I could see a tree and solid groundcover. But not shrubs. Especially shrubs that potentially block views and stand a chance of being neglected -- pruning, watering, driven on, walked on, etc. The right groundcover stands a good chance of being self-healing. A large tree that produces blazing fall color could be awesome.

"The plows currently dump snow there, but that will have to be minimized in the future." Who can mandate and enforce that the plow drivers won't dump snow there? I see this as the first and most major hurdle for this as a planted area. Will some snow (and therefore salt) be plowed onto the edge of the island as the road is cleared, I assume? Will there be curbing or something to tell the plow drivers where the edge of the island is?

I would hate for you to find that since the plows are already using this as a snow dump area, that any plans and plantings you do can be damaged, and so until some determination is made of exactly what part of the island is safe to plant, I don't see how you can make plans.

I agree with Yardvaark that you want to limit any plantings to a combination that only includes plants that will either be below or above good sight lines for driving. One plant that is low enough growing to use as ground cover and is somewhat tolerant of salt and poor soil is Heather/Calluna.

@Yardvaark funny you say that about fall color...I've been picturing a Tupelo or October Glory maple, but I didn't mention it to not influence suggestions. I will check out salt tolerance. Also was thinking of Liriodendrum for quick growing. Groundcover good idea.

@NHBabs The builder plans on creating an asphalt berm edge similar to the ones on the sidewalks nearby. The plow crew claims responsibility for damage them. One of the drivers does a great job not hitting them. The others hit them all the time. They repair them in the spring (but it makes for a patchy mess over time). I suspect they will plow snow over the berm similar to what they do now with sidewalks -- a few feet or so. I had been thinking that the more plants are present, the more they will stay away and less snow will be pushed onto the island. We don't have much control now with the builder still present, but probably can mandate more later on. They should be complete and gone by the end of this year.

I always thought heather was borderline hardy. Does it need cutting down periodically? I think of it more in context as a perennial than a ground cover (although those terms are obviously quite interchangeable).

Maybe this is an good site for euyonmous fortunei coloratus. I had that on a hillside for 10-15 years at my former house and it was quite nice until it became a monster and I had to rip it all out. It was heading for the next town! I guess it could not escape the island.

I'll go google salt tolerant groundcover.

Thanks for your inputs!

Before planting a tree it would be good to add some topsoil to slightly crown the island in order to give it a fuller looking appearance. If it's pure flat it will tend to look sunken.

Personally, I wouldn't make "quick growing" a factor. Most any tree will grow quickly enough to please the neighborhood. The tree's longevity, beauty and overall good habits will be much more important not far down the road. Among the others, consider a male clone Ginkgo biloba if you can find it, as it has many good qualities, not the least of which is that when the fall color show is over, the leaves drop suddenly which helps the clean-up not to drag on ... good for a street tree.

A good groundcover for an area like this would be able to repair itself when damaged and, more or less, wouldn't be prone to damage. Anything that is shrub like -- forms twigs and stems -- is going to be breakable. I would consider something durable like Virginia creeper. It makes an excellent low care groundcover but is often overlooked because, like any vine, it can be rambunctious, and therefore feared in someone's private, manicured setting. Here, that quality is its asset. It would only need to be trimmed at the edge (which is a quick and easy chore) and clipped from climbing the tree once per year (probably during the winter so it's leaves will have already fallen off.) One does not even need to remove the clipped vine as it will fall off on its own accord. In the winter only an undamagable network of vines remain, hugging the ground. There is room for all the snow one wishes to pile on them. V.C takes sun or shade so would have no trouble adapting to the changing light conditions that occur as a large tree grows. It could be found for free since it's pretty much everywhere and would be easy to start by anyone who has knowledge of plant propagation.

@Yardvaark You make a good case for VC. All those points are true, but it still is scary. And it more or less forces a single species planting. I would like to see some layering and/or co-mingling for more interest. For the 3-4 months when there is possibly no snow cover (Nov,Dec,Mar,Apr), it would be nice to have a bit more substance.

Rhus lo-gro? stephanandra incise? (there's those stems again...) maybe some herbaceous plants closer to the edges...

Love ginkgo. I did a quick google image search and see mostly a low-ish canopy. Is that a concern? However, the driving volume around the cul-de-sac is incredibly minimal. A UPS truck may turnaround once a week... that sort of thing. It's hard to imagine driving sight lines would matter, but until it's in place, hard to judge. It's something to consider definitely.

Is ginkgo considered a "street" tree? i.e. salt tolerant, tough, drought-resistant

Any hardscaping ideas or embellishments for the future after the builder is gone and the community might want to "play" here a bit? bird bath, bird feeders, walkways, benches ... ???

I don't think I would want either the Rhus or the Stephanandra, and I really like the Virginia creeper idea. I think you are right about the heather's woody stems not being good for the ground cover, but the individual plants will reach out to make a good ground cover sort of the way folks use junipers, only more interesting. ;>)

For trees, I like both the Ginkgo or the tupelo. Ginkgo have the reputation of being good street trees, and I know that tupelos grow within a few feet of the Lamprey River in S. NH in an area where the tides are active, so they are salt tolerant.

For other interest, how about large seasonal pots with annuals in the growing season, and evergreens and berries in the winter. Until the tree achieves some size, I think a bench would look out of place, but when larger, a bench might be nice in its shade; it depends if this is likely to be a realistic destination for neighbors to come to hang out.

Hmmm, WendyB ... I think what you're calling "more interest" I'm calling more junkiness. It sounds like there's a thrust to make this area more back-yardish-like. Whatever floats your boat. But for my taste, it would be straight-up simple. Just a good tree and a good groundcover. BTW, I've seen V.C. used this way before and it works out quite well. It was actually in a private back yard in a fairly small (12') island. The people who owned it were not yard-working kind of people (which I can't understand!) and they like the V.C. because it was easy to maintain, free and unfailing in its Old Faithful-like performance. I thought it was very attractive itself.

We live in a world where one could drive down most any street and see unending low-limbed trees -- trees that obscure houses -- in people's front yards. This is not because everyone decided that this looks great. Most owners have a fair amount of fear of what will happen if they cut off a limb. Sometimes a paralyzing amount. They have a fair amount of "I'm too tired to do yardwork. Let's let that go until next year" ... which sometime never shows up and then what do you know, it's time to sell the house and move. It will turn into someone else's problem. So if one googles images of Ginkgo and sees lots of low limbed trees, it's not the trees fault. Any tree can be limbed up. It just needs sometime to take an interest in it.

I am glad there will be a curb. To mark the edges to keep the plow out, one can get thin fiberglass poles with reflective tape on top. Though not beautiful, a few of those put out before the ground freezes may save you work redoing in the spring.

I am following this with interest while trying to learn the basics of good design. If a tree is planted (on a raised berm) should it be smack dab in the middle of the circle? Or off-set?