Earthman has skipped town to investigate, in depth, which of 9,011 varieties of 'Whatdidies' to plant next week. There will be a full report next Sunday. In the meantime, he says this earlier column contains advice which can't be repeated too often.

THE LORD, as we know, moves in mysterious ways, and if you are by any chance asking how it happens that a wholesome gardener like yourself ever wound up stuck with the atrocious clay of this capital, then join the general chorus.

There are gardens here - not that you'll be lucky enough to inherit one, probably - where the soil is more or less reasonable, tillable, friable and livable, but we may as well get on to the more common case of soil more tenacious than a political fanatic and just about as attractive to try to work with.

In theory, as garden writers never tire of saying (it costs them nothing, after all), the stickiest clay can be transformed into celestial loam. This requires merely a 3-inch layer of sand, a 5-inch layer of well-rotted manure and so forth.

The trouble is that first, nobody knows where to buy that much manure that's been stored dry for two years, and nobody has money enough for several truckloads of it even if it were to exist, which it doesn't. Secondly, the sand (you might inquire the price of sand nowadays) is more easily recommended than purchased, and finally there is the slight trick of double-digging the garden, getting the sand and humus thoroughly incorporated in the top 20 inches of the surface.

Only the rarest gardener can be persuaded to dig a minimal hole to plant a tree or a rose bush in, and it is largely wasted breath to suggest operations that involve major reworking of the soil.

In many cases the dual solution is simple enough - install a system of tile drains and raise all of the beds 6 inches above the general level of the land. Apart from the costs, which I leave you to have nightmares about, this means moving anything that happens to be growing at the moment.

If all this is true, then why bother to mention it, since clearly there is not much that the average gardener can do about it.

It is precisely because nothing can be done, for all practical purposes, about the nature of the clay, that it is urgently important to make the best of it, not the worst.

The first thing to keep in mind is that a thin sandy soil or a chalk soil or a fragile layer of loam over granite is much worse than heavy clay. As one might say, it is better to be hanged than drawn and quartered.

Convinced that there are things worse than heavy clay, then, we should note a few things to do and not to do with it:

Do not work with it when it is wet. The soil itself suggests as much, since it is totally unworkable, but this does not deter some gardeners who blithely slog about trying to dig it off and on all winter.

This is not merely pointless, it is criminal. The nature of clay is tiny, densely-packed particles with very little air space between those particles. Manipulating it while wet accomplishes the disaster of driving out what little bit of air there is in the soil. Clay dug when wet and tenacious will make an excellent substitute for concrete when it finally dries out in the spring, and you not expect anything less than a dandelion or the devil himself to flourish in it.

Since clay should not be handled when wet, and since it says wet in Washington all winter, it follows that planting of a major kind should be done early in the fall, or else in spring. When you read recommendations to plant most woody things in the fall (November is ideal for many) this presupposes a dry and workable soil. If your soil is heavy, gummy clay that appears to be getting on toward epoxy, then do not plant in it no matter what the books say. Either do it before mid-November; protect the planting area with a cover to keep it dry; or else wait till early April.

Lilies-to cite merely one example-are best planted in November or even earlier (not that you can usually get them earlier from dealers). This is better than planting the bulbs in early spring. On the other hand, planting them in the spring is vastly better than planting them in November in soggy heavy soil. If there is one thing lilies abhors (and there are many things lilies abhor) it is heavy wet clay, and they will simply not survive in it.

There is no substitute for providing what lilies demand - a porus, humus-filled, somewhat gritty, well-drained soil. Sooner or later, usually sooner, they will perish in heavy clay no matter what month they're planted, but to plant them in a cold quagmire is absolute folly.

Thus, we see that spring planting is better on heavy wet soils, even though the only permanent solution heavy wet soils, even though the only permanent solution is to change the soil itself to suit the lilies. Or (an obvious solution no true gardener will tolerate) forget the lilies.

Do not walk about or otherwise compact clay soils in fall and winter. If you must poke about to see how things are doing, use planks or flagstones to stand on.

If part of the garden is not begin used, ridge up the soil, by digging parallel trenches and throwing the earth to the sides. Handle it as little as possible. Let it sit all winter. Compost (which there will never be enough of) may rest in the trenches, and so may fresh manure. This may all be dug in and leveled next spring. The texture will be somewhat improved - it will be great for growing annuals on, things like zinnias and marigolds and sunflowers. The following fall it will be suitable for planting bulbs in.

Ideally, there should not be any such thing in the garden as tenacious as clay-there should be enough leaf mould, peat, rotted manure and whatnot dug in over the years so that the soil is perfect.

But things are not always ideal, so in the meantime keep in mind the overriding rule for clay - don't compact it, which means don't work it or press it when it's wet.