Check out Tropical Bamboo Nursery. They have many varieties suitable for zones 9 and 10. They only grow clumpers, not the invasive runners. If possible, I highly recommend visiting them to see their display, and oh and ah over the mature Boos. It is a lovely place! I have Dwarf Buddha Belly (7), and a variegated dwarf, that only get to 12'-15' tall. They can be trimmed to make interesting lower culm displays, or left full all the way up. I have 4 other, taller varieties too, but it is raining too hard for me to go read the tags(G). Asian Yellow is really pretty, as is the blue one, Angel Mist. Seeing the different types all in one setting, makes a huge impact. I LOVE visiting there! Boos grow very quickly, so be careful about getting a type too tall for the area you have. Lisa Here is a link that might be useful: Tropical Bamboo

Amongst the best palms for the PNW would be the Windmill Palm, Trachycarpus fortunei, which is the palm in the pool photo. Other species of this genus to look for would include the more refined leaf form of T. wagneriana or T. takil. A smaller growing fan palm that is also perfectly hardy is the Mediterranean Fan Palm, Chamaerops humilis. There is also a lovely silver leafed version, C. humilis var cerifera. You might also be interested to try growing one of the hardier feather palms, such as Butia capitata, the Pindo Palm. Other subtropical plants that are often used in PNW gardens for a tropical effect would include the various Phormium hybrids, Cordyline australis hybrids and cultivars, and Beschorneria yuccoides. The silvery foliage of Astelias, which much resemble Phormiums in habit, are also quite hardy for Seattle, and would include the larger growing Astelia chathamica 'Silver Spear', and others such as A. nervosa 'Red Gem' or similar. Fatsia japonica is always a reliable tropical looking foliage plant. Usually not quite hardy as year round perennials in all but the mildest PNW locations, but great as temperennials, the Abutilons of all colors are great filler plants. Bergenia was already mentioned, but this is a great foliage plant that also blooms in late winter, and is fully hardy, coming from Russia. Winter deciduous subtropicals such as the various Hedychiums are also great, such as H. gardnerianum, H. flavescens, H. greenei. Cautleya spicata is also quite nice, and is quite colorful with summer blooms of red and yellow, and will even bloom in a fair amount of shade. My favorite Canna varieties for tropical flair would have to include the very tall growing C. ehemannii, which can get 10 feet tall, and has smaller rose red pendant flowers that cleanly drop off when done blooming. If you want dramatic foliage that is the equal of a Gunnera, you might also consider planting the Rice Paper Plant, Tetrapanax papyriferus, but this will probably be killed back to the roots in winter in most PNW locations. Melianthus major is another great foliage plant, but will often be killed back to the roots outside USDA zone 9a conditions. As to Acanthus, you should also look for the attractive A. spinosus, which has distinctive looking leaves. Acanthus does perfectly well in full sun in more coastal locations that don't get the baking summer heat of interior Oregon, but in its native Mediterranean habitats it will also quite willingly grow in full sun locations as well. In dry summer locations, it will go summer deciduous, and come back into growth with fall rains. In irrigated gardens, the yellowing, heat damaged foliage can simply be pruned off, and it will often push new foliage immediately if watered and fertilized, or can be allowed to wait until it cools off and starts raining again.

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.

These sunpatients grew fast and quick, the durantas in this spot keep getting drowned when it rains they haven't grown much. I'm thankful they haven't died yet. I will probably give these another month before attempting to shape them but everything is filling in.