When do azaleas bloom?

The Best-selling Reblooming Azalea on the Market Today


Looking to enhance your garden year round? Encore® Azalea is the answer.

These beauties bloom and re-bloom spring, summer, and fall, bringing endless color! But, how do they do it?

Encore Azaleas have a special, multi-seasonal bloom cycle.

The bloom cycle begins in spring, along with all other azaleas. However, when other azaleas start losing their flowers for the year, Encore Azaleas are busy setting new buds for a second blooming. Before the last spring flower falls, summer flowers are ready to explode.


But they aren’t done yet, there is still another blooming cycle in fall. We’re talking about vibrant flowers three seasons a year—the show is never cancelled – even the evergreen foliage brings life to barren winter!

Encore Azalea makes a multi-season landscape a reality, offering re-blooming shrubs in 31 varieties ranging in color and size. And, these high performers are pest resistant and sun tolerant with 24 varieties that are cold hardy to zone 6.

So, bring out the lawn chair, relax and let best-selling, re-blooming Encore Azaleas be the star of your landscape!

To view the full Encore Azalea Collection, click here.

Encore Azalea is the best azalea you’ll ever plant. Encore Azaleas are the world’s best-selling re-blooming azalea with rich, colorful blooms in spring, summer and fall. Encore Azaleas have 31 varieties of bloom colors and sizes to choose from and thrive equally well in high filtered shade or sunny locations – unlike any other azalea in the world. Find a retailer near you at www.encoreazalea.com.

Gardening : How to Get Azaleas to Rebloom Year After Year

Over the years I’ve received thousands of letters from indoor plant lovers asking for advice about this problem or that, and have always tried to answer as many as questions as I can.

Now, from time to time, I’ll be answering the questions of the most general interest here in these pages, so keep those cards and letters coming and let’s get growing!

QUESTION: Recently, I received a potted azalea as a gift. Although the leaves are still green and healthy, all the beautiful red flowers dried up and fell off. I know if you plant azaleas outdoors they’ll bloom year after year, but I live in an apartment and have no outdoor area. Is it possible to get this plant to flower again inside?

ANSWER: Yes, it’s possible to get azaleas to rebloom indoors, but it’s going to take just a bit more time and effort than cultivating an ordinary foliage plant.

Advertisement

The “recipe” for nurturing any flowering perennial (azaleas, geraniums, impatiens, hibiscus, etc.) back into bloom indoors is basically the same: Once the initial “store-bought” blooms fade and die, cut the plant back about half-way so as to give it a good, vigorous head start toward its next blooming period and then–and this is the most critical component in getting a flowering plant to rebloom–put the plant in a bright sunny window.

These plants will not rebloom without lots of bright sunlight. Keep the soil slightly moist and keep the humidity high with daily mistings, feed the plant once a week with a good commercial houseplant food, and pray a little. Your azalea should bloom for you every year for years to come.

Plant Not Dead; It Just Needs Water

Q: I recently bought a piggyback plant, brought it home, and put it in a bright, southern window. One day, about three weeks later, I came home from work and discovered it had quite suddenly completely wilted and died. What do you think happened? Do you suppose the plant was sick when I bought it?

Advertisement

A: I doubt it. One of the most common complaints I hear about piggybacks (Tolmiea menziesii) is their habit of drooping and appearing to be dead. Notice, I said appearing to be dead. Actually, that wilted, droopy piggyback is not dead at all–it’s simply begging to be watered.

Piggybacks (also sometimes referred to as pick-a-backs) are very temperamental about moisture. Let them be bone dry for just two or three days and they’ll slump over every time. It’s amazing, but if you water a droopy piggyback thoroughly and then wait a few hours, it’ll pop back up as good as new.

It can’t take too many resurrections, however, so keep the soil damp and it won’t happen in the first place. And I’d move it out of that southern window when the hot, hot summer comes. Too much light and heat can hasten that droopy syndrome. Try once more–piggybacks are beautiful and not that difficult to maintain.

AzaleaEssential Southern Plant

  • Ericaceae
  • Evergreen and deciduous shrubs
  • For zones, see below
  • Filtered sunlight
  • Regular to ample water
  • Leaves are poisonous if ingested

Rhododendrons and azaleas are arguably the South’s favorite shrubs. Many people think of them as entirely different plants, but they both belong to the genus Rhododendron, which comprises more than 800 species and 10,000 named selections. Even to the untrained eye, one difference between the two groups is obvious: rhododendrons generally have much larger leaves. From a technical standpoint, rhododendron flowers are bell shaped and have ten or more stamens, while azalea blooms are typically funnel shaped and have five stamens.

RELATED:

By making their choices carefully, gardeners in almost every part of the South can enjoy some of these plants, even if that means growing them in containers. Rhododendrons generally do better in the Upper and Middle South, though a number of selections thrive in the Lower South. Azaleas, however, are more accommodating; with the necessary attention to soil, light, and proper selection, they can be grown throughout the South.

Rhododendrons and azaleas have much the same basic requirements for soil and water. They need acid, well-drained, organically enriched soil that should neither get too dry nor remain soggy. Planting in heavy clay is a no-no: root rot often ensues, indicated by yellowing, wilting foliage and collapse of the plant. Planting in limy, alkaline soil is another mistake; lack of iron quickly results in chlorosis (yellow leaves with green veins). Alkaline soil has not, however, discouraged azalea lovers in Texas and Oklahoma. The recommended practice there is to build raised beds 15–18 in. deep and fill them with a half-and-half mixture of finely milled bark and coarse sphagnum peat moss (be sure to mix the two thoroughly with water before filling the beds). Irrigating with alkaline water will slowly raise the pH; to keep it in the desired range of 5.0–6.0, prepare a mixture of 3 parts garden sulfur to 1 part iron sulfate, then apply it at the rate of 1 pound per 100 sq. ft. of garden bed. This should lower the pH by one point.

