Posted: 27/05/2014 at 20:10
Red, it's lovely. Maybe a climbing rose or clematis up the pergola posts and the arches. Paint the fence, then find some clematis to break up the expanse of fencing.
As for cutting's, the scabious can be propagated by division in autumn. I find that one planted now is usually three or four by autumn. The gaura, can be propagated by root cuttings or simply digging some of it up taking a few roots and potting them up, mine go mad every year and I have to spend an afternoon in autumn thinning it out. Lythrum, again by division and the Agastache, it's far easier than trying cuttings.
As for alliums see the link to the RHS below.
You've done a great job so far, just have confidence and don't be afraid to make mistakes, we all do as long as it looks good to you, then you'll be happy with it.
Not sure if slugs will dislike brass, I think not as brass isn't conductive.
The front garden, I'll let other's give you their suggestions.