One of the most obliging of all garden plants, and maybe the best perennial for the early fall garden, is the Japanese anemone.
Once you have it, you have it. There is no question of replacing it every few years. It spreads moderately but is not invasive, and so far as I have seen it is not bothered by mildew, viruses or bugs.
From a tuft of basal leaves it sends up flower stalks three or four feet high with many buds that open over a period of several weeks. The individual flowers are about the size of silver dollars, either white or rose pink, with conspicuous yellow stamens at the center. There are also semidouble forms.
I like the plain single white one best, but the rose-colored ones are equally tough. To my dismay, the hound chose a pink Japanese anemone to gain purchase for her hind paws while drinking out of a raised pool this summer. I had fenced off her usual standing place to protect a new tree peony, leaving several feet between it and the anemone. The hound, instead of using that space, moved a bit farther to stand on the anemone, a thing I discovered after an absence of several weeks. Even so, the poor pink anemone is blooming, its stems almost horizontal, a thing I mention to suggest the resistance of the plant to various outrages.
One year, wishing to treat this plant well, I gave it a mulch of manure and never let it get dry through the summer. Its stems were about five feet high that year, but they leaned about more than usual. I resolved not to treat it so well after that. Ordinarily, if it is not coddled, its stems are strong enough not to need staking.
On the other hand, one good late-summer storm of near-hurricane force will of course knock the stems over, so it really is better to set out slender stakes in August, not that I ever do.
In the bishop's garden of Washington Cathedral (Episcopal) I have often admired the white anemone blooming amid fat old clumps of box, one of the happiest associations imaginable.
The anemone also looks good back of late-flowering hostas. But the hostas are too dense for the anemones to compete with, so they should be separated by three feet or so, but when they bloom together (their bloom overlaps, though the hostas finish before the anemones) the two kinds of flowers almost touch. One year they both bloomed right together with a background of water sprinkled with blue and pink water lilies.
At Dumbarton Oaks in Georgetown, the most elaborate garden open to the public in the capital, there is a narrow border of the white anemones against a masonry wall. When I first noticed this one year in the spring, I thought now that is a mistake, because the anemones will lean toward the light and flop all over the walkway. But in the fall the anemones stood straight up, the result of careful tying in of the stems. It is not really that much work to tie them back to the wall and the result is well worth it, but of course it is one more task for the gardener.
If you had a whole bed of these anemones you would have flowers from mid-August to mid-October, but you should not expect so long a display from any single plant.
Another splendid creature for late summer and fall is the creeping plumbago (Ceratostigma plumbaginoides), which bears electric blue flowers the size of a nickel from late summer till mid-November. It is used with fine effect in the bishop's garden, and looks good between the old box bushes and the pavements.
It will grow in heavy dry shade -- it will grow in dry places if it's watered, and you may say well, if you have to water it, why say it grows in dry shade? In fact, most flowers will not grow in dry shade no matter how much you water.
I have a scrap of this plant on a dry bank beneath a large pin oak, and what rain gets through is seized by the rather large azaleas that struggle along. They do not really struggle so much, as I never let them get dry and have to water them off and on through the summer, while other azaleas of the same type that are not on the bank, but on a flat space, do not get watered at all.
Anyhow, the little plumbago, which is utterly overwhelmed by the azaleas and the various other oddments, still manages to bloom. You will see its gentian-blue flowers sparsely scattered about where it has found a tiny patch of light here and there.
The plumbago is happy in full sun, but will bear as much shade as a lily of the valley. The more sun the more beautiful its leaves in the fall, when they turn rich tones of crimson. But however obliging this plant is, it does not smother weeds. Do not plant it expecting it to form a weed-proof carpet. The only plant I have grown that really does not allow weeds to come through (and which is handsome enough to use in a garden) is the little tribe of epimediums, or barrenworts.
If I had a patch of land beneath old oaks and maples, and did not want grass (which is a royal pain on shade and dry places) I would consider patches of the plumbago, barrenwort, lungwort, purple bugleweed and periwinkle, making each patch eight feet wide, say, and let them fight it out. Beneath that cover I would plant such bulbs as might have a chance of coming up through it in the spring. Nothing could be expected to rise through the barrenwort, but the other plants are not so dense, and such daffodils as 'February Gold' would be good for 15 years or so. So would the Spanish squills or wood hyacinths (Scilla campanulata). The delicate wild crocuses are not so reliable and neither is the marvelous little blue star-flower, Ipheion uniflora, which takes drought and shade, but not dense plant cover over it.