Types of soil


The soil is the basis for the growth of plants. Soil consists of solid particles that hold air and water between them. These solid particles can differ widely in size. The type of soil, its structure and its nutrients play a major role in the vitality displayed by flower bulbs and other plants. Although most plants and flower bulbs can grow anywhere, they will grow better in one type of soil than in another. The type of soil and its particular characteristics are important points of departure for drawing up a planting plan.

Every type of soil used for planting needs to satisfy the following criteria:
- Proper structure
- Good drainage
- Free of pathogens
- Sufficiently low salt level (EC)
- A pH (degree of acidity) preferably between 5.5 and 7 (although there are some exceptions)

A brief comparison of the three most commonly occurring types of soil and their suitability for flower bulbs is a handy tool for determining whether the type of soil in a certain location is suitable for planting flower bulbs there.

- Clay
Clay soil is made up of very small particles (< 0.002 mm) that are packed tightly together. This is what makes clay soils “heavy” and gives them such a dense structure. Clay soils, as compared to sandy soils, are poorly drained. During dry periods, they retain water much longer. In wet periods, however, plants will drown faster here. If organic material such as compost is added to a clay soil, the upper layer will remain lighter and contain more air, therefore giving the roots of plants and flower bulbs access to a sufficient amount of oxygen. A lack of oxygen will suffocate the roots and will lead to flower bulbs that fail to emerge and plants that wither and die. Clay soils do not erode as quickly as sandy soils so they retain nutrients better and are generally rich in nutrients.

- Sand
Sandy soil is made up of large particles that are piled loosely against one another. Plants in sandy soil almost never lack oxygen, but drying out can be a problem. This is why it is important to work a substantial amount of organic material into the soil before planting and to provide water frequently during a dry period. But watering also washes nutrients from the soil. For the good growth of plants and flower bulbs that will be left undisturbed for several years, it would be advisable to provide fertiliser at least every spring. Plants undergoing considerable growth will also need a little more fertiliser in May and June.

- Peat
Peat is a type of soil that does not consist of granules but of compressed remains of plants. Over many years, dying plants filled in swamps with a layer of their partially decomposed remains to create peat. We also find this type of soil in former swampy areas. Peat retains water and acts as a sponge. Peat soils are thus boggy soils. If you want to use an area with a peat soil for planting, you will first have to lower the groundwater level. If you let peat dry out too much, however, it will no longer absorb water. People in the Middle Ages started digging peat and drying it for turf. Plants with deep roots are generally less adversely affected by the sponginess of peat. Plants with shallow roots such as flower bulbs will have a difficult time during wet and dry periods.