Getting Down and Dirty with Dirt, Part 1 - Soil Types
There are basically three types of soil, sand, silt and clay. Most soils are a mixture of the three. Types of soil vary from one geographic region to another, but can also vary from one part of your backyard to the next. Knowing which type of soil you have in your landscape is essential to proper plant selection and care.
TIP: Our expert gardening advisor, Susan Patterson adds, "It is always a good idea to have a soil test conducted before planting. It may be necessary to amend your soil in order to increase its nutrient content."
Clay consists of small particles (less than 0.002 mm in diameter). When dry, it has a smooth texture, although it is usually in the form of rock hard clumps. When wet, it is very sticky. Clay soil generally holds nutrients, but doesn't let air or water through. Its compact nature makes it very heavy and difficult to work. It is a good soil for growing vegetables and many flowers, including astibe, cotoneaster, hostas, mallow, roses, and primula.
In clay, color matters. Red clay indicates good aeration and is a looser soil that will drain better. Blue and gray clays are tighter and need to be loosened before they are capable of support growth. Soils can be loosened by working in lots of organic material or use the soil in raised beds to ensure that the soil drains better. Adding a mixture of coarse, sharp sand and crushed eggshells or powdered milk (for calcium) can also help the soil.
TIP: Susan advises, "Compost or aged manure adds vital nutrients into any soil type."
There is a reason they created sandpaper instead of clay paper - sand has a very rough texture. It is also the largest particle in soil (0.05-2 mm in diameter). It is usually light in color and dries out quickly. Basically, sandy soil is very small particles of silica and quartz, humus and a little bit of clay. The amount of humus, or natural compost, present in the soil will alter the color and the texture of the sand.
Sand is much easier to work with in comparison to clay, but does not hold moisture or nutrients well. Of all the major types, sand warms up quickest in the morning. Small plants with shallow roots will do well in this soil, including rosemary, lavender marjoram, oregano, sage, santolina, savory, thyme, coreopsis, impatiens, evening primrose, poppies, yarrow, sedums, and some dianthus.
If silt were a bear, it would be the baby bear. It is not too large or too small, but somewhere in the middle (between 0.002-0.05 mm in diameter). Silt is smooth and powdery when dry, and smooth, but not sticky, when wet. It retains both nutrients and water better than sand, but not as well as clay. This means that silt will drain better than clay does. Silt is often found in rivers because the finer particles are washed downstream. Most plants will grow in silt. If the soil becomes too compacted, it can be improved by adding organic material