Plant azaleas and rhododendrons with the top of the root ball slightly above soil level. Don’t cultivate around these plants, as they have shallow roots. Because they absorb water through their foliage, wet both the leaves and root zone when you water. Overhead watering with sprinklers works well, but to prevent fungal diseases do this in morning so that leaves dry by afternoon. Avoid drip irrigation―it doesn’t wet the root system uniformly.

In spring, just after the blooms fade, apply mulch and fertilize with a controlled-release, acid-forming fertilizer such as cottonseed meal or commercial azalea/camellia food. Do not mulch in fall; this will hold heat in the soil and delay the onset of dormancy, increasing the chances of winter damage. And don’t fertilize before bloom―you’ll encourage leafy growth at the wrong time.

The sun tolerance of azaleas and rhododendrons varies by species and selection. In general, most types prefer the partial sun or filtered shade beneath tall trees. The east and north sides of the house are better locations than the west and south. Too much sun bleaches or burns the leaves; too little results in lanky plants that don’t bloom.

Insects and diseases seldom bother healthy, vigorous plants. However, rhododendrons growing in heavy clay often fall victim to Phytophthora, a deadly soil-borne fungus that causes dieback. Azaleas growing in full sun are often plagued by sucking insects called lace bugs. For solutions to both problems, see the Southern Living Garden Problem Solver.

The rhododendrons listed here are all evergreen; azalea species and hybrids may be evergreen or deciduous. Plant sizes vary somewhat within groups, but most individual plants are roughly equal in height and width.

Pruning rhododendrons is simple―just follow these general guidelines. Tip-pinch young plants to make them bushy; prune older, leggy plants to restore shape by cutting back to a side branch, leaf whorl, or cluster of latent buds. Do any extensive pruning in late winter or early spring. Pruning at this time will sacrifice some flower buds, but the plant’s energies will be diverted to latent growth buds, which will then be ready to push out their new growth early in the growing season. You can do some shaping while plants are in bloom; use cut branches in arrangements. To prevent seed formation, which can reduce next year’s bloom, clip or break off spent flower trusses, taking care not to damage growth buds at base of each truss.

Evergreen azaleas are dense, usually shapely plants; heading back the occasional wayward branch restores symmetry. To keep bushes compact, tip-pinch frequently, starting after flowering ends and continuing until mid-June. Prune deciduous azaleas while they are dormant and leafless. You don’t have to prune azaleas as carefully as you do rhododendrons―the leaves are fairly evenly spaced along the branches, with a bud at base of each leaf, so new growth will sprout from almost anywhere you cut (in either bare or leafy wood).

Kinds of Rhododendrons
Most people know rhododendrons as big, leathery-leafed shrubs with rounded clusters (“trusses”) of stunning white, pink, red, or purple blossoms. These are primarily hybrids of catawba rhododendron, R. catawbiense, which is native to the Appalachians. But there are also dwarfs just a few inches tall, giants that reach 40 ft. or even 80 ft. in their native Southeast Asia, and a host of species and hybrids of intermediate size. Hybrids with Asian parentage may display exotic colors of yellow, apricot, and salmon; unfortunately, plants with these colors are often less tolerant of the South’s summer heat.
The following sections place named selections in categories to help you decide whether they’re suited to your garden and how to employ them.

Vireyas for indoors and frost-free areas. The Vireya rhododendrons, from the tropics of Southeast Asia, manage nicely in frost-free and nearly frostless zones. They are also fine container plants (even indoors), so they can be grown in colder zones if brought inside for the winter. They need an especially fast-draining potting mix (many species are epiphytes in the wild); a combination of equal parts peat moss, ground bark, and perlite works well. Typically, plants flower on and off throughout the year rather than in one blooming season. They bear waxy-textured blossoms in exciting shades of yellow, gold, orange, vermilion, salmon, and pink, plus cream, white, and bicolors. Species, named hybrids, and unnamed seedlings are offered by some specialty growers.

Rhododendrons in Clay or Alkaline Soil? They don’t like it. Planting in raised beds that are 1–2 ft. above the original soil level is the simplest way to give these plants the conditions they need. Liberally mix organic material into top foot of native soil, then fill bed above it with a mixture of 50 percent organic material, 30 percent soil, 20 percent builder’s sand. This mixture will hold air and moisture while allowing excess water to drain.

When Do Azaleas Bloom – Information On Azalea Blooming Periods

It’s a real disappointment when an azalea bush doesn’t grace the spring with glorious flowers. There are myriad possible answers to the question “Why aren’t my azaleas blooming?” but with a little detective work, you should be able to figure out the reason that fits your case. Once you know the reasons your azaleas don’t flower, you can turn your attention to getting azaleas to bloom. Read on for more information about why azaleas won’t bloom and what you can do about it.

Why Aren’t My Azaleas Blooming?

Let’s start with the most common reason why at azaleas won’t bloom. It is called inappropriate pruning. Azaleas are one of those shrubs that fix buds for the next season within weeks after this year’s flowers fade. Gardeners who prune, trim or sheer azalea bushes after that period can remove all of the buds that would have turned into next spring’s flowers.

When do azaleas bloom? Generally, azalea blooming periods come in early spring and the shrubs are considered by many the queens of the spring season. This means that the time to prune them is no later than early summer. If you prune in mid-summer, autumn or winter, your pruners are the reasons that your shrubs are without flowers this year.

Other Reasons Azaleas Won’t Bloom

If you didn’t prune last year, you’ll have to look for another reason as to why your azaleas won’t bloom. First, consider whether deer or rabbits may have “pruned” the plant without your permission. If so, you may need a fence for protection.

One other alternative is frost. An untimely frost can kill the buds of a cold-sensitive azalea. Another possibility is drought or inadequate irrigation during the bud set. Be careful to water the plant well every few weeks, especially just after the azalea blooming periods are over.

Too much nitrogen fertilizer can prevent azalea blooming too. Nitrogen encourages foliage growth at the expense of flowering. Cut back on fertilizer if this sounds like you. Too little sun can also impact flowering, so check to see if the trees around the azalea shrubs are blocking rays and, if so, trim them back.

