Terrarium Growing Media
When building a terrarium it is immensely important to provide plants with a growing media best suited for their needs. There are many different types of media available for use, varying in their characteristics and aesthetic nature. Understanding the basics of terrariums, the importance of having a high-quality growing substrate, and the nuances between the available options will help you choose the most appropriate growing media.
In the simplest terms, a terrarium is a glass container or vessel used to grow plants indoors. By design, their setup creates a self-contained, micro-ecosystem that functions with little maintenance or assistance from the owner.
They can either be fully enclosed to grow tropical plants that need high humidity, or they can be partially open to house cacti or succulents that require a more arid environment.
Importance of Quality Growing Media
Whether you are growing outside in containers, or inside using a terrarium, one of the most critical aspects when growing plants is to use an appropriate, high-quality growing medium or substrate.
The growing media is important for plant growth because it creates pockets of “empty” space around the roots for air allowing them to breathe; it serves as a holding tank of moisture and nutrients for the roots, and it provides support to plants by giving the roots a substance to anchor into. Some substrates also slowly release plant essential nutrients from their organic materials over time, helping to meet the nutritional needs of the plants.
How well your plants grow, and how successful your terrarium is overall, will depend greatly on the quality of growing media you use, if it is befitting of the type of terrarium you are building, and the specimens of plants you are growing.
Different Types of Media
So what makes a good growing media for your terrarium then? With many options available for purchase through online and brick and mortar retailers, it’s easy to get overwhelmed with all the choices.
Different growing situations and even different plants fare better using different growing mediums; understanding the characteristics of the different medium options helps you choose what type is best for your needs.
Here’s a quick rundown of the most commonly used terrarium growing media:
- Potting soil really isn’t soil at all, but rather a soilless mixture that contains peat moss or coconut coir, wood materials, and either perlite or vermiculite. This lightweight mixture retains water well and resists compaction, keeping plenty of airspace open around the roots. It is the most commonly used growing substrate for all container plants.
- Coconut coir is similar to peat moss in that it’s very light and holds a tremendous amount of water. Composed of the brown and white fibers fond between the shell and outer coating of the coconut seed, coconut coir is a renewable resource, making it an environmentally conscious choice.
- Spaghnum peat moss is formed when decaying plant materials in poorly drained areas such as bogs accumulate over time. It is light in nature and can retain a tremendous amount of water (10 to 20 times its weight) while still managing to drain well. Natural fungistatic properties inhibit fungi growth also, making it a great choice for high humidity terrariums.
- Sand is very popular when building open terrariums that house cacti or succulents. It is often used to bury the rootball on these desert-loving plants or as a topdressing to create the look of an arid environment.
- Rocks/stones/gravel can either be used as a growing media or a topdressing material, depending on the design idea. Since they hold little to no moisture they are appropriate for cacti and succulent terrariums.
- Bark chips are a great substrate to use when planting specimens that don’t rely upon regular “soil” for their growth. Air plants and orchids both do well when anchored into bark chips. This media can also be used to topdress the surface of your terrarium to create a more finished aesthetic.
When building your own terrarium it is important to start with the growing media best suited for your project. While potting soil is the most common substrate used, there are other options such as sphagnum moss, coconut coir, sand, rocks, and bark chips. Knowing the needs of your plants and the properties of the different growing media will help you to correctly pair the media to your project.