Adapted for a wide range of hardiness zones, rhododendrons are found in landscapes and gardens across a good portion of the United States.
With their clusters of showy blossoms, they have made themselves known to be a mainstay flower for bringing late spring color to gardens.
Rhododendrons require little maintenance when planted in the appropriate spot – they prefer growing sites that receive dappled shade with acidic, well-drained acidic soil that is high in humic acid.
However, to get the most out of your flower, you need to take good care of your plants.
For that reason, we are going to discuss what makes a fertilizer the best fertilizer for rhododendrons and a few of our favorite options.
So let’s get started…
Table of Contents
What is the best fertilizer for rhododendrons?
Rhododendrons are light feeders and need a well-balanced fertilizer that contains the three main nutrients: Nitrogen, Phosphorus, and Potassium. In addition, it is important to note that they do well in soils with high humic acid. Little or no fertilizer at all may be needed in these situations.
Because they love acid, if acid level is low in the soil you will need to treat them with a light fertilizer in early spring and late fall.
With that being said, be sure to test your soil levels before applying plant food.
Here is a quick preview of the top 4 types of fertilizers that we are going to take a closer look at:
- Dr. Earth Organic Acid Lovers
- Schultz Slow Release Plant Food
- Jobe’s Organics Rhododendron Fertilizer
- Espoma Organic Holly-Tone
What to look for in a good fertilizer
All plants need certain nutrients in order to grow. Some of those nutrients include nitrogen, phosphorus, potassium, calcium, sulfur, magnesium, sodium, boron, chlorine, manganese, iron, zinc, copper, molybdenum, and nickel.
Nitrogen is one of the main essential nutrients; its primary responsibility in a plant is vegetative growth.
It is used in the plant to construct amino acids which are the building blocks for protein; nitrogen is a major component of chlorophyll and helps to make the foliage green, and it is also necessary for the plant’s enzymatic reactions.
Phosphorus is a component in DNA and RNA (the genetic building blocks within plant cells) and is needed for root growth and flowering.
Potassium works more indirectly than the other two nutrients. It is not a component of any plant parts but activates many of the enzymatic reactions that occur within the plant, making it imperative for overall plant health.
Plants are continuously pulling nutrients out of the soil and oftentimes, in order to meet the plant’s need, it’s necessary to add them back to the soil in the form of fertilizers.
What Rhododendrons Need…
Rhododendrons are light feeders, meaning they need less of the essential nutrients for optimal growth compared to other plants.
In fertile soils that are high in humic acid, they may perform well enough to not need any further fertilization.
In less fertile soils though, the nutrient capacity of the soil isn’t enough to meet plant demands and rhododendrons will benefit from a light fertilizer application in late winter or early spring.
Typically ornamental flowers benefit from fertilizers higher in phosphorus than nitrogen or potassium, to sustain their prominent blossom development, but rhododendrons are slightly different in this case.
Rhododendrons do produce showy, beautiful blossoms but unlike other flowering, acid-loving plants, they do not require a fertilizer high in phosphorus; they prefer a more balanced fertilizer for strong, healthy growth.
When it comes to feeding your rhododendrons, choosing an appropriate fertilizer for plants is important to meet plant needs.
There are many fertilizers available for purchase that can be used to feed your plants; look for a well-rated product for acid-loving plants that is suitable for your gardening style.
The vast amount of options means the consumer can choose conventional or organic products, and whether the product is granular or in liquid form.
The following products are excellent options that will meet plant needs and encourage vigorous growth and plant health.
An Upclose Look At My Top Picks
Dr. Earth Organic Acid Lovers
- No GMO’s
- Pet Safe
- Specifically formulated for Rhododendrons
The first option we are going to look at is Dr. Earth Organic Acid Lovers.
This plant food is specially formulated for acid lovers, this fertilizer provides optimum levels of the plant essential nutrients, including the lesser needed micronutrients, while helping to maintain acidic soil pH levels for acid-loving plants.
The formulation of Dr. Earth Organic is 100% organic and all natural, with no GMO’s, chicken manure, or sewage sludge making it people and pet safe.
It is specially formulated with their proprietary Advanced TruBiotic — five strains of beneficial soil microbes and eighteen select strains of ecto & endo mycorrhizae – designed to increase nutrient availability while boosting plant performance and drought tolerance.
Application Tips: Follow label recommendations for application rates. Acid Lovers can be applied to the soil directly or used to make compost tea.
Schultz Rhododendron Slow Release Plant Food
- Nutrient Ratio: 14-7-7
- Slow Release
- Easy to use
- Specifically designed with Rhododendrons in mind
A slow-release, granular fertilizer, such as Schultz’s Azalea, Camellia, Rhododendron fertilizer is perfectly suited for acid-loving plants. With a 14-7-7 nutrient ratio, the product contains 14% Nitrogen (N), 7% Phosphate and 7% Potash – a proven formula for feeding acid-loving plants.
Are you always worried about overfeeding your plants? Well, no need to worry about Shultz’s Plant Food because it is a slow-release granular. That means the nutrients are released slowly into the soil.
This helps to prevent overfeeding and at the same time ensures that your plants get the right amount of food.
Nitrogen is available to the root zone for up to 3 months following application.
Application Tips: Best of all, it is super easy to use, in fact, there is no mixing is required; apply directly to soil 8 – 10” from the base of the plant per label recommendations for rhododendrons, work gently into the top ¼” of soil, and then water well.
Jobe’s Rhododendron Fertilizer
- Certified organic
- Nutrient Ratio: 5-4-3
- Apply every 2 to 4 weeks
- 10 ounces makes 30 gallons
Certified organic, this granular fertilizer is enhanced with Jobe’s Organics proprietary Biozome, a combination of healthy bacteria, mycorrhizal fungi, and Archaea.
Biozome helps create optimal soil conditions by improving soil texture, water retention, and penetration – all which promote plant growth.
Application Tips: For optimal use, feed rhododendron plants every 4 -6 weeks during their active growing season.
If you prefer a water-soluble over a granular you might want to check out Jobe’s Organic Water Soluble. The biggest difference between the two is the application timing. The water-soluble option is applied every 2 to 4 weeks.
Epsoma Holly Tone
- Enhanced with BioTone Microbes
Another organic option for acid-loving plants, Holly-Tone is rich in natural organics and enhanced with BioTone microbes – a proprietary blend of beneficial microbes proven to increase soil microbial activity and encourage nutrient uptake.
Application Tips: Used and recommended by professionals because of its proven results, mix Espoma Organic Holly-Tone into the soil around the base of the plant, at the recommended rate on the product label, to encourage healthy growth.
Holly-tone recommends plants should be fertilized using this product at the full rate once in the early spring and then again at a half rate in the fall.
Rhododendron plants are adapted for a wide range of garden conditions and add a great touch of early spring color to the landscape.
The plants prefer well-drained, acid soil that is high in humic acid and growing sites that receive some dappled shade during the day to protect their blooms from losing too much water.
Based on that, when searching for the best fertilizer for rhododendrons, look for one that is specifically formulated for acid-loving plants will help maintain the lower soil pH level that rhododendrons prefer.
To encourage and sustain their showy blossoms, feed them lightly with one of the fertilizers above that are made specifically for acid-loving plants, based upon the label recommendations.
Nurturing your rhododendrons with these conditions will help result in beautiful, strong plants that provide stunning, showy blossoms.
Now it is your turn, please share with us what you think is the best rhododendron fertilizer and any experiences you may have had in the comments section below.