Richard Freeman, Designed Ecosystems
For high-performance horticulture, I prefer to replace the standard peat-lite (various combinations of peatmoss and perlite) with an aerated blend of aggregates and fibers made from renewable resources. This blend is a “sterile medium.”
To this highly-aerated sterile blend, I add another blend of substrates I call bio/char — a combination of high-quality composts, biochar and nutrient amendments.

In the example I’m demonstrating here, to make bio/char, I used double-screened biochar (grey tub), thermal compost (green tub), worm compost (blue bucket) and amendments (clear plastic jar).


I used the tarp method of blending. I started by pouring a layer of double-screened biochar. Then I added a layer of thermal compost.

On top of the thermal compost I added a mixture of worm compost and amendments.

Using the tarp method, I thoroughly blended the components.
Next, I evenly moistened the blend and stored it in a ventilated tub (like the shown above) for three days.
To blend the aerated sterile medium to the bio/char, I used the tarp method.

I began by pouring a layer of parboiled rice hulls onto the tarp. Then I poured a layer of processed coco coir. On top of the coir I poured a layer of bio/char.

I then blended the components thoroughly, moistened them and blended again.
After blending the horticulture media, I stored it for three days in a ventilated tub (as above).
Do you have questions or comments? Please email me and I’ll be happy to answer them.