Understanding Soil Types
A major factor in determining how well plants will grow on any site is their compatibility with the soil in which they will grow. Every species has a range of soil types in which it will flourish. When we see a plant we see the flowers and the foliage but there is a lot more going on than what we see. The real life of a plant is in its underground root system which holds the plant it in place, collects nutrients and water and stores these for future use.
Typically in modern landscaping the first approach to any new planting is to amend the soil. When landscaping with wildflowers and native grasses the approach is completely opposite to this. Instead of automatically changing the soil to accommodate the needs of plants, we select the species that have been designed by nature to thrive in the soil we have.
Wildflowers and native grasses have evolved over eons of time to prefer different soil types based on the properties of the soils they have naturally adapted to; it is very important to choose seeds to match your existing soil. To do that we need to know what type of soil is on our property.
Soil can be divided into three basic classifications: sand, loam, and clay. There is great variation within these basic groups but the following three categories will serve for the purpose of describing where a plant will or will not grow.
Sandy Soils: referred to a "light" soils, contain large sized soil particles that are loose and easy to work. These loose soils allow water to drain easily causing the soil to dry quite quickly. Sandy soils also contain high percentages of air as the grains do not sit snugly together. They are usually low in nutrients and are often more acidic than the more fertile loams and clays.
Clay Soils: commonly known as "heavy" soils, are at the opposite end of the particle size spectrum. Clay has very small, tightly packed soil particles. Clay soils are harder to work with than sands or loams because the tiny particles form strong bonds with each other. The top four inches of clay soils often dry out completely in the summer months becoming almost like concrete. However, clay soils are generally nutrient rich, have a high water-holding capacity, and can be very productive.
Loam Soils: are "intermediate" between sands and clays and are the best of both worlds. They are usually fertile, hold water well but also provide good drainage, and are easy to work with making an excellent medium for growing most plants. Many wildflowers do best in a loam soil.