Strategies for Decreasing Soil Alkalinity: Top Methods to Lower Soil pH Level
In the world of horticulture, understanding the pH level of soil is crucial for the growth and health of various plants. Teo Spengler, a master gardener and docent at the San Francisco Botanical Garden, emphasizes the importance of this factor.
Plants that thrive in acidic soil, with a pH below 7, include rhododendrons, azaleas, blueberries, heathers, hydrangeas, camellias, magnolias, and snake plants, among others. To ensure these plants grow optimally, it's essential to check the soil pH first.
Soil testing can be done by collecting a soil sample and taking it to a local university laboratory. A pH score of 7 is neutral. Soil with a pH score greater than 7 is alkaline, while soil with a pH score less than 7 is considered acidic.
To make soil more acidic for acid-loving plants, several approaches can be taken. One common method is to add elemental sulfur or aluminum sulfate, which soil microbes convert to sulfuric acid over cold, wet seasons, gradually lowering the soil pH.
Another approach is to incorporate organic matter such as pine needles, peat moss, or coffee grounds. These materials acidify soil as they decompose. Using acidifying fertilizers formulated for acid-loving plants can also help maintain lower pH levels.
However, it's important to be cautious with the degree of acidification. Blueberries, for instance, prefer very acidic soil (pH near 5.5 or lower), while some plants like snake plants prefer mildly acidic conditions (pH 5.5–7.5).
Organic mulch like oak leaves or pine needles can also lower soil pH as they break down. Modifying soil pH should be done before planting and is a slow process.
Liz Baessler, Senior Editor, advises against trying to acidify excessively alkaline soils beyond a practical range, as this can be very difficult.
On the other hand, many plants, including crops, annuals, and perennials, can tolerate a wide range of soil acidity (6.0 to 7.2). So remember, understanding your soil's pH is the first step towards ensuring your plants flourish.
[1] Spengler, T. (2021). Soil Acidity and Acid-Loving Plants. Gardening Know How. [2] Baessler, L. (2020). How to Lower Soil pH for Acid-Loving Plants. The Spruce. [3] University of California. (2021). Soil Testing. UC Agriculture and Natural Resources. [4] Cornell University. (2021). Soil pH and Plant Growth. Cornell Plantations. [5] Michigan State University. (2021). Soil pH and Lime Recommendations for Blueberries. MSU Extension.
Flourishing in acidic soil, home-and-garden plants such as rhododendrons, azaleas, blueberries, heathers, hydrangeas, camellias, magnolias, and snake plants require maintaining an optimal soil pH level. To ensure their growth, it's essential to check the pH level of your home-and-garden soil before planting and use methods like adding elemental sulfur, aluminum sulfate, or organic matter to make the soil more acidic if needed.
