BTW, its in full sun, the picture is me standing at my front door facing south. I understand that terracing would be really lovely, but extremely costly - so not really an option.

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This slope doesn't look so steep that you will be having difficulty walking through it for maintenance, if you leave some space between plantings for access; heavily mulching to control weeds, and maybe using some flagstone stepping stones to step on. Your wish list of plants doesn't seem to include any evergreen shrubs or perennials to anchor the design and give it some structure year round. As a general recommendation, I'd suggest grouping multiples of each plant species and perhaps repeating them across the slope for some continuity. As I design for west coast or subtropical locations, I can't really give you great advice on how to lay out your wishlist of plants. What I can suggest is to consider how the various plants you like have different forms, and one can play uprights or taller lacey plants against lower mounds, and also consider playing off of foliage color and textures to give more interest when plants aren't in bloom. I've designed many colorful gardens with mostly perennials here on much steeper slopes and have them look great year round. The one benefit of a California climate is there are so many flowering perennials and herbaceous shrubs that are evergreen and/or even can be in full bloom in mid-winter. With some research on a wider plant list after visiting some of your better local gardens, I'm sure you'll have some good ideas of your own.

What I can recommend is to get out and visit some of the great public gardens you have in Pennsylvania, such as Chanticleer or Longwood Gardens to get some ideas on great planting combinations that work in your climate. The latest issue of Garden Design magazine has a feature on Chanticleer, worth picking up a copy to get you inspired.

Again, I can't emphasize too much that keeping a thick mulch/compost over any bare earth will help control both weeds and erosion. Good luck with your project.

This slope doesn't look so steep that you will be having difficulty walking through it for maintenance, if you leave some space between plantings for access; heavily mulching to control weeds, and maybe using some flagstone stepping stones to step on. Your wish list of plants doesn't seem to include any evergreen shrubs or perennials to anchor the design and give it some structure year round. As a general recommendation, I'd suggest grouping multiples of each plant species and perhaps repeating them across the slope for some continuity. As I design for west coast or subtropical locations, I can't really give you great advice on how to lay out your wishlist of plants. What I can suggest is to consider how the various plants you like have different forms, and one can play uprights or taller lacey plants against lower mounds, and also consider playing off of foliage color and textures to give more interest when plants aren't in bloom. I've designed many colorful gardens with mostly perennials here on much steeper slopes and have them look great year round. The one benefit of a California climate is there are so many flowering perennials and herbaceous shrubs that are evergreen and/or even can be in full bloom in mid-winter. With some research on a wider plant list after visiting some of your better local gardens, I'm sure you'll have some good ideas of your own.

What I can recommend is to get out and visit some of the great public gardens you have in Pennsylvania, such as Chanticleer or Longwood Gardens to get some ideas on great planting combinations that work in your climate. The latest issue of Garden Design magazine has a feature on Chanticleer, worth picking up a copy to get you inspired.

Again, I can't emphasize too much that keeping a thick mulch/compost over any bare earth will help control both weeds and erosion. Good luck with your project.