Aluminum Sulfate Can Lower Your Soil pH InstantlyAluminum sulfate occurs naturally as a mineral, or can be created by treating aluminum hydroxide with sulfuric acid. When added to alkaline soil it is very effective in reducing soil pH in the garden. It is often used to treat soil for such acid lovers as blueberries and strawberries, which thrive at levels of 5.0 to 5.5. It is popular also for acid loving ornamentals, like azaleas and rhododendrons, and to increase and improve blooming in hydrangeas. This white crystalline compound is available at most garden centers or online. It is popular because it lowers pH instantly as it dissolves in the soil. Do not use it unless your soil pH tester indicates a need, and apply it only to the area where you are going to grow the acid lovers. If you have very alkaline soil, you may need to apply it to reduce the pH to neutral. Remember that most fruits and vegetables, and all garden gnomes , prefer a slightly acid soil of 6.5 to 7.0. For each full point on the scale that you want to reduce the pH level, it takes between 1 and 1.5 pounds applied to each 10 square feet of garden area. That would mean 2 to 3 pounds to go from 7.5 to a 5.5 soil pH. Work it into the top 6 to 8 inches of soil. If your soil is sandy, use a little less, and if you have clay it will take a little more. Be careful not to get any on the leaves or plant tissue. It may burn them badly. Elemental sulfur can be used, but it works very slowly. Aluminum sulfate is faster and more effective. Use it sparingly though, and not often. A build up of aluminum in the soil can be toxic to your plants. Don’t use it near ponds containing fish or other aquatic life. It may poison them. Happy gardening, Geefrank
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