DAYLILLIES HAS A way of taking over the garden, not because they multiply rampantly (they do not) but because their survival rate is greater than almost anything else.

From the middle of June through July they brighten the scene, and the end of the first week in July usually finds them a mass of flower.

Some, ofcourse, bloom much earlier and are even finished before June is out. The first surge of the small yellow "Bitsy" is passing (it will bloom off and on the rest of the season) and the wild Hemerocallis flava, the "Lemon Lily," also is finished for the year. The wild tawny H. fulva, which does much to brighten city alleys, is in full bloom now, and in the garden the early red "Gusto" has passed its peak and the red "Alan" is in flower.

The tall clear yellow "Lady Bountiful" almost always blooms on June 16 and makes a generous splash on stems that arch over and sometimes flop - a grand flower for planting in alleys - while for small town gardens the equally early but much small and neater "Corky" is admirable.

"Bitsy," "Corky" and "Golden Chimes' give a succession of flower for some weeks in lemon to gold, all of them with small flowers but the last two are waist high. If a town garden had a water basin at the end of it, backed by some evergreen vine, it would be nice to surround it with "Bitsy" and one clump of the other two.

And if there were a patch of the early-March-blooming Crocus "Goldilocks' followed by three bulbs each of the lemon daffodils "Spellbinder" and (later) "Binkie" or "Daydream" and then a half-dozen ivory yellow tulips "Jewel of Spring" and the bearded iris "Ultrapoise" the range of yellows could be spread over some months. The daylilies might be followed by a plant of the cushion chrysanthemum "Jackpot" and finally, as the snows start, a single yellow Korean-type chrysanthemum with flowers no bigger than a quarter.

It is easy enough to understand the addiction of gardeners to daylilies.Some people in town have a thousand varieties, and many more have a couple of hundred.

Where there is endless space, but not endless labor, a vast collection of daylilies is easier than a collection of irises, roses, peonies, chrysanthemums, dahlias or anything else.

But even where there is almost no space, a few daylilies (as i have suggested, around the bird bath or small pool) will more than justify the room they take in a garden only 20 or 30 feet square.

Sometimes new gardeners, viewing great batches of flower in a large garden, think there is no point growing only two or three in their tiny gardens, but they should not be in any way discouraged.

An arbor to sit in, covered with a grape vine, and some soft-colored pavement of brick, stone or concrete is the beginning.

The background fence or wall should be high enough to give a really strong sense of enclosure, but a cheap wire fence will do quite well provided you can't see it much (either planted with vines or planted in front with such things as a holly, camellia, photinia, nandina and osmanthus, for example) and then all that remains is to use a few flowers, coming along from March to November, for color.

Nobody should imagine that a 6-foot-square holding the bird bath and the yellow flowers I have listed as an example will be any riot of color from late winter through the fall. But there would be enough to keep the gardener looking forward week after week through the year.

Sometimes young families have a garden with more room than they know what to do with, but no money; and they are likely to say that even if daylilies only cost a dollar or two per plant, they cannot afford to plant beds of them. But there is no need to.

Maybe a word to gardeners with good-sized collections would provide them with daylily seeds. Planted in the fall, they would bloom two summers later, and crosses from such current varieties as "Winning Ways," "Iffy" and so on would give plants that would satisfy almost anybody.

Last year I made a batch of crosses (putting the pollen of one daylily on the pistil of another) and gave the seeds to a gardener outside London. Daylilies are not so widely grown there as here.

I suspect that from several hundred seeds they will find a number of plants they will want to keep.

This does not mean that the daylilies raised from seed by a gardener in a few spare feet of ground will be as fine as the newest named varieties. The odds are ferociously against that. But the flowers raised from seed will be as colorful as any and will furnish the new gardener with a lot of flowers that otherwise he could not afford.

Something of the range of colors and shapes now found in daylilies will be seen July 8 (1 to 5 p.m. only) at the National Arboretum, where the regional daylily society will hold its free show.

At such a show you can jot the names of the ones that appeal to you, and (from specialists in daylilies) buy the ones you can't resist. The catalogues of specialists often offer collections of daylilies for beginners (or anybody else) at specially low prices, and in any case the older varieties are cheap and as good for garden purposes as any.

I mentioned "Lady Bountiful," a quite beautiful thing, but I doubt any catalogue in America now lists it, since so many better varieties have come and gone since it was popular in the 1950s. One can do much worse than paw through catalogues and order the cheapest varieties in the colors he wants. Usually the gardener is astonished that the cheap ones (which he thought for some reason would be ugly) are so beautiful.

Any time in the next few weeks will be great for visiting the daylily collection at the National Arboretum. That planting is much better now than it was formerly, and every gardener interested in daylilies should visit it. All the kinds are labeled.

Daylily plants increase more rapidly when given full sun, plenty of water and a good soil, the sort you would give tomatoes or roses. In my experience, at least, they respond to water more than to fertilizer, but they like a nice rich soil if they can get it.

They can be planted any time the ground is not frozen, but July through mid-September is best. I have grown them in almost total shade, and in virtual pasture land crowded by coarse grass, and they bloom a little in such places, which is more than any other garden flower will do, but of course that is not the way to grow them.

They do not need pampering, or even extra water in May and June (which they greatly appreciate). But they do like - and need, if they are to show their greatest beauty - sun and ordinary good garden soil. Incredibly enough, they never need staking, and I have never sprayed against bug or blight. CAPTION: Picture, no caption