Do Bean Plants Grow Faster in Different pH Levels?

Soil and pH

• When we talk about the pH of soil, what we are really referring to is its acidity or alkalinity. A pH of about 6.0 or lower is acidic, and a pH of 7.5 or higher is alkaline. The range in between is neutral. Most lawn plants and garden vegetables grow best with a pH that is neutral to slightly acidic.

Beans

• Bean plants are fairly tolerant of a wide pH range, and grow reasonably well with a pH anywhere between 5.5 and 7.0. They will grow best and produce a better crop, however, with a pH between 6.0 and 6.8, which is sightly acidic.

Raising pH

• Acidic soil is a common problem in areas across the United States. If your soil's pH is below the range that beans prefer, you can raise it by adding lime to your soil. Lime is available in a number of forms, the most common of which are agricultural lime and dolomite. A number of alternative lime sources are also available, including wood ash, crushed eggshells and oyster shells. The key ingredient in each of these materials is calcium carbonate, which raises pH by neutralizing acid.

Lowering pH

• Lowering pH is a little more difficult than raising it, and the results are often temporary, which means if you have alkaline soil you may need to fix the problem again after a few years. Sulfur is used in various forms to lower soil pH, and two of the most common are iron sulfate and elemental sulfur. Iron sulfate acts quickly, and often changes pH within 3 or 4 weeks. Elemental sulfur alters pH over time, and should be applied the year before you intend to grow beans.

Soil Testing

• If you don't know the pH of your soil, you can find out by obtaining a soil test kit from your local university cooperative extension office. A thorough list of university extensions and their locations is available on the US Department of Agriculture website. Test results generally include pH levels and recommendations for amending your soil.