Container azaleas that fail to bloom may be root bound. Check the drainage holes to see if roots are growing out. Generally, you must move up to a bigger pot with container azalea every few years.

Getting azaleas to bloom is not too hard when you figure out the issue. Once you have solved the problem, you can look forward to your azalea blooming periods again.

Azalea Bloom Times | Early | Midseason | Late |

These charts show approximate bloom dates for a number of azaleas in central Georgia, USDA Zone 8. Azalea bloom times depend more on the weather than on day length. Thus, the actual bloom dates may vary a week or two either way depending upon the weather–a warm spring gives earlier blooms, while a cool spring gives later blooms. Similarly, they will bloom earlier in warmer zones, and later in cooler zones. Your bloom times will differ from the chart by about one week for every USDA zone.

Azaleas form flower buds during early summer if they receive adequate moisture. If they then have a period of four to eight weeks of temperatures below 50° F in the winter, they will break into bloom all at once the following spring, and stay in bloom about two weeks. Without the cold weather, they will bloom sporadically over a longer period. In USDA Zone 9 and warmer, many azaleas will bloom again in the fall.

Early Blooming Azaleas

February March 1—11—21—2—12—22—30 +++++++… Glenn Dale hybrids ++++… Kurume hybrids +++… R. austrinum ++… Hinodegiri, Snow

Midseason Blooming Azaleas

April May June —9—19—29—7—17—27—4—14—24— +++++++++++++++++++ Glenn Dale hybrids +++++++++ Kurume hybrids ++++++++++ R. austrinum +++++++++++++ Hinodegiri, Pink Pearl, Snow ++++++++ R. schlippenbachii ++++++++++++++++++++++ Gable hybrids ++++++++++++ Pericat hybrids ++++++++ R. reticulatum ++++++++ R. vaseyi ++++++++++++ Southern Indica hybrids +++++++++++++ Glacier, Delaware Valley White ++++++++++++ Knaphill, Ghent hybrids ++++++++++++ R. flammeum ++++++++++++++ R. periclymenoides +++++++++++ R. atlanticum ++++++++++++ R. alabamense ++++++++++++ R. vaseyi (in the wild) +++++++++++++++++++ North Tisbury hybrids ++++++++++++++++++++++ Satsuki hybrids +++++++++++ Robin Hill hybrids ++++++++++++ Gumpo ++++++++++++++++ R. viscosum R. cumberlandense ++++++++++++++ R. prunifolium +++ —9—19—29—7—17—27—4—14—24— April May June

Late Blooming Azaleas

July August September 2—12—22—1—9—19—29—6—16—26 ++++++++++++++++++++++++++++++++++++++++ R. prunifolium +++++++++++++++++++ R. arborescens ++++++++++++++ R. viscosum var. serrulatum

Fall for Encore Azaleas Autumn is the Time for Azalea Planting

Gardeners know fall is a great time of year to plant trees, shrubs, and flowering bulbs, but did you know autumn is an ideal time for azalea planting, too?
Encore Azaleas are the world’s best-selling reblooming azalea with blooms three times a year — spring, summer, and fall — and 31 color varieties available. Planting them in the garden before winter’s frost gives gardeners double benefits. First, you’ll enjoy their vibrant blooms until first frost and then Encore Azaleas will enjoy a period of dormancy to become established before next spring’s arrival.
Even after the fall blooms fade away on Encore Azaleas, the evergreen foliage provides a beautiful backdrop for the winter garden with lush, year-round hues of green. During the dormant period, the branches may stop growing; but underneath the soil, the roots are developing a healthy support system — fortifying the Encore Azalea to produce beautiful new growth the following spring.

Continuing Blooms. Continuous Color.

Encore Azaleas bloom in spring like traditional azaleas. Once the spring blooming concludes, new shoots begin to grow and set buds. Then blooms emerge again in mid-summer and continue in many areas until first frost. Developed by plant breeder, Robert E. “Buddy” Lee, the multi-bloomers are the product of crossing spring-blooming azaleas with a rare Taiwanese summer-blooming azalea.
Encore Azaleas are recommended for zones 7 to 10 and are especially cold and heat hardy with a higher resistance to disease and pests than traditional azaleas. University cold-hardiness trials show that 24 varieties of Encore Azalea are suitable for zones 6b and 6a.

How to Plant Encore Azaleas

Choose a location for planting that receives full sun to light, filtered shade, preferably afternoon shade. A minimum of 4 to 6 hours of direct sunlight per day is necessary for proper blooms. Select an area with good drainage, and since azaleas are acid-loving plants, having a soil sample tested is a good idea. For each azalea plant, turn the soil good and dig a hole twice as wide as it is deep. Mix some organic compost or peat moss with the soil. Remove the Encore Azalea from its container and carefully but firmly loosen the root ball. Set the plant into the prepared hole with the top of the root ball above the soil. Pull the soil around the plant, water thoroughly, and cover with mulch. Learn more about care for and planting of Encore Azaleas.

Water frequently enough to keep the roots from becoming dry after planting. Cover young azaleas with insulated covering when extreme cold weather approaches. As your Encore Azalea matures, it will need less winter care. For information on fertilizing, pruning, spacing, and simple care instructions, visit encoreazalea.com.

frequently asked questions

azaleas | related pages

Looking here is the fastest way to get an answer to your question. If you don’t see your question here, or you would like more information than you see here, consider:

  • searching the e-mail archives; or
  • sending your question to the azaleas e-mail list.

