Information About Azaleas


Azaleas Are Turning Brown: What Causes Brown Azalea Blossoms

By Teo Spengler

Azalea flowers come in a variety of colors; however, brown azalea flowers are never a good sign. When fresh azalea blooms turn brown, something is definitely wrong. For information on the various reasons you might see azaleas turning brown, click this article.

Honeysuckle Azalea Care: Tips For Growing Honeysuckle Azaleas

By Mary Ellen Ellis

Growing honeysuckle azaleas is a great option for shady areas and anywhere you want to enjoy a beautiful flowering shrub with a sweet aroma. With the right sun and soil conditions, this is an easy shrub to grow. Click here for more information.

Native Azalea Shrubs – Where Do Western Azaleas Grow

By Amy Grant

Both rhododendrons and azaleas are common sights along the Pacific Coast. One of the most common varieties of these is the Western azalea plant. Click the following article to find out what a Western azalea is and tips on growing Western azalea plants.

Azalea Mulching Guidelines: What’s The Best Azalea Mulch

By Teo Spengler

Their requirements are few, but azaleas do need moist soil. Mulching azalea bushes is one way to keep the humidity in the soil, but using mulch for azaleas helps the plants in other ways too. Click here for information about the best azalea mulch, and tips on how to mulch azaleas.

Fashion Azalea Care – Learn How To Grow Fashion Azalea Shrubs

By Teo Spengler

No, ?Fashion Azalea? is not the name of a hot new designer of clothing for the stars. What is a Fashion azalea? It?s the common name of a vivid azalea cultivar that you might want to invite into your garden. It you want more Fashion azalea information, this article will help.

Wild Azalea Care – Learn How To Grow Wild Azalea Shrubs

By Mary H. Dyer, Credentialed Garden Writer

Although it is native to the southeastern United States, wild azalea grows in mild climates across much of the country. Want to learn about growing wild azaleas in your garden? Click on the following article for more information.

When Can I Transplant Azaleas: Tips On Relocating An Azalea Bush

By Liz Baessler

Azaleas are a favorite perennial for many gardeners because of their long lives and reliable flowering. Since they?re such a mainstay, it can be heartbreaking to have to get rid of them. It?s much more preferable to move them if at all possible. Learn more in this article.

Azaleas And Cold Weather: Azaleas That Grow In High Elevations

By Teo Spengler

Azaleas and cold weather can mesh if you pick the right cultivars and provide the right care. It?s also possible to find azaleas that grow in high elevations. This article has information about caring for azaleas in mountain climates and cooler regions.

Propagating Azalea Cuttings: How To Root Azalea Cuttings

By Teo Spengler

You can grow azaleas from seeds, but that?s not your best bet if you want your new plants to resemble the parent. The only way to be certain you?ll get clones of a favorite azalea is to propagate them from azalea stem cuttings. This article will help with that.

Do Azaleas Change Colors: Explanations For Azalea Color Change

By Bonnie L. Grant, Certified Urban Agriculturist

Imagine you have purchased a lovely azalea in just the color you wanted and eagerly anticipate the next season's bloom. It might come as a shock to find your azalea blooms in an entirely different color. Find out why this happens here.

Azalea Fertilizer Tips – What’s The Best Fertilizer For Azaleas

By Teo Spengler

Fertilizer for azaleas is often unnecessary unless the plants are showing signs of nutritional deficiency. It is important to recognize when to fertilize azalea plants and when it is not necessary. Click this article for azalea fertilizer tips.

Leaf Gall On Azaleas: How To Treat Azalea Leaf Gall

By Kristi Waterworth

Azaleas bring amazing beauty to the landscape, but when azalea leaf gall appears, the gentle illusion may be broken. Never fear, those galls can be destroyed with dedicated care and patience. This article provides additional information that will help.

Winter Protection For Azaleas: Caring For Azalea Shrubs In Winter

By Mary H. Dyer, Credentialed Garden Writer

Preparing azalea shrubs for winter will ensure your plants are hale and hearty when temperatures rise in spring. Read this article for tips on suitable winter protection for azaleas. Click here for more information.

