Home-grown blueberries bring the taste of sunshine right into your kitchen. Well-known as wildlife attractors, blueberry bushes can also make your yard a sanctuary for birds when you grow tired of berry-picking. Success with blueberries, however, requires careful soil preparation. Blueberries thrive in strongly acid soil, and your soil may need to be amended to host them well. Aluminum sulfate is often used to create the right pH for blueberries.
The acid/alkaline balance of your soil determines how plant varieties access available nutrients. This relationship is described as pH, measuring the availability of hydrogen ions to molecules for nutrient processing. The pH scale has 14 levels, with 0 being the most acid, 14 the most alkaline and average neutral soil at 6.5 to 7.5, a pH level at which a very large number of garden plants grow. A former woodland plant, blueberry grows best in soil with moderately high acidity, or a pH of 4.5 to between 5.1 and 5.4. In more alkaline soils, blueberries develop iron chlorosis, resulting in leaf yellowing, leaf loss and failure to bud, bloom or fruit.
With time to plan ahead, you can follow testing your soil with applications of elemental sulfur at intervals of one year and six months before you plant blueberry bushes. The popularity of aluminum sulfate as a soil-acidifier is directly related to the speed with which it works. The aluminum begins acidifying soil as soon as it dissolves, with the sulfur compounds continuing the process over time. This rapid acidification is similar to that achieved by ammonium- or urea-containing soil amendments, according to Clemson University Extension.
The Argument for Aluminum Sulfate
Rapidity and a long record of successful support for blueberries make aluminum sulfate the automatic choice for home gardeners who want to amend planting soil as they plant or do so only a few days before planting blueberry bushes. Quick-acting and convenient, aluminum sulfate can also be dug in annually around existing bushes to perpetuate acidic pH levels in the soil.
The Argument Against Aluminum Sulfate
Beginning in the 1970s, doctors of both adults and children began reporting patient symptoms consistent with aluminum toxicity, among them renal failure, a neurological disorder from large accumulations of aluminum in the brain, and a variety of osteoporosis and liver and kidney disorders. While aluminum can be absorbed from drinking water and other environmental sources, the American Academy of Pediatrics observed, elevated aluminum levels had particularly harsh impacts on the smaller body-mass and rapidly growing systems of children. In addition to reduction of aluminum-based consumer goods, the AAP noted, limiting contact with aluminum compounds of all kinds improved the neurological and renal health of children. One reduction in aluminum exposure that is easy for gardeners to make is the substitution of ammonium sulfate, which produces the same dual-level reduction of pH for plants like blueberries, with fewer apparent health effects. For those continuing to use aluminum sulfate, horticulturalists caution applying no more than required amounts and washing the compound off plant leaves to prevent burning.
Your Planting Articles
- Purdue University Cooperative Extension Service: Fertilizing Blueberries
- College of Agricultural and Life Sciences, University of Idaho: Growing Blueberries in the Inland Northwest and Intermountain West
- Clemson Cooperative Extension HGIC 1650: Changing the pH of Your Soil
- University of Connecticut Soil Nutrient Analysis Laboratory: Suggested Fertilizer Practices for Blueberries
- Hemera Technologies/AbleStock.com/Getty Images