Dolomite lime is a common garden amendment used by gardeners to adjust soil conditions for specific plants. This product is derived from crushed dolomitic limestone and serves the primary purpose of modifying the soil environment. Knowing which plants respond favorably to this treatment is important before any application, as an incorrect use can negatively affect plant health.
Understanding the Impact of Dolomite Lime on Soil Chemistry
Dolomite lime is primarily composed of calcium carbonate and magnesium carbonate, which determines its dual function in the soil. When applied, it acts as a buffering agent, reacting with acidic components to raise the soil’s pH, making it less acidic. This process is beneficial because highly acidic conditions limit the availability of many nutrients to plant roots.
The two main components, calcium (Ca) and magnesium (Mg), are also essential micronutrients supplied directly to the plants. Magnesium is necessary for photosynthesis, as it is a central atom in the chlorophyll molecule. Calcium is needed for cell wall structure and proper root tip growth.
By increasing the pH, dolomite lime reduces the presence of toxic elements like aluminum and manganese, which are harmful in strongly acidic soils. This adjustment optimizes the range for nutrient uptake, usually between pH 6.0 and 7.0, where most major nutrients are readily accessible. The requirement for dolomite lime is tied to both existing soil acidity and a potential deficiency in these two specific minerals.
High-Demand Plants That Benefit from Dolomite Lime
Many common garden plants thrive in a neutral to slightly acidic soil environment (pH 6.0 to 7.0), and these are the plants that benefit most from dolomite lime application in acidic soils. Dolomite lime is particularly advantageous for crops that have a high demand for calcium and magnesium.
Among vegetables, members of the brassica family, such as cabbage, broccoli, and cauliflower, generally prefer a pH closer to neutral. High-calcium-demanding fruiting vegetables like tomatoes and peppers also see improvement, as the added calcium helps prevent disorders like blossom end rot. Other crops that respond well include beans, peas, corn, spinach, and lettuce.
Certain ornamental plants and herbs also respond positively to dolomite lime. Examples include roses and lilacs, which prefer slightly alkaline conditions, and herbs such as lavender and sage. For these species, dolomite lime ensures the soil pH remains in a range where they can absorb necessary nutrients.
Plants That Require Acidic Conditions
Applying dolomite lime to plants that naturally require a low pH can be detrimental, potentially leading to nutrient deficiencies and plant decline. These acid-loving species are adapted to thrive in soils with a pH typically ranging from 4.0 to 5.5. The alkalinity of the lime quickly raises the pH outside of their optimal range.
When the pH is raised too high, it can induce nutrient lockout for acidophiles, preventing them from absorbing essential micronutrients like iron and manganese. This often manifests as chlorosis, a yellowing of the leaves, particularly in the newer growth. High calcium levels can also interfere with the uptake of other cations, further stressing the plant.
Examples of plants that should never receive dolomite lime include blueberries, which require a highly acidic environment for proper iron absorption. Rhododendrons, azaleas, and camellias are classic acid-loving shrubs that will suffer from over-liming. Many coniferous evergreens, such as pines and firs, also prefer a lower pH.
Determining Application Rates Through Soil Testing
Application of dolomite lime should never be based on guesswork, as over-application can cause more harm than the initial problem. The only accurate way to determine the correct dosage is by obtaining a professional soil test. This test provides the current soil pH and details the existing levels of calcium and magnesium.
Based on the soil’s current condition and the target pH, the laboratory report provides a precise lime requirement, often expressed in pounds per area. The report also includes a buffer pH value, which measures the soil’s ability to resist pH change (buffering capacity). A highly buffered soil requires a greater amount of lime to achieve the desired pH adjustment.
Once the rate is determined, the lime is typically spread evenly over the soil surface and incorporated into the top four to six inches by tilling. Dolomite lime works slowly, requiring several weeks to months to fully dissolve and neutralize soil acidity. Therefore, it is often applied in the fall or well before the spring planting season.