Azalea Pest – Azalea Bark Scale

By Jackie Rhoades

Help! My azalea's turning black! You've been attacked by the scourge of the azalea. You've been invaded by the azalea bark scale. Read this article to learn more about this pest and how to control it.

Phytophthora Root Rot In Azaleas

By Heather Rhoades

Azaleas are often grown in the home landscape not only for their beauty, but for their hardiness. But, for as hardy as they are, phytophthora root rot can affect azalea shrubs. Click here to learn more.

Azalea Insect Problems – Lace Bug Damage To Azaleas

By Heather Rhoades

Azaleas are a popular landscaping plant due to their ease of care and their beauty. But, for all their ease, they are not without a few problems. One of those is the azalea lace bug. Learn more in this article.


Azalea Care

Azaleas (botanically Rhododendron) are the most popular flowering shrubs in this part of the country.

Exposure

Azaleas prefer cool, partially-shaded sites, such as the filtered shade of pine trees (when planted beneath hardwood trees, their shallower roots must compete for nutrients and water.) Althoughsome varieties tolerate sun better than others, all azaleas prefer an area that is not exposed to long periods of hot sun and drying winds. Azaleas planted in full sun are more susceptible to lace bugs, a common azalea pest, and early morning sun, following a hard freeze, may cause cold injury. Flowers last longer if plants are partially shaded, but heavy shade may result in poor flowering and weak growth.

Azaleas grow best in acid (pH of 4.5 to 6.0), well-drained, organic-rich soil. Before planting, have the soil tested, and adjust the pH according the test results. Azaleas are shallow-rooted plants, easily damaged by excessive soil moisture. Poorly drained sites do not receive the oxygen required for healthy growth, and may lead to root rot diseases. Amend the soil in these areas with composted pine bark, and plant the root ball higher than the surrounding ground level.

Mulching

A 2- to 3-inch layer of organic mulch is very important. It conserves soil moisture, maintains soil temperature, and helps to discourage weeds. There are many suitable materials available for mulching azaleas. Pine straw, composted pine bark, and leaves all work very well, enriching the soil with organic matter as they decompose. Keep the mulch a couple of inches away from the main stem of the plant, to keep the bark dry, and extend the area mulched beyond the outermost branches of the plant.

Watering

Azaleas are shallow-rooted plants, and require irrigation during dry periods. This is especially true when planting in the spring. Azaleas planted in warm weather and in sandy soils may require watering of the root mass twice a week during the first year.

To determine when to water, pull back a small area of mulch near the base of the plant, and check the moisture level of the root ball and of the surrounding soil. If the top few inches of soil feels dry, wet the soil deeply, to a depth of at least 6 to 8 inches. Use soaker hoses or drip irrigation to slowly water the base of the plants. Overhead irrigation may promote disease, as will waterlogged soil. It is important to reach a balance of regular, deep waterings, and good drainage, to maintain a healthy plant.

Fertilizing

Azaleas have low nutritional requirements, compared to other shrubs. A soil that is amended with organic matter prior to planting, and followed by a mulch of compost, shredded leaves, pine straw, or other organic material, will usually provide sufficient nutrients for healthy growth.

Fertilizer should only be used to correct a nutrient deficiency or increase growth rate. A nutrient deficiency will exhibit a number of symptoms, including stunted growth, small than normal leaves, light green to yellowish leaf color, and early leaf drop. Be aware that these same symptoms can be caused by other problems, such as heavily compacted soil, stress from insects, disease, or weeds, and excessively wet or dry soil. Fertilizer will not correct these problems, so it is important to diagnose the cause of the symptoms, and treat accordingly. If needed, fertilize in the spring, after the plants have finished flowering. You can use an organic fertilizer, such as Holly-tone or Plant-tone, following the directions on the label. It is recommended to have a soil test in order to determine if fertilizer will benefit your azaleas.


