CLEMATIS AND caladiums may seem an odd combination, but this is the right time of year to comment on both.

First, the large-flowered clematis is not a difficult climber, despite the unattractive habit of sudden death. Much of the misery of growing clematis comes from simple ignorance, and there is no excuse for denying yourself this most gorgeous of climbers merely because you don't know what to do.

Sometimes you see clematis growing up lamp posts in front of houses, with the grass growing right up to the stems and the vines growing in the full blaze of the sun. The mere fact they so often succeed in such places is proof the plant is not that great a nuisance, and yet the usual cause of failure is in getting the plant established in the first place.

It is hard to remember that the clematis vine starts putting out leaves in January or early February here.

Clematis plants are often sold, each vine in a little cardboard box, in February at hardware stores and other unlikely places, and usually these are splendid plants and splendid buys.

But the gardener usually does not think of planting clematis until mid-April, which is far too late (though it can be done, with prayer).

The clematis vine in the little box (the roots wrapped in a plastic bag) naturally starts growing along in February and by March the shoot may be 6 or 8 inches long.

Unfortunately, stores are heated, and the clematis grows like mad in its little plastic bag, and by March the growth is terribly soft and drawn, especially since it has no sun. Often the shoots are white or very pale yellow-green and look sick.

Now if the gardener takes such a plant and plops it in the ground -- which in March is commonly like plastic and rather soppy -- the clematis shoot will perish almost certainly. Even so, it will often send up a second shoot from below the ground. Sometimes it will do this in a few weeks, sometimes not till next March.

Now, ideally the clematis is planted outdoors in late October or up until Christmas; but there is little point in saying this, since stores never offer clematis then, and few gardeners seem to get around to ordering from specialists for fall delivery. And when the clematis arrives on Nov. 4, say, the gardener is certain it's dead, since the old leaves are dark brown and crisp, and there is no green on the stem even if you scratch it. The gardener, like Lear, makes a great speech that he knows when one is dead, etc., and it must be a nuisance to nurseries to deal with the almost certain complaints of gardeners that their clematis, received in November, are dead.

It is almost impossible to persuade inexperienced gardeners the clematis is in superb shape, despite those utterly dead leaves and a stem no thicker than a piece of string.

The experienced gardener plants in November, all the same, and the vine starts shooting up in late February and early March, and everybody is happy.

But back to the clematis at the store, in early March, with the sad-looking pale shoot.

We shall certainly have killing frost after that, and this pale weak sun-starved shoot will certainly perish.

But instead of planting it out, to certain death, plant it in a pot, in potting soil. Be extremely careful unwrapping the plastic bag. The point where the stem meets the roots is fragile and you must be careful not to break it. This is truly important.

Having unwrapped the plastic, soak the whole plant in water. A small mixing bowl in the kitchen does well, if one's spouse is not in the house.

Then very carefully plant the clematis in a 4-inch pot (nothing magical about 4 inches -- any pot that is not obviously too small will do) with a small wood stake for support and water it thoroughly, until the soil is absolutely sopping.

Now set the pot where it gets some light but no sun, and after a couple days move it to a window where it gets morning sun, then to a south window where it gets all the sun it can.

On warm sunny days in April, set the pot outdoors, but bring it in at night and during storms. By this time, needless to say, the leaves are normal full green and the plant is growing briskly up its little wood stake.

Toward the end of April or any time in May, carefully turn the pot upside down (holding the soil in your hand, of course, so you don't dump the clematis on the ground) and remove the young vine in its ball of dirt. Plant it in its permanent position outdoors.

Water well, and there should be no further problems.

There must be something for the vine to climb up, like wire or nylon string or slender wood dowels. Later the clematis will be able to manage inch-thick wooden trells, but not at first. On a heavy wooden post or pillar, simply attach a length of woven wire fencing or other wires, which the vine will cover.

The clematis roots should be shaded. The roots in the shade and the tops in the sun is the general idea. Where there is a choice, plant the clematis on the north side of the post, or shade the base of the plant with a low shrub or, failing that, a slab of stone or bricks, to keep the soil cool.

All the large-flowered clematis can succumb to a fungus called clematis wilt. This usually strikes just as the irises are coming into bloom, and just as the clematis vine appears to be in luxuriant health. The shoots will wilt and fall limp.

