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How to Fertilize an Astilbe

By Jennifer Loucks ; Updated September 21, 2017

The astilbe, a perennial flower also known as false spirea, grows best in a partial to full shade gardens in USDA Hardiness zones 4 through 8. The plant varies in height from 1 to 6 feet and produces flower plumes in red, white or pink. The astilbe grows best when given proper care through fertilizer, organic matter and water applications to maintain a healthy plant.

Work 2 to 3 inches of organic compost into the garden soil at the time of planting to add a natural fertilizer and increase the soil nutrient value.

Apply a 2 to 3 inch layer of organic mulch over the soil area around the astilbe plants. Refresh the mulch each year to maintain an adequate layer. The mulch will break down and seep into the soil to provide a natural fertilizer to the astilbe plants.

Apply a 5-10-5 flower fertilizer each month during the summer to stimulate flower growth. Follow the package instructions for fertilizer application rates based on the square feet of garden space.

Apply a high-nitrogen flower fertilizer each fall after removing all spent flower blooms from the astilbe.


Things You Will Need

  • Organic compost
  • Shovel
  • Organic mulch
  • 5-10-5 fertilizer

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.