Posted: 02/06/2013 at 20:12
I second putting the tall ones at the back. Don't worry too much about it looking odd.
It might be a good idea to get batches of mixed sizes, or get the tall ones first, and plant from end to end or from back to front, rather than just getting a few things each time and trying to predict where they'll go.
Advice on soil type, position and eventual size can often be found on a seller's website, and Crocus for one has a handy "goes well with" at the bottom for inspiration.
Bit of a difference between 2.5m and 60cm there. I'd be careful with the feather grass as it looks like permanent foliage, and you don't want to "lose" other plants behind that. I note that the first one has "pheasant's tail grass" as a recommended companion, so maybe that and the "feather grass" could go around its base. Both also recommend one Allium or another, so consider a seasonal patch of those.
Now that's spectacular foliage. It says it forms dense shrubs. I'd say allocate it some space along the back and prune it every early spring to get it to grow dense and bushy and really fill that space.
Fancy foliage and 60cm high again, so I'd put that and some grasses with your giant Stipa and both the feather grasses with the Coprosma. The recommended bugle looks like a good one for either side.
Again, colourful year-round 60cm foliage, so mix in with the others at the front.
1.2m flowering some of the year. That'd go on both sides of and between the two tall things, for me.
The Salvias look a little delicate compared to the others, so I'm not sure how 'd mix them in. Maybe what you need is a dozen of each colour so you can put a broad row of them along the front edge. You could mix it with these:
... which should take over the flowering duty around the time the Salvias are quitting.
That's another recommendation for a "purple ball" Allium as a companion. They are lovely, but I'm not sure how I'd mix them in with your selection. If you planted them among the grasses you'd get the flowers in among the tops of the grasses, which probably isn't what you want. You could mix them with the Salvias to get different flower styles together, but they've got a similar flowering period so you wouldn't be extending that.
I think you need more of the smaller plants to create areas of them. I'd go for a whole bed containing the two big ones at the back with lupins around them, the grasses, heuchera and hebe through the middle and the Salvia, Allium and/or Dianthus along the front.