We rolled the tradescantia into a carpet and rolled it to the path below. We planted the bank in native plants, including Renga Renga lily, ferns, kotukutuku, wineberry, plastered the bank in wet newspaper and barked.
A test piece we did earlier in the year is looking quite good, with the odd breakout but seems to be working.
The bank had been a dumping ground for concrete slabs and builders rubble and garden waste for decades, but borders a nice native bush patch. I'm sure it will look great in a few years.
We still have a few hundred square meters to go!