The garden of Powis Castle in Wales has improved out of all recognition in recent years, and its great natural advantages have been enhanced with some of the finest plantings in the United Kingdom.

To begin with, the great red sandstone fortress, built in the 1200s, sits atop an eminence commanding the surrounding lowlands and huge terraces descend five or six levels to a flat land at the bottom. From afar one sees the vast pudding-like yews clustered at the base of the castle and above the main terraces. They are the size of small houses, seemingly rooting into the side of the cliff. There is doubt when they were planted, but possibly 250 years ago; in any case they set the scale and the tone of the great garden, promising that here there will be a monumental treatment of the land.

The terraces are about 850 feet long, outlined by costly balustrades of stone, and the walks down the center of each terrace are wide, allowing a number of people to walk abreast. Lead statues of lively shepherds rise from piers in the balustrades of the main garden terrace, looking out to the valley, and these have been painted white. At first this was objectionable and glaring, but now that sufficient dirt (or perhaps I should say natural incrustation) has settled on them they look much better. Conservation specialists are commonly worried about everything the weather can do to statues, and the white coating is designed to protect them.

The easiest way to view any terraced garden is to go to the bottom, then work your way up. Otherwise, having dawdled on the way down to examine every interesting plant, you are suddenly faced with a mountain to climb, and no reasonable excuse to break the ascent.

It's clear without much insistence on the point that a series of terraces each a sixth of a mile long, crowned with a massive castle at the top and commanding sweeping views into a valley, present a background to the garden that is very tricky to achieve in a tiny town garden. The importance of scale, however, holds true at Powis or a Capitol Hill garden equally, and reasonableness is critical in any garden, though it is easier to be reasonable over some acres than over a few square yards.

Although far to the north, the garden benefits from the mildness brought by the Gulf Stream, and such plants as Cordyline australis and Phormium tenax (neither hardy in Washington, even in their hardiest strains) grow well. Another good plant we do not grow is Buddleia colvillei from Sikkim. But against the top terrace wall also grow Magnolia soulangiana and M. grandiflora, both of which grow better in Washington than in Britain.

Fuchsia magellanica is a hardy fuchsia we rarely grow, though it is hardy in Washington and should be planted more. It abhors drought and is happiest grown against a wall facing north, and even so it appreciates watering during the summers (and it drops its leaves in winter but should not be cut down until April).

The beautiful Mexican orange, Choisya ternata, has orange-blossom flowers in clusters. It is occasionally offered for sale here but is not reliably hardy. If we attempt it, we should expect to lose it in a winter of zero temperatures, but against a wall it would probably pull through if given a good mulch and some burlap to break the icy winds. Even in gardens where a low of 24 degrees is thought exceptional and terrible, such plants as the choisya will be killed outright if there is an exceptionally cold winter. Fortunately, many rather tender shrubs grow quickly -- the choisya does -- so such risks are well worth taking.

On one wall there are trained pear trees and hanging over the wall among them are such wild roses as RR. soulieana, wichuraiana, brunoni and filipes. One of the worst things about a small garden is that we cannot grow such wonderful wild creepers as these, giving them all the space they really need to display their full beauty.

Wild cyclamen are often planted beneath yews in Britain, and C. neapolitanum with its soft pink autumn flowers would do equally well beneath our own yews. I noticed this little cyclamen did particularly well, once it got started, beneath a big willow oak in my Tennessee garden years ago.

Carpenteria californica, Arbutus unedo and the bay tree, Laurus nobilis are other plants we cannot manage here, so I admired them there. After many years (as a rule) the gardener finally gets to the point that he can admire trees and flowers without a burning pain of covetousness.

Other plants include such familiar old friends as Cotinus coggygria, the winged euonymys, the two commonest plumbagos, Hypericum calycinum, and the same hybrid musk roses we grow (Buff Beauty, Penelope, Felicia, Wilhelm and so forth). There are uncommon clematis (CC. pavoliniana and uncinata, which we should probably look into) along with such fine old stagers as the climbing roses 'Mme. Caroline Testout' and the newer rambler, 'Crimson Showers.'

There are hecychiums, clerodendrums, senecios, along with our wild native trumpet vine. A beautiful plant we rather ignore is Abutilon vitifolium, and a couple of its hybrids, with blue saucers through the summer. It is tender but would do in a tub moved into shelter (not necessarily a heated greenhouse) for the winter.

Common rue (Ruta graveolens) makes an elegant low hedge or edging to borders and is used for this purpose more often in Britain than here, though it is so easy to root new plants from cuttings taken now that I wonder why we so rarely see it. But remember some people get a rash from rue, said to be as bad as poison ivy, so try it out gingerly.

A number of apple and pear trees, planted in 1890, are trimmed to pyramid shapes, with circular beds around their trunks, each planted with a different ground cover. Stachys lanata, rue, lavender cotton, lungwort, London pride and creeping Jenny in a gold-leaf form, and variegated dead nettles are the plants used as carpeters. This would not suit me, but it was quaint and in a way pretty and is a useful idea for gardeners who want a long-lasting colorful effect without much bother.

Finally, an apology for saying recently that the rose 'Aglaia' was named for one of the Muses. Aglaia was one of the Graces, of course. I misspoke. Which reminds me that anoher rambler, also named for one of the Graces, is 'Thalia.' This is a white rambler nobody ever mentions and I do not know where anyone could buy it, but it is a quite fragrant white rose in clusters like small melons. The first time I saw it (in France) I wondered why it is so little known even to lovers of out-of-date roses, since few ramblers are as sweet or as showy.