Assuming there is sun enough for the gardener to have thought of growing vegetables, it is then sunny enough for perennial flowers, and I begin in this backhanded way to remind us of the truth, that in places the gardener calls "shady," such as beneath Norway maples, old oaks, beeches and elms, it is foolish to hope for hollyhocks or poppies.

The question, even where there is sun enough to grow a few radished (and therefore sun enough for perennials), is what kinds are best worth growing.

I have places, for example, where I could grow black-eyed susans (Rudbeckia 'Goldsturm') and these are "useful," as they say, for producing flowers through the summer, especially useful in late summer, and unlike most of the daisy tribe they endure a good bit of shade. The only trouble with them is I do not think they are pretty, and if there is one thing I am sure of, it is the folly of giving space to a plant one does not really care much for.

Each gardener must decide his own favorites. My wife could live happily without every seeing another daylily, for example, but I could not. On the other hand, she attaches much importance to the chrysanthemum, which I regard as so much neon straw, though I grow them anyway. It is well, of course, to reach compromises and not be too austere and pure.

Sometimes I worry about gardeners who find themselves suddenly with very little space to garden in, but with a head jammed full of passion for all these flowers that take a good bit of space.

It is hard, if you are a friend of the peony, to have to settle for less than 150 kinds, or less than 48 (if one must retrench) of the very best, or (horrors abound) fewer than three.

This past summer I ran into Helen Van Pelt Wilson, an enthusiastic gardener well known for her many books, and discovered she has been outrageously reduced to gardening on land the size of two large rugs. Such a relief, she told me, after those big gardens she used to keep up.

Her new book, "Successful Gardening with Perennials" (Doubleday), is full of sense and sympathy for those who have little space indeed, perhaps only 50 square feet, for their favorites.

Even so, she points out, there is pleasure from even a few plants. I would have planted her tiny place totally differently from the design she chose - I would mortgage my hound, if necessary, to raise the money to saw down that Norway maple she has, if it were mine - and the smaller the place, the more urgently I would insist on a pool for fishes and a water lily, if it were mine. And yet I would wind up growing many of the same things she does.

I liked her list of the longest-blooming perennials. So often such a list includes daylilies, which are not long-blooming as individual plants but boast of varieties blooming at different seasons, and this often confuses people who think that if daylilies bloom "from May to October" then their clump should do this. But no, the clump will bloom for perhaps three weeks and then rest until next year.

Incidentally, three weeks of bloom is very good for a plant.

But the perennials she cites as long-blooming do much better than that, and among them are achillea, Aster X frikartil, astilbe, coreopsis, dicentra (D. eximia only), helleborus, heuchera, nepeta, and (these I do not like as well as the first ones) coreopsis, gaillardia, oenothera, physostegia, veronica and viola (tufted pansies such as 'Chantreyland').

I would have added the Virginian spiderwort and tradescantia, but for her it has a way of dying down and looking shabby.

Perennials most likely to take care of themselves she lists as astilbe, baptisia, shasta daisies, coreopsis, dianthus (I would not list them in this category, but am enchanted they take care of themselves for some gardeners) dicentra, dictamnus, gypsophila, helleborus (once you get them going), hosta, Siberian irises (and I might add some of the spuria irises as well), linum, monarda, papaver (the Oriental poppies), polemonium and thalietrum. I have left out a few she mentions because I do not like them or else think them a nuisance, like Phlox subulata, which is all right until grass gets into it.

I feel that if Miss Wilson chopped down that maple she has she could put a lily pool right there, and could have some more sun as well. Another suggestion is to saw off all its branches and grow Clematis montana rubens up its stump, or a rose like 'Alberic Barbier' - this way one would have the height and some bulk without so much shade. But then some people perhaps like Norway maples; certainly there is no accounting for taste or (on the other hand) the long-suffering disposition of gardeners.

But back to perennials, she has chapters on phlox, irises, daylilies, peonies, shady gardens, edgings, ferns and so forth which have that particular kind of soundness (one can go for a page and a half without questioning a single thing) that comes of being a true gardener like Miss Wilson.

She has a cat named Snug. Some of my best friends have cats. As I understand it, Snug does only moderate damage, and does not at all ruin Miss Wilson's charming book. CAPTION: Picture 1, [WORD ILLEGIBLE] by Ken Full. The Washington Post; Picture 2, no caption, By Ken Full - The Washington Post