The planting districts in the northwest are very sharply defined. They include (I) the West Slope; that is, between the coast and the mountains, or west of the Cascade Range, and (2) eastern and central Oregon and eastern Washington; that is, all of the district sometimes spoken of as the Inland Empire where conditions show very marked changes. The following lists of plants apply only to (1), this being all of the territory west of the Cascade Range exclusive of the mountain slopes and known as the Oregon and Washington Coastal Plain. No effort has been made to compile lists for (2) known as the Inland Empire. There the rainfall is very much lighter, more snow falls in the winter, and much hotter days prevail in the summer, although the nights are always cool.
There is also another separate district spoken of as southern Oregon. The elevation here is from one thousand to eighteen hundred feet, with conditions much drier than through the Willamette Valley and all through western Washington. The factor in southern Oregon which appears to control plant growth is water, and if one has plenty of that coupled with a reasonable amount of good soil, normal growth can be developed.
Even in western Washington and Oregon the days are fairly warm and the nights in most cases are cool. This condition makes itself felt very much in the growth of annual vines, because they do not like the cool nights.
This entire western country appears to be the natural home for coniferous evergreens and for most of the broad-leaved evergreens. They do wonderfully well all through the northwest, west of the mountains. Portland has become known as the Rose City. It has found one particular thing, however, that is not proving a success. The camellia has been largely planted and is generally proving more or less disappointing. The mountain laurel should probably be placed in the same class. It does not appear to do well and yet rhododendrons planted under exactly the same conditions thrive.
Plate LII. There are those who much prefer to develop their formal flower garden picture entirely by the use of annuals. This garden which is not for a source of cut flowers is filled with heliotrope, yellow tulip-poppy, snapdragon, pentstemon, annual carnation, candytuft, and others not recognizable from this picture. (See chapter XXXII (Annuals))
Plate LIII. An informal planting of Scotch pines and Mugho pines may be accented by the use of a few specimens of lilies to brighten the landscape picture as well as to serve as a background for the flowering effect of the lilies, (See page 256, group XXXIII-F-b)