I’m no expert, but have lots of experience with garden beds and design. I don’t think your slope is so steep that you need a retaining wall. I’ve built them before with my husband. You could add more foundation plantings for structure that don’t flower, and intersperse with what you do have that flowers. I’d also add a small flowering tree to the left, something native. But idk where you are…..

Here are some pics of our slope in front of our cottage in the Midwest. The structural plants are the grasses, then the flowering plants pop at different times of the season. We get snow, so the grasses look great in winter with snow on them.

Check out books by Piet Oudolf for starters.

https://www.gardendesign.com/designers/piet-oudolf.html

I like the mix of things you have- kind of cottagey with lots of cheerful colors!

What zone are you in? And looks like a full sun planting situation?

I second the suggestion of a flowering tree behind and to the left of the bed... something with pretty pink blooms like a redbud or pink dogwood or a saucer or lily magnolia if those are good for your area. And perhaps two of some kind of medium sized evergreen shrub that also flowers might be nice too on that left side... Something like azaleas or rhododendron or daphne. Some other non evergreen bushy flowering plants like baptisia or butterfly bush or russian sage could be nice, too.

Some options to go with no wall

or

Or with retaining wall

How crazy is it to have a garden bed in the middle of the yard and no foundation plantings or beds? I would totally remove that bed and plant around the foundation of the house, reusing however many of the plants you already have. It’s a nice house, and it’s screaming Help Me to all of Houzz.

I like this idea

There is some foundation planting. It's just not very extensive. However, I would take issue with the assumption that every home must have compulsory foundation planting. Why? It's a phrase and a concept which I never even heard of until coming to Garden Web. It is by no means a universal sine qua non.

The OP has an island bed, not my favourite style, but a well know technique and absolutely fine if that's what they want. Here's a classic text on them. Perennials in Island Beds By Alan Bloom | Used | 9780571108923 | World of Books (wob.com)

The best part about that island bed away from the house is the view it provides from INSIDE the house, IMO. I think it must be lovely from front windows.

It's nice, I'm glad you like it. The flowers seem happy. I like how it blends in to the gentle green hill. For me, I'd simply replace the rr ties "as is, where is" with 6"x6" landscape timbers. The slope looks gentle enough to eliminate the middle row of timbers, if you don't need them to access the middle of the bed.

Another possibility would be to outline the whole bed with landscape blocks, raising the height of the front face to equal the back face. That would give you a larger raised bed (for improved drainage, better soil?), a sharper/more harsh edge to the planting area, and a low wall to sit on. But I don't think I'd like the giant "gash" across the slope.

@Mrs. Beasley thank you, I like your idea of more foundation plantings and a flowering tree. I'm in Canada in zone 3b. Your cottage yard is beautiful by the way!

@Hope Stewart thanks! Yes actually the house is facing north but this bed is far enough away from the house that it gets full sun. I'm in zone 3b, so maybe a flowering crab apple or something like that would work.

@Celery. Visualization, Rendering images thanks so much for those images and ideas, it really helps to visualize things! What software program do you use to do that?

@BeverlyFLADeziner thanks, I really like the arrangement and types plants in the first image!

@ShadyWillowFarm thanks, I see what you're saying, but since the house faces almost directly north it's tricky to find things that will grow in so much shade. These photos are from a couple years ago, I've since added some lungworts, ninebarks and dogwoods under the windows on the left, that seem to be doing ok, though not growing as quickly or as large as they would in a sunnier location.

@floral_uk z.8/9 SW UK thank you, I will check out that book!

@indianagardengirl so true, I love being able to see it from my kitchen window!

@nickel_kg thanks, those are definitely ideas we are considering. If we took out the middle row of timbers and just had one larger bed instead of 2, would you level it off or do you think it would be ok to have a bit of slope within the bed? Just worried about soil erosion, which is one reason I'm hesitant to just plant directly on the slope without any sort of border or retaining wall.

Raising the front wall is another consideration, but I agree it would look more harsh and I like how the bed seems to flow down the slope into the rest of the yard.

As long as you keep most of the bed covered with plants, and mulch any bare areas, I don't think erosion will be a problem. And, catmints and mountain mints make good, deer-resistant ground covers. :-)

The perennials you have must be deer resistant and they are all gone in the winter so aren't likely to be necessary food as any shrub could be come winter. This year we have damage to plantings we have never had. The more snow the harder it is to find food for deer so ANYTHING will be eaten!! You could easily go with just timbers as suggested. They too will rot eventually. Stone/bricks will shift and fall apart EVENTUALLY..so if the slope is gentle enough and just a few boulders or bricks defining your space does that trick I would go that way. Gardening is work and I see no reason to make it more work, if you don't need to.

Robyn, if you decide to add more grasses to your bed be sure they are clumping and not spreading. The prairie dropseed and switchgrasses are I believe both good for your zone, and are clumping.