A living palette

TRANSPLANTING an idea from Miss Gertrude Jekyll, that notable Edwardian gardener and garden designer - author of ''Colour in the Flower Garden'' (1908) - Vita Sackville-West dreamed up her ''White Garden'' at Sissinghurst in Kent. Of the admired Miss Jekyll, Miss Sackville-West (wife of Harold Nicolson) wrote that ''she was usually right'' and described her as ''that grand gardener to whom we owe so much.''

Miss Jekyll thought of herself as ''painting with living plants.'' She espoused the practice of the ''wild'' or informal garden (as opposed to the patterned, unnatural ''bedding out'' of plants) and then explored the aesthetic possibilities of planning within that naturalness. She experimented with associations of color. ''She took,'' writes F.R. Cowell, ''immense trouble to hit upon pleasing contrasts, such as a bed of white tulips in a patch of the silver-grey, velvet leaves of Stachys lanata.''

That single instance of associating one plant with silver-gray foliage and another sporting pure white flowers - not so much a ''contrast'' as a subtle harmony of related tones - might have been the very basis of the Sissinghurst ''White Garden.''

This garden not only still exists today but is visited every year by hordes of people. It is one of a number of gardens-within-the-garden at Sissinghurst, but it seems possible that many find it the one that remains strongest in the memory.

Throughout Sissinghurst there is a gardening philosophy which combines the wildly natural and the strictly planned: a partnership of freedom and restraint. It is one of the special qualities of the place. And in none of its parts is this truer than in the ''White Garden.'' Plants themselves often seem to know few bounds to excess. Think of irises, with their knife-blade leaves: When in full flower a clump of bearded irises is as extravagant with color as a forest fire is with flame. Think of rambling roses in summer, abundant with leaf and flower, liberality itself.

But if the flowers are white, or the leaves silvery, there is a contrary current, an opposition of simplicity and clear, unexaggerated form, to the showering largess. Whiteness is immaculate, and it is more like sculpture than painting. It is not a negative draining of color from a form: It is positive, single-minded, and ultimate. One of the excitements of the ''White Garden'' is that it brings together white-flowering varieties of plants normally associated with one other or many other colors. Delphiniums are generally blue (though newly developed red delphiniums are going to be seen in public for the first time in July, at Liverpool - the result of about 30 years' work in plant breeding). But the ''White Garden'' contains white delphiniums. The irises are white. There are a number of white roses, one appropriately called ''Iceberg.'' There are tall white foxtail lilies, white clematis, white pansies, white columbines, and white Turk's Cap lilies.

It is interesting that Vita Sackville-West wrote about her dream plan for the ''White Garden''(in an article in the Observer in the late 1940s) before it was made:

''I hope you will survey a low sea of grey clumps of foliage, pierced here and there with tall white flowers. I visualize the white trumpets of dozens of Regale lilies, . . . coming up through the gray of southernwood and artemisia and cotton-lavender, with gray-and-white edging plants such as Dianthus Mrs. Sinkins, and the silvery mats of Stachys lanata, more familiar and so much nicer under its English name of Rabbits' ears or Saviour's Flannel. There will be white pansies, and white peonies, and white irises with their grey leaves . . . at least, I hope there will be all these things. . . .

''I cannot help hoping that the grey ghostly barn-owl will sweep silently across a pale garden, next summer in the twilight - the pale garden that I am now planting, under the first flakes of snow.''

With a dash of poetic fantasy, this visualization was like the first sketch of a sculptor in advance of the final work.

I have seen the ''White Garden'' on a hot summer evening, and it had the coolness and the sparkle of pre-nightfall moonlight. I didn't see a barn owl. Doves would have been just as appropriate. There is nothing ghostly about the garden: It has all the cozy generosity and profusion of the ideal ''English Cottage Garden'' so favored by the Nicolsons, but its color-music is more classical than emotional. The inescapable greens (dark, bluish, or gray greens) of leaf and stem provide a firm harmony to the chalk and ivory, snow, paper, or alabaster of flower forms that are the lucid and bright melody of the garden.