Information on Soil & Fertilizers for Blueberries

Soil pH

• The pH, or acidity level of the soil, is extremely important for growing blueberries. Blueberries thrive at their best in acidic soils, where the acidity measures between four and four and a half on the pH scale. The lower numbers are more acidic, with the higher numbers representing more basic levels. Local garden centers and extension services will provide you with soil tests to judge the acidity of your soil. You soil level will generally read higher than the recommended level; add granular sulfur to lower the number. Mix in the sulfur to the top 4 inches of soil about three months before you plant the blueberries to make sure it is fully incorporated for the blueberries.

Soil Drainage

• Blueberries also require the soil to drain well; standing water around the blueberry roots will cause rot or stunted growth. The trick is to use soil that will drain excess water quickly, but will retain moisture for a long time. Adding 4 to 7 percent organic matter, such as grass clippings or aged manure, will help the soil to drain better. For extremely loamy or clay soils, which don't drain quickly, consider planting the blueberries in raised beds about 9 inches above the rest of your garden to increase drainage with gravity.

Types of Fertilizer

• Always keep fertilizer a minimum of 6 inches away from the plants themselves to avoid burning from nutrient overload. When you plant the blueberries, mix 1/2 to 2/3 lb. of ammonium sulfate per 100 feet of land into the soil before adding the plants. After four weeks of allowing the blueberries to get established, fertilize again with 10 to 16 oz. of balanced or high-nitrogen fertilizer. Nitrogen is the most important nutrient the blueberries need. For the remainder of the lives of the blueberries, apply 11/2 lb. of ammonium sulfate or 3 lb. of balanced fertilizer every year.

How to Fertilize

• Fertilize your blueberries in early spring, before the plant's leaves or berries start to sprout. This gives the new growth an extra boost. Apply fertilizer only when the plants are dry; otherwise, fertilizer granules can stick to the stems and branches and cause burning from excessive nutrients. Whenever possible, apply fertilizer by hand to the base of the plants to avoid sprinkling the granules onto the stems and branches. Once blueberry plants are older, generally after four or five years, you can apply the fertilizer with a broadcast applicator if necessary, since older plants can better stand up to potential fertilizer damage.