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How to Grow a Blue Hydrangea

By Jennifer Loucks ; Updated September 21, 2017

The hydrangea is a deciduous bush-type plant that is native to China, Japan and North and South America. Hydrangea plants are available in several varieties that grow in the USDA growing zones 4 through 8. The plants commonly produce blooms that are either blue, white or pink in color. The soil acidity dictates the color of hydrangea plants and can be changed manually through the application of sulfur or limestone. Prepare the soil prior to planting hydrangeas in the early summer or late fall season.

Find a location to plant the hydrangea that is full-sun to part-shade. A location that provides morning sun and afternoon shade is preferred. The soil should be fertile and well-drained.

Test the soil pH with a home test kit. The soil pH must be 5.2 to 5.5 on the pH scale in order for the hydrangea plant to produce blue flower blooms.

Add ammonium sulfate to the soil to lower the pH number and make it more acidic. Work the ammonium sulfate into the soil and allow it to rest for two weeks. Do not attempt to lower the pH more than 1.0 point per year.

Add powdered limestone to the soil to increase the pH number. Work the limestone into the soil and allow it the soil to rest for several weeks prior to planting. The application of limestone takes several months to show changes in the pH level.

Dig a hole that is the same depth as the container and slightly wider. Add compost to the hole prior to planting to increase the nutrient level and moisture retention. Set the plant in the hole and fill with a mixture of compost and soil. Gently pack in place.

Water the hydrangea plant immediately after planting. Continue to water during the growing season to keep the soil moist but not wet. Standing water around the plant will promote root rot.

Fertilize hydrangea plants one to two times a year during the summer growing season with a slow release 10-10-10 fertilizer. An application of dried manure or compost is also an appropriate fertilizer for the plant.


Things You Will Need

  • Hydrangea plants
  • pH test kit
  • Ammonium sulfate
  • Powdered limestone
  • Shovel
  • Compost
  • Water
  • 10-10-10 fertilizer


  • Lowering or raising the soil pH may take several years to reach the desired level. Test the soil pH on a yearly basis and make adjustments as needed to maintain the desired level.
  • Do not fertilize hydrangea plants after August as they begin to start the dormancy period during this time.

About the Author


Jennifer Loucks has been writing since 1998. She previously worked as a technical writer for a software development company, creating software documentation, help documents and training curriculum. She now writes hobby-based articles on cooking, gardening, sewing and running. Loucks also trains for full marathons, half-marathons and shorter distance running. She holds a Bachelor of Science in animal science and business from University of Wisconsin-River Falls.