Home Gardens and Lawns

Charles E. Kellogg.

The management of our garden soils follows the same principles as the management of field soils, but we use different practices. In our gardens we aim for variety, and we have a wide range of plants--grasses, annuals, perennials, shrubs, vines, and trees.

We try to have flowers and fruits through the seasons and ornamentals for sun and shade. Yet the total number of plants is small, and we can treat them individually. Even with simple hand tools, we have a chance to apply the principles of soil management over a wide range of combinations more precisely than the farmer can do for a few crops in big fields.

We have little choice in selecting our garden soils. Rarely can we choose level, stone-free, sunny, "rich loam" soils, which are recommended so blithely in the garden books and on the backs of seed packets. Once the location of the house is fixed, we must take the soils we find and make the best of them. Oftener than not, the soils around the house are not well suited, as they are, to the plants we want to grow, especially if builders have destroyed the natural surface soil and left thin topsoil over fills of trash and raw earth.

Thus many new home gardeners may begin with soils that are too hilly, too sandy, too clayey, too dry, too wet, or too infertile for good gardens. But good garden soils can be made from them.

By "garden," I refer to all the cared-for soils and plants around the home the kitchen garden, flowerbeds, lawns, and plantings of trees and shrubs. Included is a variety of plants that have unlike soil requirements. Some need shade. Others want full sun. Some prefer a slightly acid or neutral soil. Others do best in strongly acid ones. Some should have high soil fertility, others do well in poor soil.

The central problem of soil management in gardens is to develop and maintain a proper relationship between each plant and the immediate soil in which it grows.

Aside from pure luck, the gardener's success depends upon knowing two sets of factors: The requirements of the different plants he can grow and the characteristics of the soils in his garden.

Some plant can be found for almost any kind of soil as it is. And almost any kind of soil can be modified by management to grow any climatically adapted plant if one is willing to go to the trouble. Most successful gardeners try to find satisfying combinations of plants that require a minimum of soil change for good growth. Yet others go to a lot of trouble to change their soils to make them suitable for particular plants they want to have in their gardens. Some may even make drastic changes in a soil already about ideal for azaleas to have one suitable for roses, or the other way around.

One could hardly overemphasize the critical relationship between a plant and the soil in which it grows. Admiration of a plant in the catalog, at the flower show, or in a friend's garden is not enough of a basis for deciding to put it in our own garden, unless we know that its requirements can be satisfied by our garden soil as it is or as we can change it.

Gardening is an art, and many home gardens are outdoor living rooms. No one can say what is practical for home gardeners in general. Some are satisfied with almost any kind of green and growing things as long as the soil is neatly covered and the plants look healthy a sensible goal for persons with only a mild interest in gardening.

A large money budget is not necessary for a good garden, even on poor soil. Far more important is the work budget the care and attention the garden will be given throughout the season, not simply during a short spring bustle that is followed by neglect in summer and autumn.

THE PLACE for the garden is normally near the house. Even the kitchen garden is best there unless the soil in some distant place is a great deal better for vegetables and fruits. Near the house there is time to do the little things, before a pest, a drought, or a nutrient deficiency becomes serious. The watchful eye of the gardener is the best fertilizer for his garden.

To begin a garden, we need to know several things about our own place:

The basic soil conditions; the air drainage and frostiness; the water supply we can count on, both natural and artificial; the light that falls on the plants during the seasons; and the protection required against hazards of wind, tree roots, and animals.

TO LEARN ABOUT THE SOILS We Must dig not simply into the surface, but down to about 3 feet or even more, if deep hardpans or other barriers to roots and water are suspected. The lower layers of soil control the supplies of nutrients, air, and water for deep roots. The movement of water out of the surface soil itself depends upon permeable layers beneath.

Most soils consist of a series of definite layers, or horizons, one above the other, with different colors and other properties. The horizons have been produced by the longtime effects of the climate and vegetation acting on the mineral matter. The horizons collectively are called the soil profile, Very young soils may not have horizons. Examples include those in the flood plains along streams, recent sand dunes, or new soil made by earthfills. If the gardener digs into an ordinary upland soil and finds no regular horizons, he can be reasonably certain that the soil has been moved about and mixed up not long before.

The main things to look for are depth, texture, structure, color, drainage, the slope and exposure, acidity, nutrients, and contamination.

