THE ONLY good thing about the Rayburn House Office Building that I can think of is its magnificent retaining wall of fitted boulders, handsomely furnished with climbing hydrangeas and ivies. gether, and I resent the comment (sometimes heard) that walls are better without vines. As far as I know, there is not a single wall in this city of sufficient architectural interest or delicacy that a few vines would not improve it, and most walls fairly cry out for God's greenery to cover their grosser aspects.
Ivy is not the answer. It is beautiful, but it will grow anywhere, and need not be given so treasured and valued a site as a house wall.
Let us start with a wall facing north:
In very sheltered places (a virtual courtyard flanked with wings or walls) I would try a creeping fig, usually grown in greenhouses. Its tight flat skin of greenery over a wall is delightful, but here we should not expect it to grow more than four or five feet, and should expect it to die back every winter. I mention it only because sometimes you see just such a sheltered spot, with nothing but a coarse forsythia bush against the wall.
More useful for the average gardener are the many sorts of large-flowered clematis. The huge white 'Henryi' is vigorous and reliable, and its flowers as large as saucers are striking in the shadows of a north-facing wall. Many other clematis are equally suitable, though not the red ones, which seem to prefer a bit more sun.
The winter jasmine (Jasminum nudiflorum) is a perfect choice for a north wall. Just here let me say I know it does no good at all to try to be specific. Recently I mentioned the Carolina jasmine (Gelsemium sempervirens), which I clearly identified as a vine with fragrant flowers in, April, and marked its difference from true jasmines. This was the signal for every careless reader in 37 counties to write in complaining that my description of the Carolina jasmine did not accord with their impressions of the winter jasmine.
Since they are totally different plants, that was not surprising.
The winter jasmine is a shrub, like a green-stemmed forsythia, only with much more refined, small tubular or star-shaped flowers strung all along its arching or weeping branches. It is ideal, by the way, for planting atop shady walls facing north.
Many Washington houses have stairs down to the basement on the north side of the house, and this shrubby jasmine is admirable when it tumbles down the retaining wall along the steps, since it blooms off and on in mild spells from late January to spring.
The old birthword (Aristolochia durior) has round-oval heart-shaped leaves that lie down over each other like shingles, and makes a tremendously opaque screen. Gloomy, some say. It will grow on a north wall or any other. The leaves are as large as a hand.
I do not think the Virginia creeper (Parthenocissus quinquefolia) is good on a wall unless it is a very large one with a trellis fixed against it -- a very large trellis -- and even then it fails to show itself as well as it does on an old tree. But its relatives, the Boston ivies, cling tight without support. A dismal use of this vine is to be seen in the garden of Blair House, covering vast monotonous brick walls with vast monotonous green.
On any wall the Boston ivy will blanket every detail, and will grow over windows and under shingles. For all that, it can be effective in those rare cases in which the gardener has energy enough to keep it trained to a limited part of the wall.
Very different in habit and effect is the dwarfish variety 'Lowii,' which is a perfectly reasonable choice to trail up the wall of a masonry planter or raised pool, or to play upward for a few feet, very delicately, around a doorway.
North walls are peculiarly unsuitable for trumpet vines, morning glories, cypress vines, moon vines, all of which like a great deal of sun.
A grape vine can be handsome on a north wall, with no thought given to fruit production, but of course such a vine must have stout wires fixed to the masonry for it to climb on, and much thought should be given to companion plants and wall textures.
A grape on a brick wall facing north, associated with a hydrangea with white-variegated leaves and a few fat clumps of Hosta subcordata (the one that blooms in August or September) and some lily turf can be handsome. But it will not look good if the grape is allowed to smother the wall, so judgment must be used in the amount of space it is given.
Many shrubs can be treated as if they were vines, that is, grown smack against a wall. Among beautiful subjects are Pieris japonica and P. forrestii (a bit on the tender side); Photinia serrulata and P. fraserii; Mahonia aquifolium, M. bealii and M. japonica, and Nandina domestica. All of these have evergreen leaves of the highest beauty, and all make bushes of considerable distinction.
So, of course, do camellias.