A natural moisture balancer, activated charcoal is the secret ingredient in many of our terrariums. It helps keep things fresh by absorbing excess moisture and filtering out impurities. Whether you're layering it in a terrarium to help remove toxins or mixing it into a chunky soil blend to boost drainage and root health, this is one component where a little really goes a long way. Especially handy in humid environments or when building in a drainage layer for a pot without holes, it’s a small but mighty addition to any houseplant toolkit.