LECA - Lightweight Expanded Clay Aggregate.
1.5L, 3L and 5L bag options.
Use Leca instead of soil to grow your plants in! Roots easily grip to the substrate and reduce the risk of root rot compared to in soil. Just fill your pot with water up to below where the stem of the plant sits - dont cover the stem as this can cause it to rot. Add fertiliser to the water once and month and thats it!
See photos for examples of Hoya growing in Leca.