Basically, are you just wanting to know where to plant all this stuff that you already bought? I suggest that you open the photo of you lot in Microsoft Paint and enlarge it some. (Actually, with the way GardenWeb does photos, we don't know what's its real size is. Maybe it's fine, but here, it looks tiny. view it at 100% in Paint and if you think it needs to be larger, you can "resize" it by %. Experiment. Do a "save as" in case you don't like what you produce and wish to start over.) Then you might use one of the paintbrush tools to plot in where you think you want to plant whatever. Just a dot is fine. (Research each plant--easy on Google--and decide what it could be. For example, the Burr Oak is a large shade tree. The red cedars are a large screen.) Just concoct something out of what you believe these things to be, scratch it out the best you can and post it here for feedback. You can mark trees with dots and label them with the text tool. (It only works when you are working on the drawing at the 100% scale. If you work on it at other sizes, the text tool is inoperable.) You can use the eraser tool to get rid of unwanted "junk" lines & marks on the drawing in order to clean it up a little. (for each drawing tool there is an adjustment scale to make it wider or narrower, so pick what works for you.)

Juliann, I'll post a site from the UK that has pictures of various types of gardens. This link goes to their Cottage Garden which they say is "contrived to look uncontrived". There are many other types of gardens there that might provide inspiration. Which plants you choose depends on which climate zone you are in. I'm in zone 3 so am somewhat limited in what I can grow. I'll post a pic of what I call my wild bird garden. It's an area in my large garden that has the birdfeeder and birdbath. I allow the flowers to go to seed for the birds so they self-seed. This area has changed over many years altho I initially seeded shasta daisies (the butterflies love them) and yarrow and planted a few established perennials. The yarrow seeds I planted were a mix of red, pink, and white, but the white resembles the wild yarrow we have so we pull it out and it's mostly now only tones of pinks and red. There are also Lamb's Ears because they seed all over my garden but I leave them in this wild area (the bees love them). There are a few other plants, a pink mallow that's 'weedy' but it fills the space and is quite pretty and we also have several lilacs here. Near that area there is also a drift of common old irises which we've allowed to spread. They are in the lower part of the rockery and I will eventually weed some of them out as the bloom time is not very long. If I were deliberately planting a wildflower garden I would not buy a wildflower mix as there could be invasive plants in it. I planted a mix about 14 years ago and still have Dame Hesperis (Dame's Rocket) altho pull out many every year and try to dead-head them ASAP before they seed. It's quite a weed in warmer climates. I would choose seeds of plants I like that are hardy but not invasive and mix them together. Another option is to plant in swaths with various plants and grasses hardy to your area. Keep in mind the moisture requirements of the plants as you decide. The area where I have shastas, mallow, and yarrow needs little watering and only a spring weeding so is easy care. Here is a link that might be useful: The Garden House

They do make biodegradeable anti-erosion mesh for these purposes. Keep in mind that as long as it is bare like that, it is going to erode. You could plant some ornamental grass and just not mow it. Vines are supposedly pretty good for erosion control, and there are many vines that have flowers...trumpet vines, etc. Just be sure not to plant one invasive in your area.

Hi monkeybolo, I'm outside Boston too and have a back yard similar to yours, as do several other people I know. I know what you mean about there being "hardly any options" for houses--people from other real estate markets have a hard time grasping just how ridiculous it is around here! Just wanted to share my experience. The slope atop my retaining wall has proved very difficult to convert into "garden"--it's just full of roots and weeds and my hours of efforts don't result in significant visual improvement. (My wall is higher than yours, though, and the hill has more trees.) But I have enjoyed treating the lower part of the yard as something like a "great room" with different zones; the walls surrounding it can actually be a positive thing in terms of making it a cozy retreat. It's different from the standard American back yard, more akin to an English garden. Once you decide on the house it may be helpful to consult a landscape architect or someone who can advise you on the deck and hardscaping to get the "bones" of the space in order. Good luck with your purchase!