THIS YEAR for the first time in many years the question arises what to do with shrubs or perennials that arrive from a mail-order nursery before the ground is ready for planting.

Usually I like to get things in (roses, most of the hardly perennials, pansies) about March 15, but it is perfectly possible we shall still be having snow by that time this year. (We may, on the other hand, be having a spell of 80 degrees, which has happened earlier than this in Washington.)

Suppose the roses arrive in a blizzard. No need to take alarm. First, unwarp them and soak them in water for 24 hours or so - it does no harm to immerse the whole plant.

I was horrified to learn last year that some gardeners were unaware the entire root system must be immersed in the water. Somebody set the bushes in a tub with only an inch or so of water, thus allowing a good foot of the root system to be touched by the air.

No, no, no. Do not let the air touch the roots. I do not mean disaster will result if they are out in the air a few minutes, but I do mean it is important not to let the air blow about them even for half an hour.

The earth in the garden may be covered with snow. In that case, rather than attempting to dig planting holes, you should either heel-in the roses, or cover them with moist peat moss in the garage, or some other chilly place.

To heel the roses in, you have a trench ready, perhaps in the back of the garden, and lay the rose bushes in horizontally or diagonally and cover them with a few inches of unfrozen earth.

Some will say:

"Those idiot garden writers. If I had an unfrozen trench, I would also have an unfrozen rose bed and would not be heeling them in the first place."

But I am speaking about those thoughtful gardeners who have heavily mulched a spot for heeling-in plants.

Assuming - safety, I believe - that hardly anybody has thought of such a thing, let me say no harm will come to the plants if they are merely packed nicely in cold moist peat moss, sawdust or dirt, under a shed or in a cold attic or in a garage that stays cold.

Within a few days, improbable though it may seem, the cold will pass, the mockingbirds will start to sing, and the roses can be planted out in their permanent spots.

The worst thing in the world to do is to unwrap the roses, leave them in a warm room and wait. Never leave them unwrapped (or even wrapped) in a warm place.

But suppose you have only warm rooms? Then find a cold one.

The next worse thing to do is to leave them unwrapped for three weeks, until it gets warm enough for the gardener to feel comfortable outdoors.

No. No. You are not supposed to be comfortable. Do you think the little weasels and otters are comfortable? Plant while you still feel like cursing, that is my own rule, and I have abided by it man and boy for nigh no 60 years. As soon as the earth is clear and not frozen, then you must plant your hardy shrubs and perennials. Also - for I have noticed some are not aware of this - do not spare the water after the rose bush, say, is planted.

You might think that since it will drop to freezing at night that you should not water. But no you should positively flood the bushes immediately after you have earth around their roots. Say five gallons per plant at least.

The ground, even without a drop from your watering can or hose, will be virtual mud. Do not, therefore, pack the earth around the roots.

The earth must touch the roots, yes. But at this time of year, in soggy ground, you must not tramp about the plant with your feet. That is the point of copious watering - flooding - as soon as you plant. To bring the particules of soil close against the root hairs.

Finally, you should mound up the stems of the bush (the part above ground) with earth or mulch, gradually removing it as the weather warms. A week of warm weather after you plant will cause the leaves to sprout, and we may well have a crippling freeze then.It is not fatal, but it sets back the plant.

At the same time remember it will never do to leave the mounded earth around the stems once growth really starts. A couple of weeks, say, then - remove it.