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Guide to fertilizing azaleas

Guide to Fertilizing Azaleas


Azaleas are attractive and eye-catching shrubs used in landscapes, and are considered iconic. They make lovely additions to landscaping projects.

This shrub has captivating flowers that vary in different colors such as red, pink, white, and purple. It offers early spring blossoms that stand out because of its bright colors. In this comprehensive guide, we will walk you through the steps to effectively fertilize your azaleas.

Understanding Azaleas

guide to fertilizing azaleas

One of the best characteristics of azaleas is that they are not a hungry plant. Meaning, they do not require regular application of fertilizer unless necessary due to nutritional deficiency.

They thrive in acidic soil with a pH level between 4.5 to 6.0. When selecting a fertilizer for your azaleas, choose a product designed for acid-loving plants.

Try an azalea-specific fertilizer or one labeled for use on rhododendrons and camellias. These fertilizers typically contain a balanced mix of nutrients, including nitrogen (N), phosphorus (P), and potassium (K), as well as essential micronutrients like iron (Fe) and magnesium (Mg).

If you don’t have azaleas in your garden already, head over to our Landscape Installation Service Page. We can help.

The Best Time to Fertilize Azaleas

pink azalea
George Taber azalea-Photo by Jud McCranie.

Although azaleas do not often require fertilizer compared to other blooming shrubs, nutritional deficiency signs will tell you that it’s time for them to receive some nourishment.

If your garden soil already has organic materials, the azaleas will not require additional fertilizer because they already have the needed nutrients to grow. But, if the shrub is growing too slow, set up a fertilizing schedule.

Azaleas need fertilizer when they produce smaller leaves than normal. Also, observe if the leaves turn yellow and then drop early. Other than the leaves, if the tips of the branch are dead, it means they are suffering from a phosphorus deficiency.

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So, if the symptoms of nutrient deficiency are very noticeable, a fertilizer is a great help!

Plan to fertilize your azaleas in early spring, just before or as new growth begins. Avoid fertilizing in late summer or fall, as this will stimulate new growth that may be susceptible to winter damage. For established azaleas, a second application of fertilizer can be applied in late spring or early summer, following the manufacturer’s recommended guidelines for frequency and dosage.

Keep our Flower Bed Cleanup Service in mind at the start of a new season. We love helping our clients get their flower beds back in shape.

test soil before planting azaleas
Test soil before planting and fertilizing azaleas.

Feeding Azaleas

If you are not sure about the type of fertilizer that azaleas require, perform a soil test. If not, consider a balanced fertilizer including 15-15-15. These numbers refer to the nitrogen, potassium, and phosphorus proportionate amounts.

Typically, nitrogen is what azaleas most likely need. This nutrient boosts the plant to grow faster. To help the shrubs absorb the fertilizer effectively, spread it all over the entire root area.

To learn more about fertilizing flowers, read this publication published by the University of Connecticut, “Suggested Fertilizer Practices for Flowers.”

Organic Fertilizer

organic mulch
Organic mulch is a great way to fertilize azaleas.

If you prefer organic options for fertilizing your azaleas, consider using natural amendments like compost, coffee grounds, or well-rotted manure.

These organic materials will not only provide essential nutrients to your azaleas but also improve soil structure and microbial activity.

Apply organic fertilizers in early spring or fall to supplement the nutrient requirements of your azaleas in a sustainable and eco-friendly manner.

  • Compost: Apply a layer of well-rotted compost around the base of the plant annually.
  • Coffee grounds: Sprinkle used coffee grounds around the plant to add nitrogen and increase soil acidity.
  • Pine needles: Use as mulch to gradually increase soil acidity.
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How to Apply Fertilizer

Proper application ensures your azaleas receive the nutrients they need without risking damage:

  1. Water the plant thoroughly before fertilizing.
  2. Spread the fertilizer evenly around the drip line of the plant, avoiding the base of the stem.
  3. Use the amount recommended on the product label based on the size of your azalea.
  4. Lightly scratch the fertilizer into the top inch of soil.
  5. Water again after application to help distribute the nutrients.

Signs of Over-fertilization

Be cautious not to over-fertilize, as this can harm your azaleas. Watch for these signs:

  • Leaf burn or browning edges
  • Stunted growth
  • Wilting despite adequate watering

If you notice these symptoms, flush the soil with water and hold off on fertilizing for the rest of the season.

Additional Azalea Feeding Tips

To give you more valuable ideas on taking care of your azalea shrubs through fertilizing, consider the following tips.

  • Do not fertilize during the drought or when azalea roots cannot access sufficient water.
  • Fertilize only when azaleas show some signs of nutrient deficiency.
  • When using fresh woodchips or sawdust, it is necessary to fertilize your azaleas.
  • Soil pH: Azaleas thrive in acidic soil with a pH between 4.5 and 6.0. Test your soil and adjust if necessary.
  • Container plants: Fertilize more frequently, about every 2-4 weeks during the growing season.
  • Established plants: May require less frequent fertilization than younger or newly planted azaleas.


fertilize azaleas
Azalea photo by Jim Evans.

Wrapping Up

With proper care and attention to their fertilization needs, your azaleas will reward you with a spectacular display of color.

If you follow the above guidelines, you’ll never go wrong in growing your azalea shrubs. Sit back and  enjoy its blossoms!


George Taber azalea photo retrieved from Wikipedia. https://en.wikipedia.org/wiki/Azalea#/media/File:George_Taber_azalea.jpg

Pink azalea photo retrieved from Wikipedia. https://en.wikipedia.org/wiki/Azalea#/media/File:Azalea,_a_member_of_the_genus_Rhododendron.jpg

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