I wonder if you asked the head gardener/groundsman at a botanical garden, if he/she might know of a nursery that will carry the size you are looking for? They sometimes have to fill in empty places, and also may have a 'stash' of large container plants in their back-up nursery. I wonder also, if one might plant a rapid-growing "temporary" tree to fill the light-blocking needs and act as a nursery-tree for slower growing natives? The 'temp' could be cut down after the native had reached a suitable height. Does that sound workable? Here is a link that might be useful: CA Botanical Gardens

I'd recommend summersweet clethra. It comes in white or pink, grows to about 5 or 6 feet and has fragrant flowers from about mid July to mid August. This plant has a very clean appearance even without pruning

Hi janeymax. You're not getting a lot of responses here, typical of this site I'm afraid, and it's also likely that not too many folk have tried pleaching Aussie native plants - and I haven't either. However, might I suggest a non-native which just might work for you. There is a pittosporum - a pretty hardy family - that is a variegated form that has quite an attractive silvery shade of leaf. It grows (at least in my experience) to around 2.5 to 3 metres. Shouldn't be difficult to obtain from any largish nursery. Good luck B.

Do all the plants need to be salt tolerant or only some? Does the tolerance include foliage and airborne spray, or roots and salty runoff, or both? Plants don’t make much of a difference to sound levels; only something solid like a wall or solid fence can do that. Plants can provide visual screening, however, and if planted on a berm, the berm can provide some sound blocking or reflection. Most of what grows that is native in zone 4 isn’t evergreen except for conifers, and not many of them are salt tolerant IME. You could also try growing from cuttings if other folks you know would let you, although it wouldn’t have genetic diversity unless you took cuttings from different shrubs and trees within species. Just so you know, Rosa rugosa isn’t native or evergreen, though it has naturalized over a fair amount of the Northeast. There are native roses such as R. palustris AKA swamp rose and R. virginiana. For evergreens, balsam fir as it grows on my property is relatively narrow, but as with most of these plants, I don’t know about salt tolerance. Check out junipers as another hardy needled evergreen that may have some salt tolerance. I can grow Rhododendron maximum, but it does get winter foliage damage in sun. My mountain laurel AKA Kalmia latifolia Seem to do better with keeping their winter foliage looking nice, but are mostly in at least part shade, so that might be the explanation. I don’t think either is salt tolerant. Yew tend to be eaten by deer if they are an issue for your site, and often Thuja are eaten into lollipops as well, with all foliage missing as high as the deer can reach, so you may want to set up protection for them this fall, either netting on posts or a webbing of posts and high test fishing line which they have difficulty seeing. For deciduous plants, look into the native Viburnums, some of which should be hardy enough for you, but I don’t know about salt tolerance. Physocarpus AKA ninebark isn’t evergreen, but it is densely twiggy and so provides fairly good visual screening and is a US native. Hydrangea arborescens is native, but in my garden doesn’t get taller than 4’-5’ and prefers shade in the afternoon. I have seen Amelanchier AKA shadblow or serviceberry growing in the median strip of the interstate, so it must be at least slightly salt tolerant. There are several deciduous dogwood shrubs and Ilex verticillata AKA winterberry holly that have winter interest. If you are looking for an inexpensive source of seedlings so you don’t have to grow your own, check out the NH state Nursery. Order early next season (check in January) since I think that they may be done shipping for this year and they often sell out of popular plants. Many, though not all, are native plants.