C. L. Fornari - Gardening in Sandy Soil

by C.L. Fornari

My first experience with gardening was in central Wisconsin, where my family lived when I was a teenager. When we moved there, we were told that because of the sandy soil, the area was one of the last in the state to be settled and farmed. The earliest settlers chose to start farming in the southern part of the state, where the soil was a rich layer of loam. Later immigrants found that only the less desirable land was left; they had to find a way to farm in the sand that had been deposited centuries earlier by the glacier that had moved through.

Although it was first thought to be infertile, the sandy soil was perfect for growing potatoes, and what farmers initially considered to be the poorest farmland was nicknamed The Golden Sands.

Central Wisconsin farmers continue to grow potatoes, as well as other crops such as green beans, corn, alfalfa, and hay. The sandy soil that was once thought to be so undesirable is celebrated every year at the Festival of the Golden Sands.

Home gardeners who plant in sandy areas may not be moved to hold an annual festival, but there are many reasons for celebrating this type of soil. Potatoes and other root crops are not the only plants that grow well in sand, and many gardening tasks are easier when working in loose, gritty soils.

Most soils are made up of varying combinations of sand, silt, clay, and organic matter. The grains of sand are the largest particles of these four components, and the most irregularly shaped. Particles of clay are small and flat, allowing them to stack up with little air between them, while particles of silt are between sand and clay in size and shape. A good loam is a mixture of clay, silt, sand, and organic matter. Such soil is a gardeners dream because it is porous enough to provide good drainage and root penetration but contains enough clay and organic matter to retain some moisture around the roots. While you may be lucky enough to garden where the soil is ideal, most soil tends toward one or the other extreme. Gardeners must do their best with the soil they find in their particular area of the country.

Sandy soils feel gritty when you rub a pinch of dirt between two fingers. Because the grains are large and irregular in shape, you can distinguish them easily, and they do not pack tightly together. This irregular shape allows for a great deal of air between the grains. Water flows quickly through these spaces, so those who garden in sandy soils have excellent drainage. The roots of plants need air as well as water, so for most plants this good drainage is very beneficial.

Although there are some plants that like to have their feet wet, the majority of plants that we grow in flower and vegetable gardens do not like to grow in soil that is con-stantly wet. However, it is relatively easy for you to create small areas of your garden that will stay moist should you desire to grow plants that like constantly damp conditions (see page 19).

The air spaces between sand particles make it easier for the roots of plants to penetrate the soil. Root crops such as carrots and potatoes will reach their full size more easily, with fewer distortions in shape. The roots of other vegetables and flowers burrow deeply into sandy soil as well, and a plant with a deep root system is a stronger, more resilient plant.

Water is not the only element that flows more easily through sandy soil: The plentiful air spaces in sandy soils allow warm air to circulate freely as well. This is advantageous in the spring, because the germination of many seeds is dependent upon warm soil temperature. Warm soil temperature is the signal for many seeds to sprout and for established dormant plants to start their growth.

Air is also important for the activities carried on by the many organisms at work in healthy soils. Organic matter is constantly being broken down and converted into the nitrates that plants need for nutrition. Beneficial fungi and bacteria break down organic matter and destroy other organisms that are harmful to plants. (Gardeners often think of a fungus as being harmful to their plants, but in reality there are many more beneficial fungi than harmful ones.) All of this activity is accomplished more quickly in the presence of air, which sandy soils have in abundance.

Gardeners can always appreciate a soil that is more easily penetrated. Digging a hole in sand is less of a chore than is digging a hole in clay! Planting shrubs or trees in sandy soils requires little effort, and mixing organic matter into sand is a relatively simple matter not the back-breaking work of trying to turn soil amendments into clay. Clearly there are many reasons to celebrate if you are gardening in an area where the soil is sandy.

There is a flip side to every coin, as the saying goes. While we celebrate the advantages of gardening in sand, we must also understand and cope with the difficulties that sand presents.

Gardening in sand is almost a good-news, bad-newsjoke. The good news is that water runs through the soil quickly. The bad news is that water runs through the soil quickly. The irregular grains that give us good drainage also provide us with soil that dries out quickly, so it must be watered more often. Anyone who gardens in sand knows what it is like to water a plant deeply only to find it wilting from thirst three days later.The sand grains are hard and do not absorb moisture, and the air space between them lets water run right by.

Plants that grow in sandy soils are often nutrient starved as well as thirsty. Sand grains have nothing for nutrients to adhere to. In addition, the more frequent waterings necessary will tend to wash away nutrients that may be present, especially nitrogen. Gardeners must add nutrients to sandy soils more often, just as they need to water more frequently. Youll have to amend sandy soils with soil-enhancing materials that assist in the retention of both water and nutrients, so that the speedy loss of these necessary elements will be slowed.

Gardeners can often be heard talking about their gardens soil structure. This term describes the earth in a garden the minerals and organic matter and how they are arranged. Soil is primarily composed of mineral particles clay, sand, silt, or a combination of the three humus (organic material) in various stages of decomposition, and plant and animal life down to a microscopic level. As noted on page 2, the size and shape of the mineral particles determine the quality of drainage and root penetration in a particular soil. The humus acts as a sponge to hold water and nutrients. A perfect soil structure for gardening contains a loose mix of sand, silt, and clay particles, combined with a good amount of humus. This mix naturally clumps together in some small areas, but also contains air spaces between clumps and particles. Such soil structure has both good drainage and the ability to hold some water so that overall the soil is neither too wet nor too dry.

Few of us start out with a garden full of perfect loam, but just because we are given a sandbox to garden in does not mean we are powerless to improve it. There are many simple and inexpensive methods you can employ for successful gardening in sandy soil.

Amending the soil simply means adding what is lacking. What is lacking in sandy soils is something for both water and nutrients to hold on to. The addition of clay or silt to a sandy garden is a soil amendment, and, indeed, rock powders are available to use in this way. Although rock powders improve the soil structure somewhat and provide slow-release nutrients, they are too expensive to be used extensively by most home gardeners. If you have a local source of clay and are willing to do the back-breaking work of hauling it to your garden the amendment of sandy soils with clay particles will help improve your soil structure. However, there are easier ways to improve sandy soils.