Pruning and caring for Azalea japonica

Pruning Azalea japonica

It isn’t necessary to prune the plant. Nonetheless, if you wish to balance the shape or reduce the size of your azalea, wait for blooming to be over.

  • Favor light and delicate pruning rather than drastic cutting back.
  • Remove wilted flowers regularly (deadheading) to spur appearance of new buds. This will also direct the plant’s energy to growing new branches.

Watering Azalea japonica

The surface-most roots of Azalea japonica are the most thirsty roots. They especially require frequent watering in spring and summer.

  • To reduce watering frequency, mulch the base of your Azalea japonica with maritime pine bark. This will retain moisture and cool the soil.
  • After a couple years, your azalea japonica will do fine without any watering, except in case of prolonged dry spells or heat waves.
  • If the water is hard in your area, do your best to recover rainwater. Indeed, hard water tends to reduce soil acid levels, which is the opposite of what Japanese azalea loves.


Fertilizing

Azaleas have low nutritional requirements compared to other shrubs. A soil amended with organic matter prior to planting followed by a mulch of compost, shredded leaves, pine straw or other organic material will usually provide sufficient nutrients for adequate growth.

Before fertilizing, have a specific reason for doing so, such as increasing growth rate or correcting a nutrient deficiency. A nutrient deficiency can be exhibited by a number of symptoms including stunted growth, smaller than normal leaves, light green to yellowish leaf color and early leaf drop. Be aware that these same symptoms can be caused by other problems such as heavily compacted soil stresses from insects, disease organisms and weeds and excessively wet or dry soil. Fertilization will not correct those problems, so be certain that you know the cause of the symptoms and treat them appropriately.

Having your soil tested is one way to determine if applying fertilizer will benefit your azaleas. Information on soil testing is available in HGIC 1652, Soil Testing.

Most fertilizer recommendations are based on nitrogen, which is an important element in plant growth and often the one that is most likely deficient in the soil. Apply 1 pound of actual nitrogen per thousand square feet of root spread area. Up to 2 pounds can be applied with a slow-release fertilizer. In the absence of a soil test fertilize azaleas lightly in the spring and early summer with a complete, extended-release, acid-forming, azalea fertilizer. Look for a fertilizer with nutrients in a ratio close to 2-1-1, such as a 10-5-4

Good quality azalea fertilizers will also contain necessary trace elements. Never fertilize azaleas in the late fall with these high nitrogen fertilizers, as this may delay dormancy and result in plant injury.

  • Lilly Miller Rhododendron, Evergreen & Azalea Food (10-5-4)
  • Lilly Miller Ultra Green Azalea, Camellia & Rhododendron Food (10-5-4),
  • Sta-Green Azalea, Camellia & Rhododendron Food (10-5-4),
  • Pennington UltraGreen Azalea, Camellia & Rhododendron Plant Food (10-6-8)
  • Vigoro Azalea, Camellia & Rhododendron Food (10-8-8),
  • Scotts Evergreen, Flowering Tree & Shrub Fertilizer (11-7-7).

Complete, acid-forming organic fertilizers are also excellent choices for use on azaleas, and these are great to mix into the soil at planting, as well as for use with spring fertilization. They are typically not as nutrient rich, and because of both the low nitrogen content and inability to burn the roots, they can be used to mix lightly into the soil in the fall at planting. Organic acid-forming fertilizer examples are:

  • Espoma Holly-Tone (4-3-4),
  • Fertrell Holly Care (4-6-4),
  • Jobe’s Organics Azalea, Camellia & Rhododendron Fertilizer (4-4-4),
  • Jobe’s Organics Holly Food (5-4-3)
  • Natural Guard & Organic Azalea, Camellia, Rhododendron Food (4-3-4)
  • Burpee Natural & Organic Azalea & Camellia & Rhododendron Plant Food 4-3-3
  • Miracle Gro Nature’s Care Evergreen & Shrub Plant Food (3-3-6)

Apply fertilizer to the azalea’s root zone area (area occupied by nutrient and water-absorbing roots) which can extend beyond the drip line or outer-most branches. According to research findings, a shrub’s roots can extend three times the distance from its center to the outermost branches. So, if the distance from the center of the azalea to the outer-most branches is 2 feet, the feeder roots can extend an additional 4 feet beyond the drip line. To visualize the area to be fertilized, imagine the azalea as the center point of a circle with a 6-foot radius (the “root radius”). Trace the outer edge of the root zone area.

