I am with Dottie that you would do well to plant next fall (mid-September to late October in your zone) to allow root growth but have less stress on the plants due to shorter, cooler days. Regardless of what you plant, it will need regular water until the ground freezes. This season you can evaluate the site and plan so that you are ready come fall. I also agree with Dottie about voles - you could ask on the perennial forum or on the shrub forum (whatever type of plant you end up with) for suggestions that seem less attractive to voles. Most types of deodar cedar (Cedrus deodara) are hardy to zone 7, so not an option for you, though there are some types rated for colder temperatures such as 'Kashmir', 'Shalimar' and 'Polar Winter'. I'd check around at local garden centers, botanical gardens, and arboretums to see if anyone has local information as to how they do before planting them. It's tough having a borderline hardy tree that does well for several years and then is half-killed during a particularly cold winter. My inclination would be to plant native plants or ones that you are sure don't have escapist tendencies since you are on the edge woodlands, and plants such as ivy or vinca can grow into the woods, disrupting the native plants. You may find that you have already existing woodland spring wildflowers when you go into the woods in the spring. (Be aware that spring is the worst time for ticks, though they around all of the warm season, so get in the habit of doing a careful check of clothes whenever you have been out in the yard, and of your entire body at least once a day if you have been outside at all. It takes a few minutes, but I include it in my bedtime routine and haven't had an embedded tick yet, though I find them on my skin and clothes often.) Light levels: If you plant the slope with typical meadow wildflowers, you may have mixed results, depending on the amount of sun you have. Something like Rudbeckia is really a sun flower, and so may not do particularly well there. I would start taking photos at 8:00, 10, noon, 2, and 4:00. Do this at the spring solstice (mid-March, 1st day of spring), and about once a month up until the summer solstice (mid-June, 1st day of summer.) This will give you a good idea of how much sun you actually get there. If you want to try Rudbeckia, I'd go ahead and do that this spring since it will establish better with less established grass. By planting time, you may have a pretty good idea of how much sun the area gets. Water and nutrients: You might want to ID the trees along the top of the slope; depending on what you have, they may send out more or fewer shallow roots into the slope area to compete with whatever you plant. I say this because they look to me like red maples, which have fast-growing shallow roots and will compete for water and nutrients with whatever you plant. So the sooner you plant, the sooner what you plant gets established enough to be able to compete with the red maples. If you have oaks, they won't be an issue since their roots are deeper. Watch the slope and see how water levels fluctuate over the year. If it is a recently cut bank, the soil may actually be subsoil and benefit from adding organic matter to the surface, or there may be springs that will cause problems if not addressed. I'd also get a soil test done (Cornell U does them among other places) to see what will grow well in your soil. For instance, that might be a lovely place for some rhododendrons, but only if you have acid soil. Mowing: If you end up deciding to keep this meadow, it will need mowing 2-4 times a year with a brush mower to keep out woody plants. In my area those woodies include sweet fern, red maple, staghorn, sumac, white pine, black cherry, all of which like open areas for their seedlings. Seeds will blow in or be brought in by animals, and some of them will start growing, often including non-native invasives such as buckthorn, bittersweet, barberry, burning bush, and Japanese honeysuckle. In the northeast and Great Lakes area, unmowed areas will always turn into forest eventually, so you want to mow to prevent the process from getting started. In our field we time mowings to allow the ground-nesting birds' chicks to hatch undisturbed (turkeys are our most frequent ground nesters), and to allow certain plants to bloom, but for a chunk of time it is just mowed field. You can time one of your mowings for early fall just before the leaves change color, which will allow flower seeds to ripen but prevent baby trees from storing nutrients. Your landscaper may have access to a brush mower to do this for you. Regardless, the part you keep for sledding will need either regular mowed grass or the periodic Consider a mixed shrub border for the less steep part of the slope. I have one that is heavily mulched or groundcovers between plants and edged to keep out grass, and I only spend a few hours a year (perhaps an hour a month) weeding it, and it's probably about 15'x70'. It provides blooms, varied summer foliage, winter evergreens and berries, and colorful fall foliage for very little maintenance work. In the late fall or early spring I use hedge clippers to whack off the perennials and clematis to ground level. This one is full sun, but I have others in less than half day sun with a mix of shrubs and a few perennials, also edged and heavily mulched. This one is about 5 years old. Fall Spring early Winter So you have lots of options, but specific plant recommendations depend on your goals, your soil, and your sun levels.

We still need wider photos. What is the gravel to the left in the last photo? Is it over dirt or is it a French drain? Where is the neighbor’s water coming from? What is below your yard? You have to show not only your yard but also the surrounding yards that influence yours and that yours influences. I also respectfully suggest that “remains soaking wet” on a house where you just closed is a bit of a leap. I have areas of the yard that are currently soaking wet that within a few weeks won’t be, including an old farm pond area that can be mowed by summertime because it is totally dry but is currently quite literally under water with ducks paddling. So I would likely be a bit patient here. Watch how moisture changes across the course of a year or at least a summer. See how the builder’s grading works so that if he left issues, he is responsible, especially with regard to the neighbors’ outflow. Do some research about your area’s regulations about sump pump and roof drain discharge. Does it need to remain on your property? Does front vs. back yard matter? Can it be directly discharged into storm sewers? Different areas have different regulations, and you should research your municipality to find out the rules you need to comply with, not just rely on what the builder did. IME some are ethical and some cut corners. Look at how you want to use the yard and see how that changes once you live there. As a small example, in my yard a fire pit would be a waste of space because the evening mosquitoes are horrendous for most of the part of the year it would be used. So there may be aspects of the yard (neighbors, traffic noise, wildlife, sun direction and heat, etc.) that will alter your current wishes once you have been in the house a few months. IME waiting to make major outdoor changes until you actually know how your family will use this particular space is often helpful in order to spend your outdoor budget in the most effective way. Consider setting up a small seating area and a few large pots of flowers to get you through this summer. I do understand about wanting to get the yard finished (as someone who had to wait 3 years to start yard work due to issues like foundations and roofing needing replacement), but I do think that in this case, patience might be the better choice.

If you want level play areas you have to build a retaining wall and fill in behind it. Your yard does not slope much and the retaining wall would probably not be more than 12" high. Fill dirt can take several years to settle, so plan on having concrete piers in the ground for the support poles to sit on. The retaining wall could be fairly wide as you have to make the level area not just large enough for the swing support poles, but also allow for the arc of the swing outside the support posts. A swing/slide could go in a shadier area than the pool. You should put the toddler pool on the patio, and take your child to a public pool as he gets older. All the issues of creating a level area and allowing fill dirt to settle are much more important for an above ground pool, because a U.S. gallon of water weighs 8.3lbs. A 12' round pool that is 4' deep contains 2,975 gallons and weighs about 24,692 lbs. If this small pool collapses the resultant flash flood would damage your yard and the drainage easement downstream.

Add the wall if you are going to, weed well, and then add roughly textured mulch that will knit together and help retain soil and moisture while you get a plan in place. You want to avoid getting a good crop of weeds growing, and you want to retain the trees that are there now. Do not use landscape fabric which will lead to a host of issues down the line.