There is much written about planting in fall or planting in spring; about planting large trees or small trees; about pruning, grafting, or the general management of trees above ground; but about the tree beneath the ground few people know much. We are taught about the tree; but about the earth which is to sustain the tree, how little do we know? So much however depends on soil culture, that a few seasonable hints on this topic will not be thrown away.

We read of the wonderful success of the English gardeners with Rhododendrons, and other "American plants," in which are included a large number of the Ericaceae or Heath family, and we are apt to. attribute it to the moisture of their climate, which is undoubtedly favorable to the success of evergreens of all kinds; but when we remember that these plants are all natives of our country, the suspicion naturally arises, that it cannot be wholly to the atmospheric conditions that their success is due, - nor is it, - but it is rather to the great attention which is there paid to the proper culture of the soil. All plants require air and moisture for their roots, and when these roots are of a delicate, hair-like nature, extra care has to be expended in order to supply these conditions. If the water remains long in the soil, there will be no air there. The earth must be porous for the water to run rapidly away. On the other hand the earth must be of such a character that, though the air is permitted to pass through, moisture will be retained. A soil that is perfect for these hair-rooted plants, may be called a spongy soil, and yet of such a character that water can scarcely be pressed out of it.

Now those who grow Rhododendrons and Azaleas in the old world, would never think of planting in stiff soil, but they go to great pains to get the soil just as they need it for the success of the plants. It is no uncommon thing for the earth for the American bed to be brought fifty or even a hundred miles. The writer has seen peat soil for the Rhododendron beds brought in vessels and unloaded at the docks like loads of coal. If the grower wanted these plants he would not say : My soil is limestone and Rhododendrons' will not grow in that; but he digs out the limestony earth to a depth of two feet, and supplies its place with the peat, and thus he overcomes the natural antipathy of the earth. Peat is very good, it is so full of air and spongy, but it is by no means essential. Anything that will give an open, porous, spongy soil answers the same purpose. The writer has seen the Rhododendron growing as well in a pile of quarry refuse - the broken, useless stone, - after some manure has been placed in it, as he has ever seen in a bed of peat.

In fact where peaty soil cannot be had, broken stone or gravel, or anything that will keep the soil aerated and moist, will do nearly as well.

And the lesson is good for all trees, as well as for Heaths, Andromedas, Kalmias, Rhododendrons, and such like trees and shrubs. Nothing likes to have water about its feeding roots, but insists on having air. Take a tree which grows in or nearly in water, in a state of nature, as a Cypress, an Alder, or Gum tree, and plant it in a swamp, it will not grow, or do very poorly, if at all. Naturally, it is only the few larger members of the tap root class that go straight down into the swamp. The feeding roots keep at the surface, through the moss or in the spaces that are moist always but never wet. But in planting we bury the roots of all kinds beneath the water where the air is not. So, if we want to plant a tree in a swamp we bring earth, or throw it up in a hillock, and plant the tree above the level of the swampy surface, and let it send its roots down of its own sweet will. The writer profited by this knowledge in his attempts to cultivate the Mammoth tree of California. When in California himself, he saw that these giants of the forest were originally swamp trees, though through the course of ages the localities had dried somewhat.

Hitherto the trees in the East had been planted on ordinary garden ground, except a few in a moist ravine on the grounds of Ellwanger & Barry, at Rochester, New York. On the writer's return from California, trees were planted in a swamp so soft that a horse that once wandered into it could be barely got out alive. But the manner of planting was by getting a barrel, taking out the bottom, planting it in the swamp so that a foot or two was above the level, and earth filled in. On these elevations the Mammoth trees were planted, and they have grown like willows. By the time the barrels rot away, the surface roots will themselves find a way to creep over the surface soil. Many good gardeners who have wanted to plant trees on wet ground often ridge the earth, or throw it up into mounds and plant on them - on the ground in some sense, instead of beneath it - and then have surprising success.

Not only for trees and shrjj-bs, but for flowers and plants of every kind, the first essential of success is an aerated spongy soil. This is often naturally the case; but when not so, nothing is usually more easy than to make it so. Even piles of corn stalks, brushwood, or similar material, buried deep in the soil, will often help to keep a flower bed or bed of shrubbery open and porous when nothing better is at hand.