Since most azalea roots are located in the top foot of soil, surface application of the fertilizer is adequate. Evenly broadcast the fertilizer with a handheld spreader or a rotary or cyclone spreader over the root zone area. Sweep any fertilizer off the branches and water afterwards to make the nutrients available to the roots.

For azaleas growing in a bed, follow the steps below to determine how much fertilizer to apply over the bed to supply 1 pound of nitrogen per 1,000 square feet. If the shrub’s root zone area is confined by a sidewalk or driveway, reduce the area to be fertilized accordingly.

  1. Measure the area of the bed, making an allowance for the roots that extend beyond the outermost branches. Let’s assume the bed is 30 feet long and 10 feet wide. The bed area (length x width) is 300 square feet.
  2. Determine how much fertilizer to apply over the bed to deliver 1 pound of nitrogen per 1,000 square feet using this equation:
100=Number of pounds of fertilizer required per 1000 square feet in order to apply 1 pound of nitrogen
%N in bag

Assuming you have a 12-6-6 fertilizer, the equation for this example would look like this:

100 = 8.33 lbs of fertilizer required per 1000 ft²
12

Since the root zone is 300 square feet, the actual amount of fertilizer to apply is calculated as follows:

Root area ft² x lbs fertilizer per 1000 ft² = fertilizer to apply over root area
1000 ft²

300 ft² x 8.33 lbs fertilizer per 1000 ft² = 2.5 lbs fertilizer to apply over root area
1000 ft²

Apply 2½ pounds or 5 cups of 12-6-6 evenly over the mulched bed.

Azaleas do not have to be routinely fertilized during the growing season. Any fertilizer application should be based on their appearance, such as leaf color, growth rate, soil test results and your objectives, such as encouraging growth or correcting a mineral deficiency.

The best time to apply fertilizer is when it will be readily absorbed by the roots of the plant and when the soil is moist, which can be any time from late spring (after new growth emerges) up to early summer. Avoid fertilizing plants stressed by drought during the summer months. Without water, plants are unable to absorb nutrients, so it is best not to fertilize if water is unavailable.


Native Azaleas for Florida and the Deep South

Particularly prominent in my childhood memories are flower-picking excursions on the first warm days of spring. Mother delighted my sisters and me when she suggested a trip into the woods to pick honeysuckle. We didn't know that they were really native azaleas, and we certainly had never heard such words as Rhododendron canescens. Nevertheless, these intoxicatingly fragrant flowers evoke fond memories every spring when they bloom in woods and landscapes throughout the South.

From the boat we see masses of native azaleas blooming along the banks of the river. Butterflies flit from flower to flower, and hummingbirds zoom about on iridescent wings, sipping the nectar. The first grunts of the alligators can be heard from deep within the swamp, and turtles abandon their sunny log perches and plop into the water as the boat approaches. High in the cypress snags osprey fledglings await their dinner. Red swamp maple is blooming, and the new golds and greens of emerging foliage reflect in the water. The fragrance of native azaleas infuses the air, the sun warms our backs, and as we glide down the river we are regaled with the magic of spring.

Florida Flame Azalea

Among the beautiful sights that we see along the river in early spring are the Florida flame azaleas or Florida azaleas (Rhododendron austrinum). Bright golden clusters of tubular flowers about 1.5 inches wide and 2 inches long radiate out in a circle from the tips of the shrubs' stems. The tube of each blossom is sometimes blushed with peach, red, or pink, and long stamens and pistils sweep out and curve gracefully upward. Sticky glanular hairs cover the flower tube.

