8 Best Fertilizer for Azaleas | Check Before Buying!

Azaleas are flowering shrubs that can be planted at any season because of their showy, attractive flowers and evergreen leaves. They do not necessarily need fertilizer, but organic mulch can be used as a substitute. Supplementary feeding is sometimes applied.

To know more about their specifications, application rates, product dimensions, and other interesting information, read further this article!

What Are Azaleas?

Azaleas are popular flowering shrubs that belong to the genus Rhododendron known for their stunning floral displays and their adaptability to a wide variety of environmental conditions.

They are classified into two groups: evergreen and deciduous. Evergreen azaleas maintain their leaves throughout the entire year, while deciduous azaleas lose theirs in the fall season. 

Should I Fertilize My Azaleas?

You can fertilize your azaleas but not too much, as they can easily be injured by fertilizer since they grow shallow roots. Experts usually apply organic matter and mulch, but supplemental fertilization is occasionally necessary. Make sure to perform a soil test before fertilizing to know what nutrients your soil needs.

When to Fertilize Azaleas?

Fertilize azaleas right after flowering, between March to mid-May. Avoid fertilizing at the time of planting since it can dehydrate the plants and injure new root growth. Wait until the azaleas are fully established before applying fertilizer. 

How Often to Fertilize Azaleas?

Every 1 to 6 weeks, depending on the fertilizer in the spring. However, spring-flowering varieties may need an additional application in June at half the strength of the spring application.

Do not fertilize later than July 1, as the buds of the plants have already set, and their tolerance to winter temperatures may be reduced.

How Much Fertilizer to Use?

It depends on the number of azalea plants you have, the area they occupy, and the type of fertilizer you use. Do not worry, as this will be discussed in the following sections!

Organic Vs. Inorganic Fertilizers: Which One Is Better For Azaleas?

Azaleas prefer organic, slow-release fertilizers as they can benefit from the long-lasting source of nutrients since they can easily get overwhelmed when being fed, but inorganic fertilizers can still be used.

8 Best Fertilizer for Azaleas

Miracle-Gro 1000701 Pound

Type: Water-soluble powder

Active Ingredients: 30% total nitrogen, 10% available phosphate, 10% soluble potash

Features: Able to instantly feed azaleas and promote lush green foliage and beautiful abundant blooms. It is guaranteed not to burn the plants or harm other desirable plants in your garden as long as the instructions are observed. 

Application Rates:

Use the garden feeder to fill with the fertilizer directly, then spray on the plants. You can also dilute in a watering can.

1. For azaleas grown indoors: 

• Feeder: Fill up to the small end of the enclosed scoop.

• Watering Can: Mix ½ teaspoon per gallon of water, then apply every 2 weeks. 

2. For azaleas grown outdoors: 

• Feeder: Fill up to the large end of the enclosed scoop.

• Watering Can: Mix 1 ½ tablespoons per one and a half-gallons of water. Soak the soil at the base of the plants every 1 to 2 weeks. 

Product Dimensions: 3.75” (length) x 3.75” (width) x 5.75” (height), with a weight of 1.5 pounds

Fertilome Azalea, Camellia, Rhododendron Food

Type: Granules

Active Ingredients: 9% total nitrogen, 15% available phosphate, 13% soluble potash

Features: This fertilizer provides plant nutrients and trace elements, as well as fosters optimum acid-growing conditions that allow azaleas to thrive and develop. Despite being a little costly, it shows great results in terms of blooms and overall plant growth. 

Application Rates:

Incorporate the fertilizer evenly onto the soil, under the spread of the widest branches. Keep it away from the trunk. Feed once in the early spring, then another time after bloom, then a third time in the fall season for best results.

• For azaleas that are 1 to 5 feet in height: Apply ¼ to ½ cup of fertilizer to the plants, then thoroughly water.

• For azaleas that are 6 to 12 feet in height: Apply ¾ to 1 ¼ cups of fertilizer, then thoroughly water. 

Product Dimensions: 4.5” (length) x 8” (width) x 12.5” (height), with a weight of 4 pounds

Nelson Acid Loving Plant Food

Type: Dry fertilizer

Active Ingredients: 9% total nitrogen, 13% available phosphate, 11% soluble potash, 13% sulfur, 20% cottonseed meal

Features: Able to adjust soil pH levels through the use of four acidifying sources, guaranteeing that your soil will create the ideal growing environment for your azaleas. It encourages the growth of deep and dark green leaves and heavy flowering, as well as reduces the risk of root burn when applied. 

Application Rates:

Apply the product at the beginning of the spring season, then follow up every 2 months during the growing season.

• For azaleas planted in landscapes: Distribute ½ cup of the product evenly over 10 square feet of planting area, then water thoroughly. 

• For azaleas planted in containers: 

Container Size	1 gallon	5 gallons	10 gallons	15 gallons
Quantity	2 tsp	2 tbsp	¼ cup	⅜ cup

Product Dimensions: 5.91” (length) x 5.08” (width) x 3.7” (height), with a weight of 2 pounds.

