Never underestimate the importance of good soil. If soil conditions are wrong, plants will not thrive. Soil health should be the first consideration when designing a new garden. Plants do not all have the same soil requirements. Find out what is typical of the native soil in your region. Then amend the soil to meet the requirements of the plants you wish to grow.
Loam is the ideal growing medium. It is composed of sand, silt, clay and humus. The goal is to create the right balance. Once we know which soil components occur naturally in our garden, we can add the others needed. The desired ratio is 60 per cent clay, 30 per cent silt and 10 percent sand. Organic matter like manure and leaf mold can be introduced each year to provide nutrients. This is the perfect growing environment for most plants. Specialty plants will require different soil ratios. Rock garden plants need larger amounts of sand. A bog garden will need more clay. Native plants will tolerate the existing soil if it has not been altered.
Clay is the finest soil particle. It is derived mainly of minerals. This is why it can become dense and hard when it dries out. Clay also has the tendency to hold too much water and become slimy. Clay soils do not drain well. You can do a simple pinch test to see if your soil contains a lot of clay. It will stay together like play dough if it is high in clay. Seek out plants that can tolerate clay, or amend the soil with as much organic matter as possible. This will also encourage microbes and earthworms to help break down the clay.
Silt is a soil particle smaller than sand but larger than clay. It is composed mainly of rock materials. This is the type of soil found at the bottom of a river bed. It is also created through friction caused by moving glaciers. Silt can be found in areas where extreme weather quickly breaks rock into fine particles. Silt soils contain a lot of good minerals but are very light. If soils are comprised of too much silt they can easily blow away in the wind, or be washed away by rain.
Some soils are naturally sandy. They drain well but do not retain moisture or nutrients. This type of soil is common in desert and coastal regions. Water activity breaks down materials like rock and shell and creates these larger soil particles. Sandy soil is great for plants that detest wet soil and obtain their nutrients in other ways. Cacti and succulents are good examples.
This is the thin layer found at the top of the soil in undisturbed areas. Humus is made up of decomposing organic materials. This can be decaying animal matter or decomposing plant materials. This layer is quickly used up by plants and will need to be mechanically replenished in the home garden.