A drizzly chilly day the end of August was just right for visiting the National Arboretum, where, as usual, I found plants new to me and others used in ways I had not thought of.

The herb and rose garden is now looking good. There are several tea roses in a bed, and I have often wondered about one labeled 'Adam,' which is a typical white tea with fawn center.

It is supposed to be the first, or one of the first, tea roses dating from early in the last century, but it looks like a rose of the 1880s rather than the blowsy early tea rose varieties like 'Bon Silene' or 'Safrano.'

The tea roses are scarcely to be found in gardens now, even in moderately mild climates, as they have been replaced by hybrid teas and floribundas with stronger colors, neater bushes, and with flowers of heavier texture and firmer stems.

Still, the teas of the last century are usually free of blackspot and mildew. The arboretum teas are sprayed, but I doubt that is necessary. I once grew a collection of teas and can say they do not care for pumpkin vines to overwhelm them, but the answer to that far-from-universal problem is not to grow pumpkins near them or, if you do, not to go on vacations.

In Washington the teas will need attention in the winter. A successful grower in Delaware tells me the trick is shelter from the wind. But I would also try a four-inch mulch of wood chips and a good many evergreen branches (cedar, spruce, cut honeysuckle or whatever is handy) among the plants, and I would not prune them till early April.

As gardeners soon discover, even in Zone 7, even hybrid teas (which are hardier than most teas) are killed outright by occasional cold and are vulnerable to sharp freezes following a mild February.

A quite famous tea rose I used to grow and never liked is to be seen at the arboretum -- 'Safrano,' a white rose of few petals in a somewhat shapeless arrangement. Its buds are bronze-orange and beautiful, but they open quickly and fade by noon in our sun. A primrose or lemony sport of this is 'Isabella Sprunt,' which also fades. Both these roses have rich bronzy red new leaves.

One of the most tender teas is the white 'Niphetos,' also seen at the arboretum and seemingly doing well, though it was always thought of as a greenhouse variety. Two better choices for the gardener are 'Maman Cochet' and 'Duchesse de Brabant,' fragrant pinks and as hardy as hybrid teas. An especially good tea, from early in this century, is 'Lady Hillingdon,' which opens rich bronze-yellow and fades, but not as badly as 'Safrano.' As teas go, it is quite hardy, and like the others it has healthy foliage. All these teas at the arboretum bloom freely, far more freely than most hybrid teas, and while I do not urge anybody to try them, I find them more beautiful than most hybrid teas. They are said to grow better on their own roots, that is, grown from cuttings. Gardeners of a slightly adventurous turn of mind can manage them with protection as far north as Zone 6, and fanatical gardeners even farther north could grow them in large pots, or could dig them up in the fall, shelter them in a wooden box (the space between plants insulated with dry leaves) to plant them out again in spring.

The great arbor in this part of the arboretum is now covered solid and somewhat monotonously with grapevines. Eventually it will be noticed they are ugly when viewed from beneath, and it is already apparent that because of the great height of the arbor and the consequent near impossibility of trimming, nothing else can be accommodated. It is a good lesson to all gardeners that grapes need to be severely controlled to show at their best, and I speak with some feeling as one who has suffered bitterly from their vigor. In a matter of days a grape can leap out and strangle even a trumpet vine, to say nothing of climbing roses.

Beneath the arbor on its excellent broad pavement are occasional pots that might inspire home gardeners. Especially handsome now is a big pot of the scarlet Bouvardia ternata, which is somewhat like a lantana only with longer tubes to the narrower flowers. In the light shade of the grapes it is stunning.

It never would have occurred to me to grow Buddleia crispa (which is a bit on the tender side, and needs a somewhat sandy soil and the shelter of a south-facing wall if grown outside) in a pot, but it makes handsome pot plants indeed. So does the dwarf pomegranate when it has wrist-thick stems and bears its scarlet flowers and interesting small fruit together in August.

A good houseplant, seen here in a pot beneath the grapes, is Jasminum polyanthum, a tender jasmine from China. It flourishes on the Mediterranean coast but is too tender for our winters. Its flowers of usual jasmine trumpet shape are pinkish outside and powerfully fragrant in late winter indoors. Yet another fine plant for pots or tubs in houses that are cold in winter (or in a barely heated sun room or porch) is the intensely perfumed sweet olive, Osmanthus fragrans. I have repeatedly tried it outdoors in Zone 7, and, while it may pull through a winter or two, it dies at last and is therefore more safely given a tub and cold-greenhouse conditions.

The herb garden now boasts an astounding collection of plants and well deserves any gardener's attention. It is particularly handy for seeing herbs of no ornamental value (like woad) and plants unlikely to gain a place in the garden, though quite handsome at some time of the year (like fuller's teasel).

Two plants of merit for the small sunny garden are Tulbhagia violacea, the society garlic, and Allium tuberosum, the Chinese chives. The first has striking tufts of leaves, little fountains of green with white stripes and charming rosy violet flowers on stems slightly more than knee high. The second has masses of small white onion flowers 20 to 24 inches high, as profusely borne as those of ordinary (and beautiful) common chives.

A plant new to me is used here and there in great pots as a creeping cover with other pot flowers, Evolvulus. It has dime-sized blooms slightly darker than sky-blue, and would be a reasonable substitute for Convolvulus maritima, a small blue morning glory that for some reason seems to be impossible to find. You understand that neither of these is a morning glory in the usual sense; they hug the ground and are not invasive, far from it.

Once I got together a group of late-flowering day lilies on the theory that they'd be welcome in late August and thereafter, but most of them bloomed in July only a few days after the main flush of day lily bloom (which for me is July 4).

The arboretum has one that is in full bloom the second half of August, labeled Hemerocallis altissima, which it got from the Arnold Arboretum at Boston. It is identical with one I bought years ago from Scheeper's in New York, called 'Autumn Minaret.' The flower stems are six feet high but do not require staking. One or the other is wrongly named. Another good late day lily is the wild H. multiflora with 100 small flowers on its branched stems. I did not see one I used to admire at the arboretum labeled H. vespertina, a name not found in books, but a lovely small lemony flower like H. multiflora.

A truly valuable day lily (unlike most, which are pretty enough but which are rarely distinct enough to justify introduction, except that day lily gluttons require an annual feeding of new varieties, and no harm is done) is the small-flowered lemony 'Autumn King,' which only began flowering Aug. 19. Its 5 1/2-foot stems are elaborately branched and it looks as if it will bloom for a month.

The arboretum is in the forefront of breeding new crape myrtles. Some of them are red quite different from the familiar watermelon reds and much nearer scarlet. The color reminds me of that seen in certain old rambler roses like 'Turner's Crimson' and 'Excelsa' except the crape myrtles are even brighter. Some will find them garish, but the point is that quite new reds are coming along.

I particularly admired three others. One is reddish lavender, perhaps you could call it purple, with trunks almost as showy as white birches. Another is blue-lavender in which some of the florets fade to almost white, interspersed among the deeper lavenders, and it has a slight scent and reddish trunks when the outer skin falls off. Yet a third is lavender-pink with white trunks, and here and there the florets are blush or almost off-white, and it was my favorite. All these have quite large full panicles of bloom. Gradually, the best of the arboretum's crape myrtles, in all crape myrtle colors, are being made available to commercial nurseries.