On the recommendation of someone on LAF (sorry forgotten who/when/where)
I used a green designed for plastic garden furniture. It works well as an undercoat,
then light spraying of other greens & browns, with some detail picked out with
thinned acrylics.
Mine has been around for over a year & is still going fine. It has helped that
everything is based in clumps & I NEVER pick them up by the foliage, but always
by their bases.