azalea questions

  1. Are azaleas the same as rhododendrons?
  2. Are azaleas hard to grow?
  3. Are azaleas poisonous?
  4. Are there good books about azaleas?
  5. Can I plant my potted gift azalea outside?
  6. Do azalea leaves show fall color?
  7. Do azaleas normally drop their leaves?
  8. How big do azaleas get?
  9. How cold-hardy/heat-hardy are azaleas?
  10. How long do azaleas live?
  11. How many different kinds of azaleas are there?
  12. How should I plant my azalea?
  13. How/when should I fertilize azaleas?
  14. How/when can I prune azaleas?
  15. How/when can I transplant azaleas?
  16. What different colors of azaleas are there?
  17. What does the Azalea Society do?
  18. What is a “bicolor”?
  19. What is a “clone”?
  20. What is a “cultivar”?
  21. What is a “cutting”?
  22. What is a “self”?
  23. What is a “species”?
  24. What is a “native azalea”?
  25. What is eating my azalea leaves?
  26. When do azaleas bloom?
  27. Where can I buy unusual azaleas?
  28. Why did my azalea die?
  29. Why did my azalea flowers go brown and mushy?
  30. Why are my azalea leaves whitish with black spots underneath?
  31. Why are my azalea leaf tips turning brown?
  32. Why are my azalea leaves yellow with green veins?
  33. Why are my azalea leaves falling off?
  34. Why do some of my azalea leaves have a thick fleshy growth on them?
  35. Why doesn’t my azalea bloom?
  36. . . .

Azaleas versus rhododendrons
Azaleas are in the genus Rhododendron. Most azaleas can be distinguished from rhododendrons by their leaves.

Azalea books
The best-known azalea reference book is Azaleas, by Fred Galle, published by Timber Press. It covers all aspects of azaleas, and describes around 6000 varieties. There are a large number of other books about azaleas.

Azalea longevity
Azaleas are long lived plants when their requirements are met. There are azaleas in Japan which are hundreds of years old, and may appear more as a small tree than a shrub, with (rarely) trunks 12 inches or more in diameter.

Azalea problems
Azaleas are generally healthy plants when their basic cultural requirements are met. However, they are subject to a number of problems caused by infectious agents, insect pests, weather and nutrition deficiencies. They usually exhibit symptoms of the problem in time to correct it.

The more common causes of the complete death of an azalea are improper planting, root problems due to poor drainage or too much watering, over-fertilizing, or bark split due to colder weather or bigger temperature swings than it could withstand (which may not show up until warm weather sets in).

Bring your dead azalea to your county agent or a master gardener, or to an Azalea Society meeting, to get post-mortem opinions as to how to prevent similar deaths.

Azalea size
Azaleas are woody shrubs which keep growing all their lives. Some varieties can get quite tall, into the tens of feet, while others remain spreading groundcovers less than 12 inches in height. Upright varieties tend to also spread out with age.

The rate of growth is a good predictor of the ultimate size. It can vary from around 2 inches to 10 inches in a season, depending upon the variety, the climate and other environmental conditions, primarily water, exposure, and nutrition.

Many of the sizes listed in books and catalogs are the so-called “10 year height”, which can be used as a point of comparison. For landscape use near the house, consider choosing some of the smaller varieties, say, those with a 10 year height of 3 to 5 feet, rather than continually pruning back the more vigorous varieties.

Azalea Society of America
The Azalea Society was founded in 1979 to promote knowledge of azaleas. It has local chapters which meet to discuss, exchange and sell azaleas, it holds an annual convention in the spring at a different city each year, and it has an excellent quarterly journal, The Azalean. Membership is $30 per year, which includes membership in one of the chapters, or you may join as an At-Large member without joining a chapter. Click Join Us to complete an application form.

Azalea toxicity
Azaleas, rhododendrons, and mountain laurel (Kalmia) are toxic when eaten by animals, and may cause abdominal and cardiovascular problems. All parts of the plants are toxic, as is honey from the flowers. Published information suggests that ingestion of 3 ml/kg of bodyweight of nectar (3/4 cup for a 125 pound person) or 0.2% of bodyweight of leaves (1/4 pound for a 125 pound person) may be toxic. However, a study of 185 cases showed only one case resulted in a hospital admission, and concluded “Ingestion of moderate amounts of azalea pose little toxic hazard.” See Steve Hennings’s web page for more details.

Blooming
Many factors affect the quantity of blooms on an azalea, beginning with heredity. Some azalea varieties are normally covered with blooms, and some are normally “shy bloomers”. Next year’s flower buds begin to form within a few months after the plant blooms. If an azalea used to bloom well, and doesn’t now, it may be due to one or more of a number of reasons:

  • pruning after the buds form, which removes the buds for next year
  • on some varieties, the buds are less cold-hardy than the plant, and may freeze, turn brown and not open
  • lack of moisture during the late spring and summer reduces bud formation – mulch helps retain moisture and also keeps the soil cool
  • less than 3 hours of sun reduces the number of buds
  • a phosphorus deficiency, characterized by dull, dark green foliage with reddening underneath, reduces the number of buds
  • poor plant nutrition reduces the number of buds

Bloom times
The bloom times of azaleas varies quite a bit, depending on the variety and on the weather. Around Washington, DC, a few varieties bloom as early as March, most bloom in April and May, some bloom in June through September, and most of the blooms appear all at once and last about two weeks.

A given variety will bloom earlier and the bloom will be more spread out in a warmer area, and will be later and more concentrated in colder areas. In the south, some spring-blooming azaleas bloom again in the fall.

Colors
Evergreen azalea colors range from white to purple to red, with no yellow azaleas and only a few orangish-red azaleas.

Deciduous azalea colors range from white to pink, and from yellow to orange to red.

Many azalea varieties also have two distinct colors in the same blossom, called a “bicolor”, and many varieties have different color patterns as well, sometimes with
differently patterned blooms on the same plant.

Cultivars
Cultivar is a shortened form of the phrase “cultivated variety”, which refers to plants propagated vegetatively, by cuttings, layering or grafting, rather than sexually by seed. A cultivar is identical to its parent.

Cultivar names may be up to three words set off by single quotes, and are properly preceded by the genus name and specific epithet in italics. For example, Rhododendron austrinum ‘Don’s Variegated’.

Cuttings
The cut off end of the stem of a plant is called a cutting. By rooting a cutting, you can make an exact copy, or “clone”, of the plant. Rooting a cutting is also called “asexual reproduction” or “cloning”.

Different kinds
There are many thousands of named varieties of azaleas. There are many more named evergreen azaleas than deciduous azaleas, perhaps because evergreen azaleas are easier to root in commercial quantities than deciduous azaleas.

