Soil pH is a very important factor in plant health – if the soil is too acidic or too alkaline, plants will be unable to absorb nutrients properly, and your garden won’t grow. The degree of acidity and alkalinity is measured on a scale of 0-14, with a pH of 7 neutral, 0-7 acidic, and 7-14 alkaline.

The ideal soil pH for vegetables and lawn grasses is 6.5, just a little on the acidic side. A soil test is needed to determine the pH of your soil.

It’s important to identify the plants in your yard before attempting to adjust the pH level of your soil, since some flowers and shrubs thrive in a slightly higher or lower pH soil. If the results of a soil test indicate that the pH of your soil needs adjusting, here’s how to go about adjusting it.

Tips for Soil pH Correction

Read Label: No matter which product you choose, it’s important to follow the instructions on the package to the letter, even if you have to buy a special spreader or applicator to get it right. For example, one brand of sulfur may be more finely ground than another, and over application could damage your plants. While your soil test results will provide general guidelines about how much amendment is needed, follow the label on the particular product.

Proceed Slowly: Make one application of the product, wait at least three months, retest the pH of the soil, and reapply again if needed. It might take a year or more to get your soil on track, and overdosing can cause more harm than good.

Fall Application: For best results, incorporate pH-correcting amendments in the fall, to give them plenty of time to break down for spring planting. Many gardeners make soil testing and pH-fixing an annual fall ritual.

Plant Selection: You’ll have much better luck if you choose plants well suited to the soil you already have. It’s OK to tweak the pH a little to optimize the growing conditions, but your overall soil makeup pretty much is what it is.

How to Raise the pH in Acidic Soil?

To make soils less acidic, the common practice is to apply a material that contains some form of lime. Ground agricultural limestone is most frequently used. The finer the limestone particles, the more rapidly it becomes effective. Different soils will require a different amount of lime to adjust the soil pH value. The texture of the soil, organic matter content and the plants to be grown are all factors to consider in adjusting the pH value. For example, soils low in clay require less lime than soils high in clay to make the same pH change.

Selecting a Liming Material: Homeowners can choose from four types of ground limestone products: pulverized, granular, pelletized and hydrated. Pulverized lime is finely ground. Granular and pelletized lime are less likely to clog when spread with a fertilizer spreader over turf areas. The finer the grind of the limestone the faster it will change the soil pH value. Hydrated lime should be used with caution since it has a greater ability to neutralize soil acidity than regular limestone.

Time of Application & Lime Placement: Lime needs should be determined by a soil test. Soil samples should be taken in the fall for the succeeding year’s garden. If test results indicate a need for limestone, it can be applied in the fall or winter months. Generally, for best results, limestone should be applied two to three months prior to planting to allow time for it to neutralize the acidity.

The most important factor determining the effectiveness of lime is placement. Maximum contact of lime with the soil is essential. Most liming materials are only slightly soluble in water, so incorporation in the soil is a must for lime reaction. Even when properly mixed with the soil, lime will have little effect on pH if the soil is dry. Moisture is essential for the lime-soil reaction to occur. In the case of lawns, it can only be surface applied and watered into the soil.

Wood Ashes: Wood ashes can be used to raise the soil pH. They contain fairly high amounts of potassium & calcium, and small amounts of phosphate, boron and other elements. They are not as effective as limestone but with repeated use, they can drastically raise the pH value of a soil, especially if the soil is sandy in texture. Ashes should not come in contact with germinating seedlings or plant roots as they may cause damage. Spread a thin layer during the winter and incorporate into the soil in the spring. Check the soil pH annually especially if you use wood ashes. Avoid using large amounts of wood ashes because excessively high pH values and subsequent nutrient deficiencies may result. Coal ashes do not have any lime value and may actually be acidic dependent on the source.