Azalea Fertilizing Tips: When and How to Do It

Azaleas need the right nutrients to flourish. Are you using the right fertilizers?

For some plants, a fertilizer can make all the difference. After all, not all fertilizers are created equal. So what’s the best product, and how should it be applied to ensure the best possible outcome for your azaleas? 

Read on to find out.

Our Favorite Products

  • Miracle-Gro Miracid
  • Nelson Acid Loving Plant Food 
  • JR Peter’s Jacks Classic Acid Special Plant Food
  • Epsoma Holly Tone
  • Down to Earth All Natural Acid Mix

No matter the brand, always read the label and water thoroughly

purple and pink azalea flowers

The Ideal N-P-K Ratio

Select a general-purpose, balanced fertilizer with an NPK ratio of 15-15-15. The numbers represent the nitrogen, phosphorus, and potassium levels in the product, respectively.

Nitrogen is the most essential nutrient for your azalea. When the shrub receives the proper amount of nitrogen, it will grow faster.

Azaleas require acidic soils, with pH of 4 to 6 being the optimal range for nutrient absorption; otherwise, some nutrients are lost.

Because the goal is for the nutrients to be absorbed by the plant roots, apply it to the entire root region, which typically extends well beyond the canopy of the bush. Spread the plant food around your shrub up to 9 feet away from the trunk.

Spread the fertilizer granules evenly throughout the area, then thoroughly water it. Any granules that fall on the leaves or trunk of an azalea should be washed away.

Add Nutrients in the Spring

Before fertilizing azaleas, wait until new growth appears in the spring. The new growth will indicate that the soil temperature has risen sufficiently for the azalea to start absorbing nitrogen before flowering.

Avoid adding nutrients after midsummer because flower buds are beginning to form, and feeding the azalea will favor leaf development at the expense of blooms.

Furthermore, feeding in the middle of summer makes new growth more fragile and susceptible to frost damage. New leaves require time to mature before winter to be more resistant to cold temperatures. The earlier in the year you stop fertilizing your azaleas, the better.

Pink azaleas in full bloom garden

Additional Tips

As previously stated, I recommend fertilizing only once in the early spring. 

Never fertilize during a drought because the plant will not receive enough water.

Your azaleas may not need to be fertilized if you have rich soil. Azaleas are not aggressive feeders. Fertilizing the azalea will not necessarily benefit it if the leaves are a deep green color and the plant produces robust flowers, but it may be harmful if too much nitrogen is added to the soil.

If you notice the plant’s leaves are discolored, it could be due to a lack of nutrients, but it could also be a sign that something else is wrong.

Alaine Connolly
Alaine has been working way too hard in horticulture since 1992, beautifying golf courses, resorts, and hotels. She is a part time landscape designer who works full time caring for a 28,000 square foot public garden. At home, she maintains her own 400 square feet plot. Alaine lives in northern Illinois - zone 5b.
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