Depth. Three kinds of soil depth are important. The dark-colored surface soil is normally the most mellow and most fertile. This is deepest in the black soils developed under grass, like those in Iowa and the Dakotas. It is normally very thin in the desert and only moderately thick under the forest of humid regions. On steep slopes it is commonly very thin. Builders often destroy this dark-colored surface soil completely or may cover it with raw, earthy material from excavations.

Then we need to know the depth of the whole soil, both surface and sub- soil (or A and B horizons), over the raw substratum of weathered rock or other earthy material that has not been changed to true soil.

Finally, we should know how deep the whole soil and other loose, earthy material is over solid rock. The material under many soils is loose and porous to great depths. Other soils are thin over hard rocks with only a small space for roots and water storage. Such soils generally can support only drought-resistant plants that normally have shallow roots.

Texture. The relative proportion of sand, silt, and clay, or soil texture, of each horizon is important because it affects many other properties and because many recommendations are keyed to it. The texture in most soils changes from horizon to horizon. Commonly the subsoil, or B horizon, contains more clay than the surface soil above it or the substratum beneath it.

Classes of soil texture start with sand, which has only a little silt and clay. Then with increasing amounts of clay, the principal classes are loamy sand, sandy loam, loam, silt loam, clay loam, and clay.

With a little practice, you can easily distinguish them by squeezing a moist sample of the soil between your fingers. The sands are harsh and gritty, and the particles scarcely hold together at all. Loamy sands are gritty, too, but the particles cling together when moist. At the other extreme, clay can be squeezed into a smooth smear. The silt loam makes a rough and broken smear. Clay loams are intermediate. Loams give only a very rough smear; sandy learns give scarcely any.

Garden soils of intermediate texture the sandy loams, loams, and silt loams are easiest to handle. Sands and loamy sands are permeable, but they hold rather small quantities of water and are said to be droughty soils. Clays tend to become hard and massive unless they are handled carefully.

Structure. The individual soil particles in the ideal garden soil are grouped into stable granules or crumbs. Next best are blocky, nutlike aggregates, between which roots and water can move. Worst of all are the structureless soils.

At the one extreme are sands, in which each grain is by itself. Such soils hold little water between rains and are easily blown about by the wind.

At the other extreme are massive soils with no regular structural forms. Commonly clayey soils deficient in organic matter become massive if plowed, stirred, or walked on when they are wet. But massive hardpans can form from loams and even from sands with some cementing material to hold the particles together. Wherever they occur within the depth of normal rooting for garden plants, such massive soil must be reworked to make it granular or blocky. It is not enough simply to break up massive clods of clay. Organic matter must be added, or the fragments flow back together into masses when they are wet again.

Color. Soil color by itself is not important, but it suggests other conditions that are. Color, along with other evidence, can tell the gardener a great deal about drainage, the amount of organic matter in the soil, and the general level of productivity.

Brownish-black and dark-brown colors generally suggest a good supply of organic matter. In wooded areas where the normal upland soils are brown, black colors in the surface of soils in low ground suggest muck and poor drainage. Well-drained soils developed under tall grasses, like many in the Middle West, have black or nearly black surface soils. But a few black soils are poor in organic matter and easily lose their structure and become massive.

Solid red or yellow colors generally (but not always) suggest fairly good to free drainage. Yellow suggests leaching and a low supply of plant nutrients. So do the grays or whites in upland areas of good drainage. But in low ground, especially if the surface soil is nearly black, gray horizons (called gley) indicate poor drainage too poor for ordinary garden plants. White colors in dry regions suggest soils too salty or too limy for most plants.

Some horizons beneath the surface are mottled. Imperfectly weathered rock just above the solid rock may look like this. But the commonest cause of mottling in soils is imperfect drainage, now or in the recent past: The soil is saturated with water, or waterlogged, part of the time and pervious to air, or aerated, part of the time.

Drainage. Imperfectly drained soils that are well drained during the summer and wet only in winter and early spring can support annual garden plants, but the roots of perennials cannot live over the winter in them. Even annuals do poorly if periods of waterlogging occur during their growing seasons. Often there is little evidence in the surface soil alone of poor drainage beneath. Thus it is important that you identify such conditions in advance so you can take appropriate steps for drainage or for plant selection.