How does the acidity of soil affect flower growth?

Soil pH can affect plant growth in several ways. Bacteria that change and release nitrogen from organic matter and some fertilizers operate best in the pH range of 5.5 to 7.0 making this the optimum pH range. Plant nutrients leach from the soil much faster at pH values below 5.5 than from soils within the 5.5 to 7.0 range. In some mineral soils aluminum can be dissolved at pH levels below 5.0 becoming toxic to plant growth. Soil pH may also affect the availability of plant nutrients. Nutrients are most available to plants in the optimum 5.5 to 7.0 range. PH can also affect the structure of the soil, especially in clay soils. In the optimum range clay soils are granular and easy to work with. However, if the soil is either extremely acid or alkaline clay, soils tend to become sticky and hard to cultivate.

A pH soil test will tell you whether your soil is within the optimum range or whether it will need to be treated to adjust the pH level. Although the optimum range is 5.5 to 7.0 some plants will grow in a more acid soil and some at a more alkaline level.

PH is not an indication of fertility, but it does affect the availability of fertilizer nutrients. The soil may contain adequate nutrients yet plant health may be limited by an unfavorable pH level. On the other hand, builder's sand, which is devoid of nutrients, may have optimum pH for plant growth.