Most of these named varieties are not available commercially. Typical garden centers and nurseries carry relatively few varieties, while the larger garden centers may carry as many as 50 or so varieties. Click Sources for a list of mailorder azalea nurseries with more varieties. Local plant sales are another good source for less common varieties.

Eaten leaves
Leaf damage in late spring can be feeding damage from caterpillars. You can pick them off, or use a pesticide based on a recommendation from your county extension service (take in a stem for examination).
The Rhododendron Looper is a caterpillar that looks exactly like a branch, stem, or even a stamen. It can align itself along the stem to hide, so look closely at the newest feeding damage, and see the frass (excrement) to find it, and squish it. They don’t usually kill the plant unless you have a huge population.

Leaves are also eaten by any of several members of the weevil family (most commonly the Two-banded Japanese Weevil or the Black Vine Weevil), which are difficult to control. The leaf damage looks like
notching on the outside of the leaf, all the way around the leaf, and is not very harmful to the plant. Weevils overwinter in the soil as larvae which feed on the azalea roots, which can kill the plant. Contact your local county extension service for recomended controls.

If the damage is confined to the lowest branches of small azaleas, it may be caused by rabbits. The best control is to get a cat, or to trap them. Azalea leaves and branches may also be eaten by deer.

After controlling the pests causing the damage, it may be a good idea to help the azaleas by fertilizing them (if many of the leaves are eaten off, there may not be enough left to feed the roots).

Leaf color problems
Yellow to white leaves, with black specks on the underside, may be due to azalea lacebugs. They feed from the undersides of the leaves, and suck out the chlorophyll. Check with your county extension service for recommended controls, or you can safely spray the undersides of the leaves with dilute soapy water, preferably late in the afternoon to avoid any sunburn.

Leaves with brown tips show the plant has a problem, which may be too much water, not enough water, too much fertilizer (fertilizer “burn”), or root problems.

Too much water can be due to poor drainage, or by overwatering. If an azalea sits in water for any length of time, the roots will rot and the leaf tips will turn brown as a sign of distress. Too little water also results in brown leaf tips, usually preceded or accompanied by a wilted, limp appearance.

Root problems can also show up as browned leaves. These problems are described at Leaf drop.

Fertilizing azaleas
In general, azaleas in the landscape require little or no fertilizer. Having humus (decomposed organic matter) in the soil and maintaining an organic mulch around azaleas are more important than applying chemical fertilizers, and much safer. Decomposition of the mulch normally provides the nutrients needed for the good health of the azaleas.

If chlorosis of the leaves (yellowed, with green veins) or stunted plant growth suggest there may be nutritional deficiencies, a soil test may be useful. This can usually be arranged through your county agent at little or no cost. Soil test results will show the specific amounts of nitrogen, phosphorus, potassium and various other important elements that are present in the soil. The results may be accompanied by specific fertilizer recommendations to correct any deficiencies. If not, your county agent may be able to provide specific recommendations.

Applying chemical fertilizers without knowledge of any deficiencies in your soil may not help much, and may actually harm your azaleas. As a very general rule, more azaleas are killed by kindness than by neglect.

Florist azaleas
Some varieties of evergreen azaleas are grown for sale by florists in full bloom at almost any time of the year. Try to find out the variety of your gift azalea, and look it up in a reference book or in the azalea database, to see if it is cold-hardy in your area (most of them can’t stand a frost). If it is, enjoy it inside until spring and then plant it outside in a part-sun, part-shade place in the garden (see planting azaleas). If you want to prune it, do that soon after it blooms, to avoid cutting off the buds for next year’s blooms.

While it is in the house, remove its pretty paper wrapper, and water it deeply and infrequently. A good way is to soak it in a tub of water until the bubbles stop, and then let it drain out the excess water. Do this about once a week. Exactly how often depends on its potting mix and the temperature and humidity of the room. The goal is to have moist soil, rather than having it either saturated or dry for more than a few hours at a time. Keeping it in a cool area of the house will lengthen the bloom period. Putting the pot on or near a saucer of water and gravel will raise the humidity and help it hold its leaves.

If the azalea is not cold-hardy, you can plant it outside after the last frost, still in the pot, with the rim of the pot even with the soil level, or use it as a potted plant. Remember to water it, as the roots can only get the water in the pot. Bring it back into the house during the winter as a potted plant, and put it in the coolest part of the house during the winter.

If it will be staying in the pot, fertilize it lightly every month or so through the fall, with a fertilizer low in nitrogen and high in phosphorus to promote root and bud growth without promoting plant and leaf growth. Then let it rest during the winter, but don’t forget to water it. Also, carefully remove it from the pot every six months or so to check the roots. If you see fine roots circling the root ball, put it into another pot, 2 to 4 inches wider than the old pot. Before repotting it, cut those circling roots by making top-to-bottom cuts every few inches, all the way around the root ball. A good potting mix is a 50/50 mixture of potting soil and fine pine bark.

Click indoor azalea care for more (and slightly different) information.

Growing azaleas
As described in more detail at growing azaleas, azaleas are rather easy plants to grow. If you can provide slightly acid soil with good drainage in an area with partial shade, you should be able to grow at least some of the many thousands of varieties.

Cold-hardiness is a consideration. Many varieties will grow in USDA Zone 7 to 9, with minimum winter temperatures of 0°F. Some other varieties can grow as low as Zone 4 (-30°F). Heat-hardiness is another consideration, although less is known about it. Many deciduous azalea hybrids are not tolerant of high heat for extended periods, particularly high night-time temperatures, and will slowly decline over a few years.

Leaf fall color
The leaves of some deciduous azalea varieties show attractive fall colors, ranging from yellow through crimson to purple, before dropping off in late fall.

The leaves of some evergreen azalea varieties also turn color in the fall. Some may turn and then fall off, and others retain the color through the fall and winter. They may be yellow, yellowish brown, red, dark red, or green flecked with yellowish or reddish brown.