Lilly Miller Rhododendron Evergreen And Azalea Food 

Type: Slow-release fertilizer

Active Ingredients: 10% total nitrogen, 5% available phosphate, 4% soluble potash

Features: Specially formulated to provide azaleas with acidic soil conditions, this plant food blends natural ingredients derived from organic sources to encourage the lush, beautiful growth of the plants. 

Application Rates:

• For a single azalea plant: Sprinkle ⅔ cup in a ring around the plant, about 6 to 12 inches from its trunk. For azaleas taller than 6 feet, sprinkle 1 cup at the drip line. Incorporate the fertilizer lightly into the soil. Make sure to water thoroughly afterwards.

• For azalea transplants: Mix 3 tablespoons of product into the soil at the bottom of the new planting hole. The plant’s roots should not directly touch the fertilizer. Water thoroughly then feed again in about 4 weeks.

Product Dimensions: 2” (length) x 11” (width) x 23” (height), with a weight of 16 pounds.

Safer Brand Azalea & Holly Restore Fertilizer

Type: Granules

Active Ingredients: 4% total nitrogen, 3% available phosphate, 3% soluble potash

Features: Formulated with soil microbes, this fertilizer can nourish and enhance the soil of your azaleas through the slow release of nutrients derived from organic material to ensure the quality of flowers and the overall healthy growth of the plants. Additionally, this product is children and pet-friendly as long as it is used as directed.

Application Rates:

Apply every 6 weeks through the growing season. Make sure to store it in a cool, dry place after use.

• For established azaleas: Feed 1 cup per foot of plant spread at the drip line. If the plant is 3 feet or wider, apply 1 ½ cups. 

• For azalea transplants: Incorporate 1 tablespoon of fertilizer per 4-inch pot or 1 cup per 16-inch pot into the soil before inserting the transplant. 

Product Dimensions: 4” (length) x 10.88” (width) x 14.5” (height), with a weight of 4.07 pounds.

Espoma Organic Holly-Tone Azalea Plant Food

Type: Granules

Active Ingredients: 4% total nitrogen, 3% available phosphate, 4% soluble potash

Features: This fertilizer is mixed with natural organics that slowly break down, providing a long-lasting source of plant nutrients for your azaleas. It is environmentally safe and approved for organic gardening. 

Application Rates:

It is recommended to wear gardening gloves when applying fertilizer.

• For established azaleas: Sprinkle 1 cup per foot of drip line diameter. Double the rate if the plant’s diameter is larger than 3 feet. Water thoroughly afterward.

• For azaleas planted in containers: Sprinkle 1 teaspoon of product for every 3 inches of pot diameter. Incorporate some of the product into the soil along the outer edge of the container, then water thoroughly.

• For azalea transplants: Remove half of the soil you’re going to place the azaleas in, then replace it with fertilizer. Soak it with water, then allow the plant to settle. 

Product Dimensions: 3.5” (length) x 5.5” (width) x 13.5” (height), with a weight of 4 pounds.

Down to Earth All Natural Acid Mix Fertilizer

Type: Dry fertilizer

Active Ingredients: 4% total nitrogen, 3% available phosphate, 6% soluble potash

Features: Blended specially for azaleas, this fertilizer can lower soil pH levels to promote lush blooms and early spring growth. It also boosts the plant’s resistance to cold temperatures and helps achieve optimal root growth.

Application Rates:

• For established azaleas in gardens and flower beds: Side dress 2 to 4 ounces of fertilizer onto the plant once a month during the growing season.

• For azaleas planted in containers: Lightly incorporate 1 to 2 tablespoons per gallon of the container into the soil surface.

• For larger-sized azaleas: Spread 1 pound per 1 inch of trunk diameter around the plant’s base outwards to its drip line. Mix it with the soil surface, then water thoroughly.

Product Dimensions: 3.8” (length) x 8.1” (width) x 10.7” (height), with a weight of 5 pounds.

Jobe’s Fertilizer Spikes

Type: Fertilizer spikes

Active Ingredients: 9% total nitrogen, 8% available phosphate, 7% soluble potash

Features: These pre-measured spikes provide your azaleas with the right dosage of nutrients, so you wouldn’t risk overfeeding or burning them. The product slowly releases nutrients so that there is no wastage or chemical runoff that could harm other plants in the vicinity. Make sure to keep out of reach of pets and children.

Application Rates: Using a hammer, drive the fertilizer spikes into the soil, making sure that they are evenly spaced around the plant. Place them directly below the end of its widest branches. The spikes should be hammered one inch below the soil surface. Afterwards, water thoroughly.

Plant Diameter (in feet)	1 to 1.5	2	3	4
Number of Spikes to Use	1	2	3	4

Product Dimensions: 6” (length) x 2.5” (width) x 9” (height), with a weight of 1 pound.

List of Sources

Azalea and Rhododendron Care and Culture – https://catalog.extension.oregonstate.edu/fs12/html

Selecting and Growing Azaleas – https://extension.uga.edu/publications/detail.html?number=B670

Azalea Planting – https://hgic.clemson.edu/factsheet/azaleas/

Growing Azaleas and Rhododendrons – https://extension.missouri.edu/publications/g6825