients. Every 1-2 years, you may need to refresh the soil, move larger plants to individual pots, or create a new terrarium.

With proper setup and minimal, consistent care, your open succulent terrarium can provide lasting beauty and enjoyment.