So you're looking for some advice regarding feeding your azaleas. You've landed at the right place. Since the 1980's, I've grown thousands of beautiful azaleas that have put on a spectular flower show in my own landscape and in the landscapes of hundreds of clients. All-in-all, azaleas are easy to grow. That being said, depending on variety, there are specific things you'll need to consider doing in order to grow beauties that will be the envy of all the neighbors. Of these, sunlight, soil, moisture and fertilization are the keys.
Feeding azaleas isn't rocket science. That being said, too much fertilizer, or the wrong type of fertilizer, can cause serious problems with azaleas, even death. There are only a few things to consider when fertilizing azaleas. So let's get straight to the information you're looking for.
Why is soil pH important for azaleas?
Technically speaking, pH is a gauge of the hydrogen-ion concentration in the soil. But forget about all that. When growing azaleas all you need to know about soil pH is whether your soil is alkaline, nuetral or acid. Why? Because azaleas require an acid soil in order for their roots to readily absorb nutrients from soil and from applied fertilizers that are needed for long term vitality.
Soil pH is measured on a scale of 1-14, with 7 as the neutral mark. Any measurement below 7 is considered acid and anything above 7 is considered alkaline. Azaleas prefer a soil pH between 5 to 6.5 on the scale. Anything above this and azaleas can and will suffer from chlorosis (yellowing of leaves), diminished flower bud production, and overall poor health that can result in death of the plant.
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Okay, so how to determine the pH your soil? This is where you might have to become a scientist for a few minutes...but not a rocket scientist! Easy-to-use soil pH testing kits are available at most local nursery and garden centers. Or, your local Extension Service might provide soil testing services as well. Depending on the results of the soil test, you can apply certain nutrients to the soil to either raise or lower the pH as needed.
What type of fertilizer is best for azaleas?
First, for those of you who are new to gardening, here's a little info about fertilizer. Regardless of its type, any fertilizer you buy will come with information about the nutrients it contains. Prominently featured on all packages of fertilizer will be the macronutrient ratio (N-P-K), which represents the percentage the product contains by volume of these three essential plant nutrients: nitrogen (N), phosphorus (P), and potassium (K). Some specialty fertilizers will contain additional "micronutrients," such as magnesium (Mg), sulfur (S), iron (Fe), and manganese (Mn), which target other nutritional needs of specific types of plants.
When feeding azaleas, I recommend using a granular, slow-release fertilizer that contains about twice as much nitrogen as it does either phosphorus or potassium, and a micronutritent package specifically designed for acid-loving plants. These days I'm using a 12-6-6 Azalea, Camellia & Rhododendron fertilizer made by GreenView. This fertilizer uses GreenSmart: a relatively new plant feeding technology that provides azaleas with a slow-release nitrogen that comes from organic sources and all the other nutrients they need to thrive over the long term.
When is the best time to fertilize azaleas?
You'll want to feed your azaleas at least two times a year. The first feeding should be done right when the first flowers show signs of fading in spring. At this time azaleas will begin to flush new roots that will readily grab the nutrients and supply them to the rest of the plant. I usually feed my azaleas again in early to mid fall. Always follow application instructions and recommended amounts provided on the product label.
How to apply fertilizer
When fertilizing newly planted azaleas, you'll want to broadcast recommended amounts of the fertilizer on top of and just around the root ball. It's best to do so before installing mulch.
When feeding established azaleas broadcast recommended amounts of the fertilizer around the perimeter of the plant, what some call the "drip zone." If you were to dig down into the soil, this is where you'd find the feeder roots. If you have a thick layer of mulch, it's a good idea to rake it back so that the soil surface is exposed before broadcasting the fertilizer, then replacing the mulch after fertilization. This helps to ensure the fertilizer reaches the roots of the plant.
Mulching azaleas
Mulching your azaleas not only helps to insulate plant roots and conserve moisture, It also breaks down over time to provide rich organic matter that will help to feed your plants. I use a 1.5- to 2-inch layer of shredded aged wood or bark mulch or pine straw. Avoid rubber mulch and do not use a solid plastic weed blocker. If you use a weed blocker, make sure it is a porous fabric that will allow moisture and nutrients to pass through.
Watering azaleas
Newly planted azaleas will require closer attention to watering during the first year or so. In the absence of rainfall, provide only enough water to keep the rootball and surrounding area moist to a depth of at least 6 inches. Keep in mind that too much water or constantly soggy soil can cause serious health problems to young plants, such as root rot, which can cause death of the plant. If the leaves of your azaleas are turning brown or black on the tips this could be a sign of too much moisture in the soil. Established azaleas are actually quite drought tolerant and will only need supplemental water during prolonged periods of drought.
So, now you know a heck of a lot more about feedding azaleas than you knew 5 minutes ago. See what 5 minutes of your time can do to provide years of joy growing healthy plants. Give yourself a pat on the back, you deserve it, and your azaleas will appreciate it too!