Leaf drop
Azaleas are either evergreen or deciduous. Deciduous azaleas drop all of their leaves in the fall. In dry weather,they may drop their leaves earlier than usual. Their leaves then grow back in the spring.In warmer climates or unusually warm winters, deciduous azaleas may retain some of their leaves through the winter.

Evergreen azaleas also drop their leaves. However, they appear to be evergreen because they grow two sets of leaves each year. Their spring leaves are thinner, larger, and grow along the stems. They drop off in the fall. Their summer leaves are thicker, smaller, grow crowded at the branch ends, and remain through the winter. They remain for several years on some varieties. In colder climates or extremely cold weather, evergreen azaleas may drop most of their leaves during the winter.

Leaves that turn brown, die and drop off during the summer usually indicate a problem with the azalea. The problem may be too little water, too much water, or too much fertilizer. If the azalea was recently planted, dig it up and check the rootball for moisture, and for the general state of the roots, which should be firm and crisp. Brown and mushy roots may indicate too much water. They may also indicate one of several different fungal infections known collectively as root rot.

Leaf gall
Azaleas can get a fungal infection called leaf gall, which show as thickened fleshy growths. They first appear as shiny green lumps, which then become covered with white spores, and finally dry up and appear as much smaller brown dry lumps. The simplest control method is to pick them off the plant and put them into trash bags, preferably before they turn white and spread more spores which will appear as new galls the next spring.

Chlorosis
Yellowing of a leaf between dark green veins is called chlorosis and is usually caused by an iron deficiency. Many conditions can be responsible for an iron deficiency. Poor drainage, planting too deeply, heavy soil with poor aeration, insect or fungus damage in the root zone and lack of moisture all induce chlorosis. After these conditions are eliminated as possible causes, soil testing is in order. Chlorosis can be caused by malnutrition caused by alkalinity of the soil, potassium deficiency, calcium deficiency, iron deficiency, magnesium deficiency or too much phosphorus in the soil. Iron is most readily available in acidic soils between pH 4.5-6.0. When the soil pH is above 6.5, iron may be present in adequate amounts, but is in an unusable form, due to an excessive amount of calcium carbonate. This can occur when plants are placed too close to cement foundations or walkways.

Soil amendments that acidify the soil, such as iron sulfate or sulfur, are the best long term solution. For a quick but only temporary improvement in the appearance of the foliage, ferrous sulfate can be dissolved in water (1 ounce in 2 gallons of water) and sprinkled on the foliage. Some garden centers sell chelated iron that provides the same results. Follow the label recommendations for mixing and applying chelated iron. A combination of acidification with sulfur and iron supplements such as chelated iron or iron sulfate will usually treat this problem.

Chlorosis caused by magnesium deficiency is initially the same as iron, but progresses to form reddish purple blotches and marginal leaf necrosis (browning of leaf edges). Epsom salts are a good source of supplemental magnesium. Chlorosis can also be caused by nitrogen toxicity (usually caused by nitrate fertilizers) or other conditions that damage the roots such as root rot, severe cutting of the roots (perhaps caused by transplanting), root weevils or root death caused by extreme amounts of fertilizer.

Uniformly yellowish-green leaves is often just the need for more nitrogen. This will be more noticeable in the full sun. Some less sun tolerant varieties will always be light green in full sun.

Petal blight
Azaleas can get a fungal infection called petal blight, particularly when the weather is cool and damp as they are about to bloom. It makes the petals turn brown and mushy in a day or two after they open. It is rather easily controlled with a fungicidal spray just as the buds show color.

Planting azaleas
Azaleas prefer loose, moist, well-drained soil for their roots. If the soil is heavy, mix it with as much as 50% organic matter, such as fine pine bark or rotted leaves, before using it to plant the azalea. When choosing such soil amendments, avoid materials which may be alkaline or “hot” (containing fresh manure), such as the “mushroom compost” sold for use with perennials.

If the plant is wilting, soak it in a tub of water for a few minutes, or water it slowly and thoroughly with a hose before planting it.

If the plant is in a container, remove it. Avoid pulling it by the stems, but instead turn the container upside down and lift it off the plant. Any visible roots wrapped around the rootball will strangle the plant when they grow, instead of growing out into the soil. With a sharp knife, cut these roots by making slits about 1/2″ deep from the top to the bottom of the rootball, about every 2″ or 3″ around the rootball. Cut any matted roots off the bottom of the rootball. While it may seem harsh, cutting or untangling the roots is very important o help them become established after planting.

In good soil, dig a hole at least a few inches wider than the rootball and just as deep as the rootball, and plant the top of the rootball even with the top of the soil. Avoid disturbing the soil at the bottom of the hole. If it is disturbed or soil must be returned to the hole, tramp it firm before planting. The goal is to avoid the azalea from sinking more deeply as the soil settles. In heavy soil, plant high, with the top of the rootball several inches above the ground level, and mound the amended soil up to the rootball. In very poorly drained soil, plant on top of the soil, or in a very shallow depression.

Put the root ball into the hole, and rotate and tip the plant to its best appearance. If it was wrapped in burlap, optionally remove it. Real burlap can safely be untied and stuffed down beside the root ball, as it will rot away in a few months. You must remove plastic burlap (usually yellow or orange), as it will not rot and will impede root growth. Add soil to fill the space under and around the root ball, tamping it firmly with your fingers, and continue until the fill soil is at the same level as the top of the root ball and the surrounding soil. The goal is to avoid any airspaces without compacting it so much that water will not enter.

Mulch the plant with 2 to 4 inches of pine straw, leaves, pine bark, wood chips or whatever is available, but leave an inch around the stems without any mulch. Then water it slowly and thoroughly. Water it again the next day, and at least once a week for several weeks. The goal is to settle the soil and remove any air spaces, and to make sure the disturbed roots have ready access to water until they can grow into the surrounding soil. Remember to watch small plants for a month or more, and large plants for a year or more, and water them deeply whenever they look wilted.

