Succulents can be found in over 60 different plant families, and each has its unique beauty. Although succulents and cacti are hardier than your average houseplant, their soil requirements are quite particular, and you should ensure that your terrarium soil mix will allow your plants to thrive.
The best soil options for a succulent terrarium should provide aeration and drainage and not retain water. Pre-mixed soil brands such as Bonsai Jack, Hoffmans, Terra Green, and Fat Plants offer a great balance of minerals to organic ingredients. Miracle-Gro and Superfly are also good pre-mixes.
The best soil for your terrarium will take into account your succulents’ natural habitat and attempt to mimic the soil composition. Understanding your succulent’s unique needs will allow you to choose the perfect soil for your terrarium better. Read on to learn your succulent’s requirements and the six best options to satisfy them.
What Exactly Is a Succulent?
The word succulent comes from the Latin word sucus, which means juice or sap and refers to plant species with thickened and fleshy parts such as leaves or stems that function to retain water in arid climates or soil conditions. There are roughly sixty different plant families that contain succulents in botanical classification and refers to a broad diversity of plants.
The term succulent may be a tricky one to definitively pin down because it refers to a species characteristic rather than a definition of a family or genera of plants in botanical terms. While horticulturists distinguish between cacti and succulents, in botanical terminology, cacti are defined as succulent.
To eliminate confusion in this article, we will refer to succulents in the broader botanical definition to include both cacti and succulents when discussing succulent terrariums.
How Do Succulents Survive in the Wild?
A popular misconception regarding succulents is that they are desert plants when they are most commonly found in semi-arid areas. These areas typically experience regular and predictable rainfall (although not necessarily frequent). The primary role of succulents is water storage, and their water-holding organs may reach between 90-95% capacity.
The diffuse and shallow root system of succulents is adapted to rapidly rehydrate when in contact with the semi-arid landscape’s short and intense rainfall. Succulent roots are adapted to take advantage of these scarce rainfall events by absorbing up to 50% of the water.
Alternatively, their taproots function more as an anchoring point than an absorptive area. The remobilization of water is facilitated by elastic cell walls and the secretion of polysaccharides into the plant cells in mucilage. These unique characteristics of a succulent necessitate a very specialized type of soil to ensure that they not only survive but thrive in your terrarium.
What to Look For in Soil Best for a Succulent Terrarium
Succulents require less maintenance than other plants and are forgiving for infrequent waterings and general neglect. However hardy and forgiving they might be, succulents are notoriously fussy about what kind of soil they find themselves planted. The best soil for succulents mimics their native habitat and suits their particular evolutionary requirements. The most important is water and drainage.
In their native habitat, succulents tend to thrive in sandy, gravelly soil and are often found in rocky areas or crevices. Their native climate is usually one of intense and infrequent rainfall that dries out rapidly after showers. Drainage is essential and involves water quantity, sunlight, and soil structure to mimic your succulents’ ideal habitat.
Drainage in Terrariums
Drying time is paramount and involves a balance of these factors, and as a starting point, your terrarium should ideally have some form of a drainage hole. Although succulents may thrive in an all-glass terrarium without drainage, watering becomes problematic.
One sure way to kill your succulents is to let their roots sit in soggy conditions. Having gravel at the base of your terrarium is no sure-fire solution, as water can build up in the pockets between the stones and allow bacteria to breed and pose an even greater risk to your plants.
If your terrarium has no drainage holes, you need to ensure you pay extra attention to your watering techniques. Allow your soil to dry completely between waterings, use a syringe or a spray bottle when watering, and ensure that the substrate is moist but not waterlogged.
This all-in-one kit from TerraGreen has all the ingredients to start your succulent terrarium the proper way. The all-in-one kit eliminates the nuisance of having to buy different components, which generally come in bulky sizes and provide more than you need. The kit comes in small, medium, and large size options to suit your chosen container size.
The kit contains pea gravel to provide drainage in your soil and charcoal to ensure that your succulent’s roots stay dry. For a perfect combination, the kit contains organic soil with the ideal ratios of materials to ensure that your soil does not clog or inhibit root growth. They include colorful sheet moss that is both a functional and aesthetic addition to your home terrarium.
