Posted: 27/08/2015 at 17:36
the miscanthus, all of them, grow big. I divide mine every 3 years or so. Do you want to plant perennials with them? I.e. Heleniums, rudbekias, veronicastrums, whatever?
my big grasses are at least 10 to 15 feet apart....to enable perennials between and to create varying heights and textures. as I said, you can divide these to keep under control and you can move them too if you want to. You prob will so it is not crucial ...you can change spacing
unless you want a prairie grass planting where nothing else but these grasses will be planted then you can space 3 to 5' apart.
pennisetums too can spread quite rapidly although much shorter. Again be prepared fo lift and divide every 3 years or so but these can be 3' away from other perennials.
carex testacea is compact....will enlarge every year. I again divide to provide more clumps
I could post some pictures to illustrate their scale and habit right now.