Pruning azaleas
The sooner you prune the better:
– The best time to prune azaleas is in early spring, before the plant puts out new growth. Although you’ll be cutting off that year’s blooms, it gives the plant the full growing season to fill out, and time for the new growth to mature before winter.
– Pruning while they are in bloom is next best, and gives you some cut flowers, or pruning just after they bloom lets you enjoy the flowers on the plant.
– Since most azaleas start growing next year’s flower buds soon after they bloom, pruning after mid-summer cuts off next year’s bloom. Late pruning also runs the risk of the tender new growth being killed in cold climates.

Before you start, look at the plant you intend to work on, remembering that branches which are shaded out often die back and become dead wood anyway. Remove these first, as the effect of removing them may alter the way you approach pruning the rest of the branches to maintain the shape of the bush.

Use clean cutters, and keep them clean as the work progresses, using a sterilizing solution such as denatured alcohol or a 10% Chlorox solution, particularly if any cuts are in infected wood.

Older plants may have a number of tall branches which need to be eliminated. Doing that over several years reduces the shock to the plant. Remove two or three of the tallest branches, taking care to cut back to a side branch which is heading in the desired direction, and which is about 1/3rd the size of the cut branch. Cut close to that side branch, as any stubs will die back to the side branch anyway, and leave deadwood which may become infected later.

Next year take out two or three more branches using the same process, spreading the pruning over a three year cycle. This approach will result in the plant sending out new growth near the base, and lets you manage the shaping of the plant to achieve a nicely shaped bush.

Selfs
A “self” flower is a flower that is all one color. If the plant has color variations, that one color is usually the same color as the variation color on the other flowers.

A “selfed” plant is a seedling from a plant crossed with itself. This type of hybridizing is usually done to reinforce some desired characteristics of the parent, which may happen with some of the seedlings from the cross.

These are completely different uses of almost the same term, and they have nothing to do with each other.

Species
A species (singular and plural) is a member of a group of azaleas in the wild with enough characteristics in common to indicate a common descent. Seed resulting from self-pollination of a species will be true to the parent. By contrast, seed resulting from crossing different species, or hybrid azaleas, will instead grow a variety of different azaleas with characteristics ranging from those of one of the parents to the other, anything in between, and perhaps some not seen in either parent.

North America has 16 species, sometimes referred to as native azaleas, all deciduous. Japan and Asia have a number of species azaleas, many of them evergreen. Some species grow near other species and hybridize with each other. These natural hybrids have various mixtures of the characteristics of both parents.

Transplanting azaleas
The general goal when transplanting is to minimize the stress on the plant being moved. Stress is caused by leaving some of the roots behind. If possible, transplant azaleas in early fall or early spring when the weather is relatively cool, or in the winter unless the soil is frozen or soggy. If you must transplant in warm weather, choose an overcast day, or a day or so after it has rained (which cools the soil), or earlier or later in the day.

Small azaleas can be transplanted with little stress by moving a very large root ball relative to the size of the plant. That ensures that you are moving most of the roots.

For large azaleas, dig wide rather than deep to get as many roots as possible. They are generally rather shallow-rooted. The very safest approach is to dig a trench up to 12 inches deep, around the dripline of the plant. Then undercut the plant to form a cone, and start removing some of the soil an inch or so at a time, moving all around the plant, until you begin to see that you are removing roots. If possible, then get a square of burlap under the plant (tilt the plant to one side, put one edge of the burlap close to the center of the plant, wadded up so that only half of it is on the open side of the plant, then rock the plant the other way and pull the burlap through). Tie the corners of the burlap to each other across the plant. Tie the burlap as tight as possible, to keep the soil around the plant roots undisturbed. Then lift the plant by the burlap and the bottom, not by its stems.

You can reduce the stress much more by planning a year or two ahead. Moving around the plant at the drip line, cut straight down with a spade, move a few spade widths and cut again, etc., until you have cut 1/3 or 1/2 of the soil. Any cut roots will start growing on the side of the cut toward the plant. If you have the time, repeat this next year, but cut the soil you didn’t cut before. The idea is that when you finally cut it loose and move it, most of the roots will have regrown inside the soil you will be moving.

Replant the azalea following the regular planting directions. Do that as soon as possible to minimize the risk of the roots drying out. If it cannot be replanted soon, water the root ball slowly and thoroughly every day or two until you plant it.

Fall-blooming azaleas include Robin Hill, Encore

News Release Distributed 10/03/14
By Allen Owings
LSU AgCenter horticulturist

HAMMOND, La. – It’s getting to the time of year when multiseason-blooming azaleas will begin their fall floral displays. Popular fall-flowering azaleas include the Robin Hill and Encore types.

Robin Hill azaleas resulted from hybridization work conducted by Robert Gartrell of New Jersey in the 1950s and 1960s. These have large flowers on hardy plants; good form and foliage, and an intermediate growth size. Other main attributes are cold hardiness and an extended blooming season.

Most years, Robin Hill azalea varieties will bloom for six months in Louisiana. You can get two to three months of bloom in spring and another three to four months in late summer through early winter. This group includes 70 varieties with 10-12 readily available in Louisiana. Louisiana nursery growers began growing these popular azaleas in the 1980s, and they continue to be used around the state today.

Robin Hill azalea varieties for Louisiana include Conversation Piece, Watchet, Nancy of Robin Hill, White Moon, Dorothy Rees, Roddy, Gwenda, Sir Robert and Sherbrook. Flower colors vary from white to pink, blush, bicolors and more. The newest variety is Freddy, a beautiful white-flowering natural mutation of Watchet. It, however, is limited in availability for home gardeners right now. Some Robin Hill azaleas are being considered for Louisiana Super Plant status in the future.

In addition to Robin Hill azaleas, you may want to try Encore azaleas. Many of the Encore azaleas now have improved cold hardiness (normally not a problem in Louisiana), sun tolerance and lacebug resistance. Encore azaleas bloom three seasons – spring, summer and fall. New Encore varieties include Autumn Sunburst, Autumn Lily, Autumn Jewel and Autumn Ivory.

