THE VERY smallest garden should have blazing sunlight, complete shade, color and water. It should also have happy proportions and should be enclosed. It should have masonry and wood. It should be fully private.
If these things are lacking, it will not give much pleasure to the semi-civilized gardener, whose first and cardinal task is to tend to any of these requirements that happen to be lacking.
In crowded towns one is lucky to have a garden at all, even if it's no larger than a kitchen, and sometimes the garden lies to the north of the dwelling and gets little sun. Or, again, there may be old trees leaning over and shading the garden almost completely.
The first thing, then, is to get rid of enough trees to allow some sunlight in, where that is possible, and it usually is possible provided the gardener maintains a cheerful approach and steely determination.
Suppose the garden in question is about 20-by-25 feet. It may be surrounded by buildings (more troublesome to chop down than trees) but even in this case it is possible to make the most of what sunlight there is.
In particular, it is possible to refrain from planting some dumb tree that will diminish such sunlight as enters.
Suppose the garden lies to the north, the sunless side of the house. The farther away you get from the house, the more sun there is, so it is important not to plant anything on the east, west, or south that would cast shade. Keep the far end of the garden sunny. There will be plenty of sun, even on the north side of the house, once you get 10 feet away from the wall.
Let the house side of the north-facing garden be given over to a shady place for sitting, since the lack of sun is a built-in handicap anyway. The wall of the house may be ugly, it usually is, and may be planted with a grapevine grown on a stout trellis attached to the wall, or variegated ivy or even the self-clinging Boston ivy or ampelopsis.
Even better, sometimes, is a shrub that requires little sunlight, such as a camellia or a hydrangea (the variegated blue lacecap one called 'Variegated Mariesii' is a good choice) or a photinia or mahonia.
A word should be said about climbers on the wall that faces north. Unless ivy or ampelopsis is chosen, there will have to be a support for the vine. Do not buy trellises, since the ones offered for sale are usually shoddy in workmanship and insubstantial in construction. Instead, take 1-by-2 inch lumber of good quality (clear pine, oak, redwood, etc.) and lay them to form squares 10 or 12 inches; screw them together or nail them, then paint the wood with one coat of exterior primer paint and two coats of black exterior paint.
Attaching this trellis to the wall is rather a pain. If drilling into the wall and bolting the lattice in place seems too much of a project, then use 4-by-4 posts set into the earth right against the wall, and nail the trellis to the posts.
There is no point thinking you will be happy with some flimsy support of wires or nylon strings.
Once it is in place, it will be there for years. If a flowering vine for the north wall is needed, you might have a clematis such as 'Nelly Moser' or a honeysuckle such as Lonicera heckrottii with carmine-rose little trumpets, yellow inside the throat. It is fragrant only at night, but has the exceptional merit of blooming fairly steadily from April to November.
Anything planted against a north wall, or any other wall, demands generous treatment. Excavate several cubic feet and replace the earth with a good mixture of garden loam with two or three bushels of peat moss, leaf mould or compost thoroughly dug in. Treat the vine or shrub as you would treat a treasured potted plant, when preparing its planting station.
There may be only a kitchen door opening to the garden. If so, dignify it by covering it with a small arbor, four posts and a roof of substantial lattice, say. Often there is a step down from the kitchen door. If so, and if it is concrete and looks like a cracked sidewalk, change its surface by covering it with brick or squares of stone or wood decking. Grow a vine over this arbor.
The thing to beware of is flimsy material. Use treated timber, sturdy posts, and paint it all black. You may ask, can it be painted violet or orange? Of course. Paint it black.
You may not like sitting against this wall on the dirt. Make or buy four small chairs or benches and a small table. Pave the dirt with brick. Set the brick on the dirt, you do not need a sand base or anything else and you do not need mortar. If you still feel a bit exposed, build a small summer house with vines on it, right against the wall. This may be as small as eight feet square, the sides filled in with lattice for vines.
Let the pavement, whether brick or stone or concrete (if concrete, take trouble with it, there is no need for it to look as cruddy as concrete pavement usually looks; you can cast concrete paving stones 18-by-24 inches, giving them a sandy surface finish, slightly colored with yellow iron oxide), continue past the sitting area of the house wall out into the garden. Remember, we are speaking of a garden only 20-by-25 feet. Before you reach the far wall, which of course is not very far, and which is the sunniest spot, you might have your chief ornament. This should be a pool for waterlilies and fish.
If, however, you just do not want a pool, you could give this choice site to a bed of roses or lilies or what you will. Or you might continue all the way to the wall, allowing room for a piece of sculpture or a good-looking stone or metal vase filled with flowers. Such an ornament might be given a raised platform to emphasize its importance.
Or you might espalier apples against the wall, or give this sunny wall to a cherished climbing rose.
The short side borders to the east and west could be planted with whatever you consider choice things, maybe azaleas, nandinas and hostas, remembering there will not be much sun.
I am certain that for me the greatest pleasure would come from the lily pool against the sunny wall, with a grapevine clothing the wall, and since the space between the house wall and the far wall is so brief, I personally would have only the grapes, perhaps with a couple of posts and chains, so that both walls and the paved space between them were garlanded with the vines.
The main thing is for the paving to be sensible and uniform. Use brick or whatever, and refrain from seeing how many designs you can work into it and how many materials you can use. Stick to one and keep it simple. Put your faith in climbers and sturdy trellises and a tank of water in the sunniest spot.
This is, I am aware, not a very novel sort of garden, having been discovered roughly 4,000 years ago in Egypt, but for a tiny garden in Washington, it is as nearly perfect as you could wish. Do not waste the small and priceless space on fripperies that give no pleasure. Do not junk it up with "ornaments" that do not ornament anything. Do not make it restless with a bunch of dumb geraniums and impatiens and marigolds and other clutter. It is too valuable for child's play. Keep the pavement generous, limit the plants to the sides, and do not be afraid of hollies, photinias and nandinas though they are not much in flower. Do not be afraid of plants whose leaves are better than their blooms, such as hostas, ferns, ligularias, bergenias. If you need flowers, get a large handsome tub (a half-barrel is not too bad) and fill it in season with what you will. Among the shrubs at the side you might have some lilies for July, some daffodils and tulips for spring, and one really big pot full of chrysanthemums for fall. If you decide on sculpture, use one and one only, and do not use anything you do not consider good enough to put in a museum. If what you want costs a thousand bucks and you don't have it, then do without. It is very simple.
Your problem, after all, is not how to fill the space up, but how to keep it uncluttered and how to make it beautiful. No great novelty is called for here, or in any other garden. What is called for is proportion, texture, light and shade, sturdiness, clean materials and (God help us all) more restraint than you ever knew you had.