The assembly is a straightforward process and can be accomplished easily within minutes:
- Place your pea gravel in the bottom of your container for essential drainage.
- Add a thin layer of soil mix to anchor your succulents.
- Place a layer of activated charcoal to remove toxins and odors.
- Place the rest of your soil mix.
- Position your cacti and succulents in the soil for an eye-catching design.
- Add river rocks for decor.
- Position moss on the uppermost layer for a bright visual (and to absorb moisture.
This pre-mixed succulent soil mix is perfectly suited for growing your succulents in your indoor terrarium. The blend is specifically formulated to provide your plants with soil that is both fast draining and well aerated.
Their soil mix is made up of a suitably coarse combination of organic and non-organic materials that mimic your plant’s natural habitat. The mixture provides the best drainage, water retention, and nutrient absorption for your plants while allowing aeration for your cacti roots. The mix includes:
- Japanese Akadama
- Pine bark
The SuperFly mix is available in handy sizes grade according to your container size for easy measurements in 1.25 quart (four cups), 2.5 quarts (eight cups), and 12-quart (3 gallons) bag sizes. These packages are resealable for future use and come with a full money-back guarantee.
The miracle Gro succulent mix is designed to mimic your plant’s natural habitats for optimal growth. The mix contains forest materials, coarse sand, and perlite to ensure that water is adequately drained and prevents soil impaction leading to stifled growth or rot. As a bonus, this particular potting mix is enriched with Miracle-Gro nutrients that provide your plants with food for up to six months.
You may buy this mix in an 8-quart (2 gallons) bag, which is more than suitable for two 8″ containers and has been specifically formulated for the particular need of succulents grown in an indoor environment. This is a great option for beginners because it takes the guesswork out of making up your own soil.
This Florida-based company has built up an excellent reputation for its quality soil mixes. Bonsai jack’s soil mixes are state inspected and lab-tested regularly to ensure the quality of its ingredients so you have peace of mind that your mix won’t contain harmful pathogens that may affect your plants. Bonsai Jack’s proprietary soil mix is formulated to provide fast drainage and a balanced 5.5 pH level on which succulents and cacti thrive.
Bonsai Jack Succulent and Cactus Soil – Jacks Gritty Mix #111 – 2 Quarts – Fast Draining – Fight Root Rot – Optimized pH is a great choice and easy to purchase from Amazon.
The Bonsai Jack mix is a balanced ratio of organic to inorganic to ensure aeration and proper nutrient uptake for your indoor succulents. The all American sourced ingredients include:
- 33% Pine coir for water absorption
- 33% ¼ calcined clay
- 33% Monto clay with ¼” particle size.
You can be sure that your mix is sterile with the pre-washed and screened soil mix without any nasty surprises. The product is available in 2-quart (½ gallon) up to 112 quarts (28 gallons) containers to suit your terrarium needs.
Based in San Diego, California, Fat Plants has a solid reputation in the horticultural community for providing high-quality plant-soil mixes. The mix contains a healthy time-release nutrient mix that provides all the nutrients your succulents and cacti require for up to 6 months. Their light, aerated mix retains low moisture and allows the drainage essential for succulent and cacti growth.
Suitable for indoor and outdoor growing conditions, this mix is versatile and can be used for multiple growing applications. The proprietary blend is a balanced ratio of organic to inorganic materials and is pH balanced to suit your succulents’ slightly acidic preferences. The mixture contains:
- Coarse sand
- Worm castings
- Bone meal.
The Fat Plants soil comes in various handy sizes, so you won’t be forced into buying more than your need for your terrarium. These options range from ½ quart (½ gallon) containers to the more hefty 8 quarts (2 gallons).
Hoffman’s cactus and succulent soil mix are formulated to suit various succulents and cacti, whether jungle or desert cacti species. The coarse mixture provides superior drainage and aeration and has a balanced pH suited to your succulent terrarium.
The blend includes a variety of organic and inorganic materials to provide a balanced growing medium, which includes:
- Coarse sand
- Canadian sphagnum moss
The Hoffmans are available in 4 quarts (1 gallon) containers, so you need not buy bulk containers if your terrarium requirements are less. The packaging also includes some handy growing tips for you to grow your indoor succulents.