Encore azaleas were developed by Louisiana nursery grower and plant breeder Robert E. “Buddy” Lee of Independence. Lee first envisioned Encore azaleas in the early 1980s when he found a tray of azalea cuttings blooming in the summer sun at his small Louisiana azalea nursery. Inspired, he began crossing traditional spring-blooming azaleas with the rare Taiwanese summer-blooming azalea, Rhododendron oldhamii. After many years, the Encore azaleas were ready for their gardening debut.

Encore and Robin Hill azaleas are evergreen, just as most traditional azaleas. Most varieties have a slow-to-medium growth rate and reach mature heights of 3-4 feet with an equal spread. A few of the Encore varieties produce larger-growing plants. Just as with other azaleas, they prefer a partial sun to partial shade and need acidic, well-drained soil. After planting and during the establishment phase, irrigate as needed to aid in plant establishment.

Azaleas blooming more than once a year should be pruned in spring within 2-4 weeks after the bloom cycle is completed. Fertilize in spring also with a slow-release fertilizer after flowering. Mulch azalea beds with pine straw.

Azaleas need a partial sun to partial shaded planting location. Plants do best in well-drained raised landscape beds. A soil pH of 5.5 is ideal. Plants should be mulched with pine straw. Uniformity in soil moisture is important.

The unique multiseason-blooming Robin Hill and Encore azaleas are available at many Louisiana garden centers. You can see many azaleas, including both these types and other spring- and fall-flowering varieties, in the Margie Jenkins Azalea Garden at the LSU AgCenter Hammond Research Station in Hammond, Louisiana.

Intermediate-growing azaleas, like Robin Hill varieties, work well in foundation plantings with Knock Out roses, Indian hawthorn, loropetalums and other popular shrubs. They are also great for use in beds underneath trees as a companion plant with hydrangeas and native shrubs. Including small-growing trees, such as redbuds and Japanese magnolias, add appeal to an azalea planting, and Japanese maple goes great in an azalea garden as a smaller, signature, focal tree.

You can see more about work being done in landscape horticulture by visiting the LSU AgCenter Hammond Research Station website. Also, like us on Facebook. You can find an abundance of landscape information for both home gardeners and industry professionals at both sites.
Rick Bogren

Azaleas

I had always thought of azaleas as small plants until one day I visited an old Sydney garden and found myself walking through a tunnel of shrubs. Wondering what they were, I looked up and discovered azalea flowers above my head. These plants, which were decades old and had never been pruned except to create space to walk, had grown 3m or more tall.

Azaleas are evergreen shrubs in the Rhododendron genus. Most grow 1-2m tall and many are smaller. They are at their peak from late winter to spring when they are in full bloom. Azaleas flower generously and many varieties also bloom at other times of the year, a habit called ‘spot flowering’.

These plants are originally from Asia where they grow in woodlands. Today’s azaleas have come a long way from their wild relatives. They flower in many colours (including white, pink, salmon, lilac, purple, red and variegated) and in a range of shapes and sizes from large and single, to hose in hose (a form of azalea where that appears like one single flower in another), double or ruffled. Some azaleas are perfumed.

Many grown today have been bred to thrive in containers in partly shaded areas such as courtyards. For larger, stronger growers for a shrubbery, woodland garden under trees or as a hedge, seek out older varieties such as ‘Alba Magna’ (white), ‘Splendens’ (salmon), ‘Magnifica’ (purple) and ‘Alphonse Anderson’ (pink with white edge and dark pink throat) all of which have large, single flowers. These varieties also grow well as standards – that is, specimens trained with a single stem and ball of growth.

As well as these stalwarts, there are strong growers with more ornate flowers. ‘Redwing’ (red), ‘Happy Days’ (purple pink) and ‘White Bouquet’ (white) have large, ruffled flowers on a medium-sized shrub. ‘Kirin’ has small semi-double pink flowers. All grow to around 1m high.

Care and maintenance

For all their radiance, azaleas have an Achilles heel. They require the use of sprays to keep them in good health.

Their magnificent flowers are prone to a disease called petal blight, which causes the flowers to wilt as if the shrub is water stressed. As the disease progresses, the flowers become brown and remain on the plant. The disease is spread by wind and water.

The only remedy is to apply a fungicide as the buds begin to show colour in late winter or early spring and reapply fortnightly during flowering. Zaleton is registered for the control of petal blight in azaleas. Shear over plants as they finish flowering to remove any disease-infected blooms. Collect up diseased flowers and dispose of them into the garbage bin (do not compost).

Feed azaleas after they have flowered applying an azalea and camellia food (follow application instructions on the container). Azaleas also benefit from a mulch of aged cow manure.

As new growth appears, the plants are vulnerable to pest attack from either azalea lace bug or two-spotted mite (also called red spider mite). Both insect pests feed under the leaves and cause the foliage to develop unsightly mottling. They also reduce the plant’s vigour. Treat lace bug with Yates Baythroid and control two-spotted mite with Mavrik or eco-oil is an organic option.

Plants thrive in well-drained soils with added organic matter. Once established, azaleas are drought hardy but new plants and those growing in pots should receive regular watering especially when it is dry or windy.

To rejuvenate overgrown plants prune hard after flowering, cutting the bush back in stages to avoid pruning shock. Remove around a third of the plant, cutting down to the base of the stem. When regrowth is well established, prune again if temperatures are mild or wait until the following spring to continue the rejuvenation pruning.

At a glance

Plant name Azalea

Form Evergreen shrub

Size 30cm to 2m+ (depending on variety)

Features Beautiful winter to spring flowers in a wide colour range

Garden use Shade to part sun areas, containers, under trees, hedges, Japanese-style gardens, training as standards

Grow with Australian natives, camellias, mondo grass, clivia, deciduous trees

Soil Well-drained, slightly acidic (pH 5.5)

Feed Spring, after flowering

Prune Spring, after flowering

Problems Petal blight, azalea lace bug, two-spotted mite (control with registered pesticides)

Leave a Reply

Your email address will not be published. Required fields are marked *