If you've ever built a terrarium, you've probably noticed a layer of small clay balls at the bottom of the container. These are called LECA, which stands for Lightweight Expanded Clay Aggregate.

LECA is made by heating natural clay at high temperatures, causing it to expand into lightweight, porous spheres. These clay balls are commonly used in terrariums, hydroponics, and indoor gardening because of their excellent drainage properties.

Why Is LECA Important in a Terrarium?

One of the biggest challenges in a closed terrarium is managing excess water. Without proper drainage, moisture can accumulate around plant roots and lead to root rot.

LECA helps solve this problem by creating a drainage reservoir at the bottom of the terrarium where excess water can collect away from the roots.

Benefits of Using LECA

• Improves drainage
• Helps prevent root rot
• Stores excess moisture below the soil
• Promotes healthier root systems
• Supports long-term ecosystem balance
• Lightweight and natural material

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Where Does LECA Go?

LECA is typically the first layer added to a terrarium. It sits beneath the activated charcoal and soil layers, creating a foundation for the ecosystem.

A typical closed terrarium layering system looks like this:

1. LECA (drainage layer)
2. Activated Charcoal
3. Soil Substrate
4. Plants and Moss
5. Decorative Materials

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Is LECA Necessary?

While some terrariums can be built without it, LECA is highly recommended, especially for closed ecosystems. It provides an extra layer of protection against overwatering and helps maintain a healthier environment for tropical plants.

At Terrart NYC, we include LECA in our workshops and DIY Terrarium Kits because it helps create stronger, longer-lasting ecosystems with minimal maintenance.

A good terrarium starts from the ground up, and LECA is one of the key ingredients that helps keep the entire ecosystem thriving.