Whether your soil is alkalie or acidic the only long term technique for bringing the pH close to neutral, the ideal, is to add lots of organic matter each year from now on.  As the earthworms and soil microbes chow down on that organic lunch, they will reduce the alkaline pH to about 6.8; ideal for most plants.  It will take a year for this to happen.

If You Need To Get A Change NOW

A product called garden sulfur can reduce the pH of an alkaline soil fairly quickly.

Benefits of Garden Sulfur:

• Turns hydrangeas from pink to blue
• Lowers pH of soil to its optimum range
• Promotes growth and dark greening of plants
• Won’t burn your plants because of its low salt index
• Safe to use around children and pets (not hazardous or toxic)
• When used as part of a regular fertilizer program, it can provide a season-long source of sulfur.

Directions for using Garden Sulfur

It is always recommended that you do a soil analysis to ensure the proper rate of application.

Plant Food Recommendation

Sprinkle 3 tbsp. Per 100 sq. ft. (1 tsp per plant) around the root zone. If possible, mix it in with your fertilizer and work it into the soil.

Soil Acidifier Recommendation

In the absence of a soil test, follow the rates below. Results can take up to several weeks depending on rate, soil temperature and timing of application. Reduce the rates by one-third for sandy soils and increase by one-half for clay soils. In general, the optimum range for blue hydrangeas is 5.5 – 6.0, and for blueberries it’s 4.5 – 5.0.

The chart below gives you pounds of sulfur per hundred square feet in a loamy soil it takes to change your soil to the desired pH.

Adjusting pH With Sulfur

Present pH 6.5 6 5.5 5 4.5 

8      3   4   5   6 7 

7.5                   2      3      4       5    6

7                      1       2      3       4    5

6.5                           1       2       3    4

6                                       1        2    3