Cut all wilted growth out, below the trouble, and throw it in the garbage (do not leave it about) and hope for the best.

Sometimes the entire plant goes. Again, cut out all the wilt at ground level and hope for new shoots from the base, and remember the vine may shoot up vigorously the next spring.

This is all very distressing when it happens. I am sorry, but I did not design the universe, so don't look at me. But the chances are the fungus will not appear. We see that humans have heart attacks, but that has not deterred the production of children that I can see, and clematis wilt should not deter anybody from planting a clematis.

The usual trouble, as I have seen it, comes not from the disease but from planting out vines with soft growth when they are too tender to bear open weather.

Now my own c. texensis arrived with only three tiny leaves on it, and this clematis can be far more difficult and miffy than the large-flowered kinds usually found in gardens. And yet by keeping it in a pot until it was strong enough to take its chances (birds, squirrels, hounds, winds, hail, etc.), I now have a fine plant that blooms its head off.

When one says this of any plant, it usually drops dead on the spot, but I have knocked on wood.

And if I did not know what I was talking about, I would not be recommending this pot business (admittedly a great pain in the neck) to you. But I know it is worth doing, and I know the results will repay the bother a hundredfold.

Ideally of course you order your clematis for fall delivery and you avoid all this pot business, yet few gardeners can resist those little boxes at the stores at this time of year (I cannot) and they work out very well if you give them this little extra help.

Christopher Lloyd's book, "Clematis," is excellent. If your library does not have it, suggest they get it.

Most gardening sections of most libraries are full of books utterly worthless, you will in time begin to notice. Lloyd is English and I think librarians have the odd notion that English gardening books do not apply to our conditions.

Most American garden books that I know, on the other hand, do not apply to anything at all, since the author is commonly ignorant, and you will find little indeed to help you when you acquire a clematis in a box in March, for example.

Now fancy-leaf caladiums, to turn to them, are important in those dank shady holes that many townfolk have to call for a garden. Places where the brick is mossy and where the main gardening task is to clean up the dog messes.

Yet such a garden, with a couple of chairs and a basin or pool for goldfish, and a few clematis vines (if there is enough light for them to struggle up into the sun), can be very pleasant -- or better than nothing.

And if it's all you've got, you may as well call it paradise and get on with it.

Caladiums are worth their weight in gold in such shady gardens. You can acquire a half-barrel that once held whisky, perhaps, and fill it with good light soil: lots of leaf mold and peat moss and sand nicely mixed.

You do not want heavy loam or plastic clay.

The caladium bulbs should be 1-1/2 inches in diameter, to produce the finest leaves, and they should be started in barely damp peat moss or sphagnum. Just a 3-inch deep wood box (or clay pots will do) filled with peat moss. Set the bulbs an inch below the surface.

If convenient (and it never is), give some bottom heat.

I have tried setting the box on top of the furnace and also on top of the hot-water heater with excellent results, but it all depends -- you don't want to cook the things.

Once the bulbs are sprouted well, plant them individually in smallish pots of the light soil.

Then in mid-May plant them in the great tub (or in a shady border along the terrace, etc). These fancy-leaf creatures do not require direct sun, and will in fact burn if given very much sunlight. Some more than others.

The leaves are 1 to 2 feet long, each growing on its stem direct from the bulb. The most popular, and maybe the most dramatic, is called Caladium candidum, which has a white leaf with green veins.

There are a number of other white-and-green sorts ('Aaron' and 'White Christmas' among them). While others are deep rose with green borders, or deep bronzy red blades with green edges, or white with red veins.

Once I planted a batch of mixed colors, not labeled as to variety, and was well pleased with the results, though gaudy and startling. You may find (but then you may not, either) the white with green veins is the best.

Caladiums must never be allowed to dry out, once they start growing. They are good by a shady terrace or by the pool because you will not forget them and their thirst.

In October, you dig them up and store them dry, over winter. The bottom of a bedroom closet (preferably someone else's will do quite well.

If this peat moss and pot business seems too much, you can plant the caladium bulbs in the earth outdoors in mid-May, but in that case the leaves will not be large by June, like the ones started indoors.

Sometimes the supply of bulbs gives out in spring, so they should be ordered (or acquired at stores) now, while you think of it and supplies are good.