A peculiar situation exists in the relative hardiness of trees and shrubs for seaside exposures. Plants which are entirely hardy on exposed river front and fresh water locations are apt not to thrive at the seaside, especially along the Maine Coast and the more exposed points of New England. Where the climatic conditions of the winter are not extremely severe, as on Long Island and the points farther south, most of the hardy trees and shrubs are well adapted. There are locations on the exposed frontages of the Great Lakes where conditions are equally as severe as are conditions on the east coast of the northeastern United States. The salt air condition and the salt spray during the winter months does not become a factor, however, in lake front exposures.
Perhaps the most severe conditions of seaside exposure in the country are along the shores of Penobscot Bay and the Maine Coast. In all ornamental plantings in these locations it has been a question of experimenting to determine the trees and shrubs to be used to withstand the extreme and severe conditions of the winter months. The growing season is short. Therefore trees and shrubs which require a longer ripening period in the mid-summer and early fall months are subject to considerable winter-killing because of the immature condition of the wood when freezing weather begins. This same factor also deprives the early spring-flowering shrubs of the wood which produces flowers on buds formed the year before. The deciduous trees which are hardy along the coast of Maine are those which are indigenous to that section such as beeches, red oaks, willows, and red maples. None of the more refined types of evergreens, with the exception of the red cedar and the prostrate juniper, have proved hardy in these locations. The American arborvitae in many instances is hardy, and in others has not proved hardy. The white cypress is rarely seen. A number of shrubs which are included in this list have proved themselves extremely hardy and able to develop into mature types which make excellent specimens and good mass plantings. The location considered in this discussion is along the northeast shore, where the exposure is the most severe. In the inland sections, removed from the severe exposure of the salt water, and protected by buildings and woodland developments, a large part of the list of generally hardy shrubs used throughout New England can be planted with safety. All of the material in this group, however, has been under observation for a number of years and has proven itself thoroughly hardy.
In going farther south along the less-exposed New England shores we find a group of trees and shrubs which are fully hardy, but which do not develop at their best along the severe exposures of the Maine Coast. All of the material shown in the first list is fully hardy along the New England Coast and the less-exposed shore locations. There are many other shrubs which might prove hardy. Under the author's observation many types of this material have been used at one time or another. Sources of responsible information have been further consulted and many plants of questionable hardiness, which might otherwise have been included in these groups, have been for the present omitted.