Charcoal for Terrariums

Charcoal in terrariums is optional, but definitely recommended. It is typically layered under the soil in closed-top terrariums. This helps with humidity and any funky smells. The Charcoal can have amazing benefits for plants. There are different types which have different uses. It can be hard to know which charcoal is best to use for your specific needs.

Charcoal for your terrarium should be porous and absorbent if you want it to get rid of any impurities. Activated charcoal also known as activated carbon is best for terrariums. It’s available in different forms such as powders, pellets and capsules

Activated charcoal is charcoal that has been treated with oxygen to open up the tiny pores between the carbon atoms. This makes it extremely porous. It is treated at very high temperatures. Furthermore, it is made by re-burning charcoal made from organic material, like hardwood or coconut shells. Resulting in a very fine and lightweight charcoal that is highly porous. 
It can absorb up to 200 times its weight. Additionally, it claims to absorb certain toxins. Also neutralizing certain chemicals and funky smells like compost. Furthermore, it’s used in outdoor soil to soak up pesticide or herbicide spills and used for filtering drinking water.
Activated charcoal is great for removing odors and toxins from soil. When a terrarium has a closed top gasses given off by plants and chemicals in the soil can build up. In fact becoming toxic to the plants. Bacteria can develop in the humidity and cause your closed terrarium to smell. 
When putting together a plant terrarium I add several layers. First, I add a layer of pea gravel. Second, I add activated charcoal. Third, I layer in some reindeer moss. Fourth, well draining potting soil. Finally, I top with gravel or pebbles. The activated charcoal can act as a filter to pull toxins and bacteria from the soil and water. As well as deodorize the terrarium. Using activated charcoal at the base of your terrarium or plant pot can help prevent overwatering, while keeping pests away. And minimizing the chances of fungal and bacterial growth.
Activated charcoal is great for plants growing in terrariums as it helps absorb extra water in plants. And traps carbon-based impurities from gases and liquids. Basically, the main use of activated charcoal is to keep the standing water “sweet”. Meaning not smelly, stinky, or rotten.
Horticultural charcoal is good for plants that prefer moist environments, such as ferns or orchids. A lightweight material that may improve poor soil by improving drainage and increasing the soil’s moisture-retaining capabilities. However, horticultural charcoal does not absorb water as well as activated charcoal. It does not have the spongy air pockets. Although, it still has excellent benefits for the soil and helps to keep the necessary nutrients in the soil.  
It helps by getting rid of stagnant water while increasing oxygen levels and the presence of beneficial microbes. Both activated charcoal and horticultural charcoal work to protect the soil and roots of a plant from fungus and bacteria. Which can lead to the plant rotting. Even though horticulture charcoal is occasionally recommended for terrariums. In fact it isn’t binding and provides very little benefit for terrariums.
Aquarium charcoal is obviously ideal for an aquarium that contains forms of plant life. This helps remove organic and inorganic materials that could be negatively impacting the quality of the tank water. Also, by absorbing pollutants and acting as a filter.
Grilling charcoal, BBQ charcoal, or charcoal briquettes are NOT recommended for plants. Alternatively, they are not as porous. Even worse, can end up increasing the ph levels of the soil. Additionally, they contain contaminants that can be harmful to plants. Unfortunately, they just do not have the same function as activated charcoal or horticulture charcoal.
Horticulture charcoal has many great qualities. But, unlike activated charcoal, it does not have spongy air pockets. Therefore, it lacks the ability to absorb odors or toxins. Conversely, horticultural charcoal does not absorb water as well as activated charcoal. Therefore, it’s best to use activated for Terrariums. 
Charcoal can be found at any aquarium or fish store. However, make sure it’s not some mixed-media filter charcoal. You only need charcoal if you plan on keeping an enclosed terrarium. Although, a lot of people say it’s not even necessary. I use it and also add them to my open terrariums as well. Besides that, I also add a few pieces to my succulents propagating in water. In particular, it slows the build up of algae.
I tried a few different brands and really liked this one found this here.
Charcoal for Terrariums
Charcoal for Terrariums

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