Critical Factors in Choosing Your Succulent Soil
Succulents grow well in soil that would be considered inappropriate for other houseplants. An ideal soil for your succulents would allow easy root growth and easy air and water exchange for evaporation and drying after watering.
Depending on the type of succulents, the organic and inorganic ratios may differ, but most succulent mixes contain 25%-50% organic matter combined with inorganic materials.
Organic vs. Inorganic Balance
Organic materials are essential in your succulent soil to increase water retention and the plant’s ability to absorb nutrients. Common organic matter includes:
- Sphagnum moss or peat
- Coconut coir
- Leaf or bark shreds
Inorganic matter is essential in your soil mix by providing aeration and porosity and aiding water drainage. Succulents struggle particularly in sticky and compact soil without a balance of inorganic matter because it retains moisture at the roots and makes it difficult for your plant to respirate properly.
Two of the most common inorganic materials in succulent soil are perlite and pumice:
- Perlite is a type of volcanic glass with a high water concentration typically composed of obsidian. Perlite is created when the glass is heated under high temperatures until the water is released. The medium expands to up to 16 times its original size.
- Pumice is also a type of volcanic glass that is a cooled larval foam. The pumice regulates water absorption and provides aeration for the soil.
Other inorganic soil components include:
- Crushed granite
- Turface (fired clay)
There are many great pre-mixed succulent soil options available over the internet or at your local nursery, but if you choose, you may use your own potting soil on hand. All-purpose potting soil must be altered, however, to suit the unique need of your succulents. It is best to use a light and porous soil mix and not heavy garden soils. Moisture control potting soils are unsuitable as they often contain vermiculite that retains water, which is a no-no for succulent health.
To make up your own succulent soil mix, you would have to include a coarse sand mix, not fine sand or beach sand, as it tends to clump. Once you have your coarse sand, you are ready to make your succulent soil mix for your terrarium.
The optimal range for your succulents’ pH is slightly on the acidic content of 5.5pH, but they can tolerate a pH range between 4 and 6.5 pH. Alkaline soil is more harmful to your succulents than one that is overly acidic. You should bear the pH needs of your succulents if you are buying pre-mixed soil. You may also test your soil’s acidity if you are concerned that your terrarium plants are not thriving using electronic testers, pH strips, or chemical colored dye tests.
Your succulents should only be fertilized with low nitrogen fertilizer and high phosphorus and should be diluted half strength to the directed water to fertilizer ratio. Because succulents and cacti are slow growers, you don’t want a build-up of chemicals in your soil, so you should flush your plants with plenty of water. Succulents are more damaged by the frequency of watering than the volume.
You only need to fertilize your cacti once or twice a year during the late spring of the summer or when your cacti are in active growth. Succulents follow the same process, but you should aim to increase your fertilization frequency to three or four times a year in the summer months.
Rather than compost, manure tea makes a great additive to your succulent soil, or Miracle-Gro is a commercial alternative. Some succulent growers swear by liquid tomato fertilizer in half dilutions for exceptional growth. Ultimately, it is your decision which fertilizer is best for your terrarium.
Making Your Own Succulent Soil Mix
Creating your succulent soil mix is as easy as mixing your base ingredients with your hand or a trowel. If you have leftover mix, be sure to place it in a sealed container or plastic bag for future use. You will need:
- 3 parts potting soil
- 2 parts coarse sand or surface
- 1 part perlite or pumice
Here is an informative video about creating your terrarium mix if you would like to make your soil mix at home:
If you are new to succulent care and would rather purchase professionally pre-mixed soil, there are some great options available on the market for you to use. We have included all-in-one starter kits for those of you who would like all the ingredients to start your terrarium.
Starter kits are great for novice succulent growers and take the guesswork out of creating your soil or shopping for the various ingredients to make up your soil.
Succulents are a decorative and unique species and require less care than other houseplants. To ensure that your terrarium plants thrive, you need to provide them with the right soil. Whether you buy a pre-mix or DIY, your succulent soil should provide drainage and aeration and the correct pH, and your terrarium will remain a feature you may enjoy for years to come.