The Florida flame azalea grows about 6 to 8 feet tall and two feet wide, though in the river bottoms where it competes for light and space, it may be rangier. It is hardy in USDA Zones 7 to 9 and is native to the Florida panhandle and a few counties in southern Georgia, Alabama, and Mississippi. It is drought tolerant once established, and is a popular landscape plant within its hardiness zone.

Pinxter Azalea

Also along the river can be seen R. canescens. Sometimes called the Florida pinxter or the Piedmont azalea, this one, too, is very fragrant. Flowers are usually pink, but may also be white. Stamens twice as long as the tube stick out from the flowers. This is the azalea that we picked as children along the creek banks in rural Mississippi. Although Mother called them honeysuckle, I know now that they are not related to the honeysuckles but were so named because of their honeysuckle-like fragrance.

Pinxter azaleas grow 8 to 12 feet tall and spread to form colonies. In Florida they are commercially exploited, and in Tennessee they are endangered. Hardy in Zones 6b to 10a, they are the most well-known native azalea of the southeastern states.

Swamp Azalea

Rhododendron viscosum is another azalea native to Florida as well as all the states that border the Gulf and Atlantic coasts from Texas to Maine. Called the clammy azalea or the swamp azalea, it is endangered in Maine, threatened in New Hampshire, and exploitably vulnerable in New York. This deciduous azalea blooms in summer with small white, funnel-shaped, clove-scented flowers. As its name suggests, this clump-forming azalea is suited to poorly-drained soils and wetland areas. Foliage is lustrous and green during the summer, but turns flame red in fall.

Chapman's Azalea

Chapman's azakea after blooming

Other Native Azaleas

Rhododendron calendulaceum (flame azalea), is also native north Florida according to the University of Florida. However, the USDA website indicates that its range stops just short of Florida. While not necessarily native to Florida, several other native azaleas may be suited to gardens in parts of Florida. These azaleas are native to states just north of Florida, and are grown throughout the southern and eastern states. These include the Alabama azalea (R. alabamense, Zones 6a to 9b): the dwarf or coastal azalea (R. atlanticum, Zones 5 to 9a) the Cumberland azalea (R. cumberlandense, Zones 5a to 8b) the pruneleaf azalea (R. prunifolium, Zones 5 to 9) the sweet or smooth azalea (R. arborescens, Zones 5-9A) pinxterbloom or pink azalea (R. periclymenoides, Zones 4 to 9) and the Oconee or piedmont azalea (R. flammeum, Zones 6a to 9b). Only R. vaseyi and R. canadense prefer a location in more northerly regions of the United States.

For identification purposes, the fifteen species of native azaleas are divided into three groups the white group, the pink group, and the orange group. Species in the white group include Rhododendron alabamense, R. arborescens, R. atlanticum, R. viscosum , and a recently discovered species that occurs only in South Carolina, called R. eastmanii. The white group also includes, R. occidentale , which occurs on the west coast . Included in the pink group are R. canadense, R. canescens, R. periclyminoides, R. prinophyllum, and R. vaseyi . The orange group includes R. austrinum, R. calendulaceum, R. cumberlandense, R. flammeum, and R. prunifolium.

Native azaleas should never be taken from native stands, for many of them are endangered. Reputable nurseries offer plants that are not collected from native stands. In the landscape, native azaleas prefer rich, moist, acidic soil in light shade. A thick mulch will help to preserve soil moisture and protect the shallow roots. Pruning is seldom necessary, and any that is needed should be done immediately after flowering since plants bloom on the previous season's growth. Plants can be propagated by seeds or by softwood cuttings.

Enhancing my article, and used with appreciation are R. viscosum by lilwren, R. canescens by violabird,

R. calendulaceum by irmaly, and R. chapmanii from Wikipedia and the University of Florida (with permission).


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