Light Conditions for Sealed Terrariums

Place your miniature garden in a well-lit location with no direct sunlight.

Direct sun can create a greenhouse effect inside the glass and rapidly overheat a sealed terrarium, destabilizing the internal ecosystem. I design terrariums using low to medium light terrarium plants, but even shade-tolerant species require consistent, indirect light to remain in balance.

For context, standard indoor LED or fluorescent lighting provides only about ~1% of full sunlight intensity. If you plan to have your terrarium in a space with mainly fluorescent lights (like in offices, away from a window) - chose low-light plants, and avoid a terrarium with moss (preserved moss cannot be used in sealed terrariums). In addition, natural light levels in Southern California drop by roughly half during winter compared to summer. Because of this seasonal change, it’s often beneficial to move your terrarium closer to a window in winter, while still keeping it out of direct sun to meet its terrarium light requirements.

You would know your terrarium doesn't meet its light requirements if the plants show etiolation, or stretched growth, meaning - there's a big gap, or "stretch stems" between the leaves, and they are less compact. In this case, move your terrarium to a brighter location.

When plants show etiolation, they're often times grow quick and start to fill the terrarium. If you don't like that look, prune some of the plants.

About once a month, rotate the terrarium half a turn. This simple practice promotes even light exposure and growth, prevents plants from leaning toward a single light source, and supports balanced, symmetrical growth over time.