Or if there is no view to be obstructed, you could plant trees or large shrubs like olearia along the base and they will bush out over the stone gabions in time.
I have a gabion structure acting as a retaining wall in front of my house (see pic). It’s approx 50M long and tapering from 2M at one end to 4M at the other.Can you suggest a plant (or plants) with some colourthat I can plant at the base, that will grow it’s way to the top.
You are looking for disguise in this instance and it is best not to draw attention by having colour. The best bet would be ivy and/or Virginia creeper. The Virginia creeper is faster growing but will lose it leaves in winter, although the tracery of the branches will be good cover.