Hanging basket liner grass

A few weeks ago I decided to experiment with using hanging basket liner to represent rough grass. While I think the results are reasonable - the colour in particular is quite convincing as is, there are a couple of things I'm not too happy with - one is that there are quite a few dark green wiry bits in amongst the fibres which don't look very good (I should probably 'shop around' a bit for other liners), and the other is the rather unrealistic way the fibres seem to go in every direction no matter how much you work at teasing them into a more convincing upwards direction - maybe this is just par for the course with this technique. I might try to get hold of some traditional carpet underlay and experiment with that (I think Green Scenes supply it in small pieces - or does anyone know of a cheaper source?).