From the experts at Soil.Ninja:
 
Ficus is a large genus of plants that inhabits a lot of different environments. The species that we tend to cultivate in the home are either used to a semi-epiphytic habit or are totally terrestrial and that is what this mix perfectly caters to.
 
Using a blend of: Coco Coir, Perlite, Bark, Sand, Activated Charcoal, Worm Castings
 
The marrying of activated charcoal and sand in this slightly denser mix provides excellent drainage whilst being detoxifying the resilient yet troublesome roots of our beloved Ficus. The sizable bark content in the blend also serves to suit those Ficus species that are semi-epiphytic growers, as well as contributing to a little extra moisture retention to this sandy mix.
 
But don’t use this blend just for Ficus alone, though we name with a genus in mind there are plenty of other plants that will adore this blend as it is or with minor alteration. Some of the plants that will adore this next include Rubber Plants, Peperomia, Bonsai, Citrus Plant, Fiddle Leaf Fig, Palm, Avocado Plants and even Hibiscus.