Fertilizing Astilbe

Astilbe is a great plant that can well grow alongside a diverse range of shrubs and perennials in the shade of a deciduous tree. Native to the Far East, these perennials are a hugely popular choice amongst American gardeners for their elegance and ease of care. Although astilbes do not require much maintenance, they appreciate rich soil and thrive with a yearly feeding. 

Fertilize astilbe in the spring as new growth appears. Choose a formula rich in phosphorus to promote abundant blooming. Alternatively, you can use a balanced formula (e.g. 10-10-10) in spring and mid-summer.


How to Fertilize Astilbe

Fertilizing your astilbe is not only beneficial but very easy to do. Sprinkle a slow-release formula around the root zone in early spring and scratch the granules into the soil surface. Follow the directions on the packaging as closely as possible. 

Avoid fertilizing when the soil is dry. Water the soil generously while being mindful not to overly saturate it. When the soil is moist, the fertilizer will be able to dissolve and reach the roots without burning them. 

Best Time To Fertilize Astilbe

Most astilbes respond well to yearly fertilizer. Applying a phosphorus-rich, slow-release fertilizer during spring will be enough to support blooming and strong growth all season. You can also apply a balanced feed in mid-summer if the astilbe is growing slowly. Fertilizing it too frequently or in big doses can do more harm than good to your plant, so make sure not to overdo it.


Best Fertilizer For Astilbe

The ideal fertilizer for an astilbe plant is a slow-release, organic formula with an NPK ratio of 5-10-5 or 10-10-10. It’s important to use the recommended type because others may have too much nitrogen, promoting excess foliage growth. Another good option is to top-dress the soil with compost or well-rotted manure in the spring. In addition to feeding the soil, the top-dressing will help suppress weeds and reduce moisture loss.

Astilbe Fertilizing Tips

  • Make sure the soil is moist before applying fertilizer
  • Apply a phosphorus-rich fertilizer once per year in early spring
  • Feed again in mid-summer with a balanced formula (optional)
  • Top-dress the soil with compost in the spring


-Always wear protective gloves and a face mask when handling chemical fertilizers.

-Closely follow all directions and storage guidelines that are on the fertilizer label.

Sources: "Showy in the Shade: Astilbe and Ligularia." Minnesota State Horticultural Society. northerngardener.org

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Author Chris Link - Published 07-06-2022