Whatever tree you have at the right with the light green leaves, you've made it look insignificant by placing it smack on the edge of the bed. It would look better if the bed distinctly surrounded and visually supported it.

The overall bed line could be improved by making it fit the yard and include the shed. You could terminate it after it wraps the corner of the lawn, or you could extend it the length of the fence if you wanted bed along the side lot line.

Insofar as the hill being "brown," I agree that it would look better covered (and be protected from erosion) if it were planted and all green. Not to say that you couldn't have shrubs or perennials included in it in some designed fashion, but the main thing it needs is a durable, low groundcover to fill every spot not occupied by something else. What would work best would depend on where you are. And it would depend on what surrounds you in your neighbors yard. If the hill extends in to their yard and they already have a groundcover and it is working well, it would be good to use it so there no "fighting" (between plants or people) at the property lines. Many groundcovers can be started easily from plant pieces that include roots, during the growing season ... not when it's too cold. However, potted material can be installed so long as the ground is not frozen.

Your backyard reminds me of mine! While parts of mine strike some people as 'formal', it's a very calm and peaceful space. The basic lines are very simple - I agree with Yardvaark to include the shed, but I would bring the whole be forward to include the tree into the bed, rather than bring the tree visually forward by making the bed line bulge out around it. An easy way to improve the soil under the trees is to let all the fallen leaves in the fall stay under there to rot down and make soil! We rake all leaves (and pine needles in our case) into the garden beds and leave them there - it makes maintenance fast and easy and benefits the plants. It may be impossible to get much to grow deep under the trees. So plant towards the edges to provide screening and put a path(s) at the back for access and take advantage of the 'nothing will grow there' space! What is the silvery-green clump that is doing well under there? Can it be divided to use is other spaces too? I used to have Sweet Woodruff and wild ginger as a groundcover under the trees here. Much of it was killed in the nasty winter 2013/2014 when there was some water under there that froze for weeks and smothered things. Some of the groundcover is gradually coming back but will take a few more years to completely spread again. Some pictures that might give you some ideas....

Looking from the back porch in mid May:

Similar view after the leaves from the big ash tree fall in late October:

After leaves are raked into the garden areas:

Good luck - I think your space has lots of potential, especially if you start thinking of making that area a woodland-style garden.....

Many thanks to you both for Your thoughts! I hadn't thought about the edge "minimizing" the tree but I think you're absolutely right.

My feeling with bringing the bed further forward is that we will more of the same dirt pile look. The garden "bed" is already over 10 feet from edging to fence.

Woodyoak - that silvery green clump is a hosta that was transplanted from my mother's garden a month before haha. That's which is why it looks so healthy compared to the rest. Good eye!

I went and spoke to the neighbors about ground cover; they don't have any as they put a high, stone retaining wall with a "rock garden" after their hill garden refused to grow (did I mention the hill is north facing and we live in Ontario, Canada?) Not a good sign!

Any hardscaping ideas?

Also, woodyoak I really like your garden! And putting fewer leaves in bags sounds fantastic!

Caroline, I'm in Ontario too.... By brining the bed edge forward, you make space to plant beyond the worst of the tree roots. The grass appears to be growing well there so plants should too. If you plant some shrubs and taller perennials at the forward edge, they will help screen any 'naked' area behind them. That's what I did here. Deep under the pines is fairly barren, especially since the winter of 2013/2014 (the ice storm winter) but the forward screening planting hides most of that. Here, the beds on the south (left side), west and north sides beyond the rectangular lawn are about 20' deep.

Everywhere I've lived (zone 5 to 9) there are groundcovers that tolerate some fairly intense shade and competition from tree roots. Is that not the case in Ontario? Is it necessary to have "naked" areas below trees? On this site trees have been limbed up pretty well so let decent light below. It seems like getting groundcovers to grow shouldn't be a problem.

Yard - yes there are groundcovers that will grow there - some of them undesirable though..... My 'naked' areas are currently mainly due to winterkilled plants as a result of the dire winter of 2013/2014. Not everything died but the 'carpet' plants did. Even when there was a carpet of groundcover I had screening shrubs and tall perennials at the outer edge of the tree canopy. That made the area under the canopy feel very quiet and secluded, with the tall, straight pine trunks being pillars holding up the roof/canopy. It's hard to describe but I like the atmosphere of walking through that 'naked' space so would not want to eliminate it entirely. When I'm on a different computer, I'll see if I have pictures of what I'm describing.....

OK - I'm back on a computer with photos on it! Here are some pictures of the area under the pines that is pretty 'naked':

And here is what it looks like from the lawn side - you can see that the 'naked' interior is substantially screened:

And here are some views under the pines from June 2013 showing some of the groundcovers and other plants that were winterkilled that winter:

Woody, I know you are touting hiding emptiness with taller plants and claiming to like some emptiness. If they are paths, I can see the point of "empty." But if they are just bed, empty seems a whole lot less desirable than some type of low carpet. For example, in the picture immediately above, the groundcover on the left (I guess sweet woodruff) seems like a great, low cover for "empty" areas. The hosta seems fine if not too close to where one would walk. The empty area looks like a path and I would want to see it limited as such. But in your second picture from the top, all of the tall stuff at the edge of the lawn seems oppressive and cluttered to me. It seems also like you are creating a de facto end to your yard very near the edge of lawn, trying to hide what is beyond. The small building could just as well be in a neighbor's yard as yours. Why is this good to do in your own yard ... hide things from yourself? I'd rather see far into the bed and have screening occur near the perimeter for a less claustrophobic

Yard, we've hijacked Caroline's thread I think! :-)

The bare ground in the 2013 pictures is indeed paths. The Sweet Woodruff almost completely died out in the winter of 2013/2014. Bits are struggling to come back but it's a slow process. Some of the Geranium macrorrhizum fared better and that is a tough plant that Caroline might want to try.

I think we're having some semantic issues here :-) Hiding vs. screening etc. I like the 'mystery' of the paths by the shed leading off into 'unknown territory' behind the screening, enticing you to explore along the path to see what's there. Seeing far into the bed would also give you a good view of the neighbour-behind-us's unattractive metal shed on the other side of the fence! It's bad enough to see it in the winter when the leaves are off the shrubs; I don't want to see it in the warmer months. It's too dry under there to plant an evergreen screen of some sort to hide their shed - I've tried.... The yard is big enough that 'hiding' part of it doesn't feel claustrophobic.

Backyard layout (ignore the notes....) The property is 75' wide:

From the living room window in June:

The path around the lawn provides access, makes keeping the grass from spreading into beads easy, and provides a 'racetrack' for dog play! (You can see the neighbour's shed in the background in the picture below.)

when I moved here this dark and dry area was full of mulch..I put in plants but left a service alley next to the house..I'm writing to suggest planting hellebores..this photo just shows a glimpse behind the hydrangea..they reseed and have really filled in this area..there are hundreds that the leaves are hiding..

Woody, I cannot really get on board with the idea that tallish, bushy vegetation creates mystery and is alluring. It mostly says to me, "Keep out ... it's not a place to walk." I would rather see beauty front and center without any obligation of needing to go in and hunt it down in order to experience it.

Too, I think lack of light would be as big, or bigger an obstacle to establishing screening plants than would lack of water, since the latter is portable.