What Is the Proper pH to Grow Grapes?

Soil pH

• The pH levels are a scale from 0 to 14 that measures the acid content. As the pH levels increase in value, the amount of acid in the ground decreases exponentially; in other words, the lower your pH level, the higher the acidity of the soil. The acid content of the soil multiplies by 10 for each whole number; for example, the acid content for a pH level of 3.0 is 10 times higher than a pH level of 4.0 and 100 times higher than the pH level of 5.0.

Optimum pH Levels for Grapes

• Grapes grow best with a pH level of 5.3 to 6; this is a relatively low to medium acid content, when you consider that a pH level of 7 is the acid content found in pure water. The pH level of soil regulates the chemical reaction that transfers nutrients to plants. Typically, the lower the pH level the greater the ability for plans to transfer the positive atoms of nutrients, called cations, to the negative ions held in the dirt.

Optimum Soil for Grapes

• Grapes are versatile plants that will flourish in a variety of soils, but they do best in sandy soil with good drainage. Soils that are richer in clay can be adapted for grapes by adding sand or other organic matter, such as peat moss or compost, to the soil. The addition of sand can also decrease the acidity of the soil by diluting the clay.

Decreasing the pH level

• If the pH level is too high, you can decrease it by adding ground sulfur or ferrous sulfate to the soil. The proper ratio is 1 1/2 pounds per 100 square feet of soil to reduce the pH level by 0.5; for example, to reduce your pH level from 7 to 6, you would need to mix 3 pounds of sulfur with your soil.