Summary: Azalea plants are excellent and brilliant landscape plants and growing azaleas is not difficult – easy grow, propagate and transplant.
Question: We have heard azalea plants make good plants for use in our landscape to get started with some basic planting. How difficult are azaleas to grow and care for? Marisa, Corvallis, Oregon
Answer: Marisa, azalea plants are excellent plants for the landscape.
Many people wrinkle their forehead and scratch their head wondering what plants to choose for their basic garden plantings? Take my advice: consider first, the azaleas.
Out of flower azaleas remain extremely attractive and in full bloom these flowering shrubs are absolutely gorgeous. Besides that, they’re:
- Easy to care for
- Easy to propagate
- Easy to transplant
All pro and no con!
In our garden beds, azaleas have gradually taken over more and more of the available space, not because we planned it that way but because they proved so completely satisfactory that we wanted larger and larger plantings of them.
They seemed to offer everything we wanted in spring blooming, all-year-round-attractive plants, and so we kept buying and propagating more. They’ve become the feature attraction of our garden.
Two Kinds Of Azalea Bushes
Azaleas are of two kinds, deciduous azaleas and evergreen azaleas.
Although in the colder parts of the country the evergreen varieties lose at least part of their foliage.
Personally, I prefer these so-called evergreen kinds because…
- They include a much wider color range
- They are more compact growing
- Generally are easier to grow and to propagate
Plus, I believe most beginners would do well to start with the evergreen azaleas.
Azalea Mollis is the most popular of the deciduous shrub type and would be a good type to try next, followed by some of the less common deciduous species and varieties.
The evergreen Kurume and Kaempferi varieties make up our own collection, which ranges in color from pure white to deepest red.
We found it easy to work out effective color schemes with these plants and have never been confronted by problems of clashing colors.
We have used them grouped together for mass effect and have found them wonderfully useful for filling in around larger shrubs like rhododendrons and camellias.
There seems to be no limit, in fact, to the uses to which azalea plants can be put.
Plant Azaleas depending on the variety and type in USDA hardiness zones 4 – 9.
How To Care For An Azalea Bush
The cultural requirements of azaleas are simple but specific – they’re easy to provide but they must be provided.
All azaleas must have an acid soil pH between 4.5 – 6.0 and their root system must have good drainage so plant azaleas a well-drained soil.
In an alkaline soil they exhibit yellow leaves for want of iron and in a waterlogged soil, their roots suffocate for want of air.
A woodsy soil containing plenty of organic matter is ideal – providing it’s acid and well drained.
If your garden soil isn’t of that quality you can make it so by mixing in generous amounts of peat-moss before planting.
Most Azalea bushes do not do well in full sun, these acid-loving plants do best in partial sun.
How Should You Prune Azaleas?
Cut out and remove dead, dying or diseased branches. In general, Azaleas need little pruning but it is often advisable to remove a few twigs here and there to help force out thick new growth.
Mulching Azalea Bushes
Since azaleas have a shallow root system, the soil around them should never be cultivated.
In fact, cultivation will do much more harm than good. Hence, mulching is strongly recommended.
A mulch of oak leaves, pine bark, pine needles or peatmoss not only eliminates cultivation and weeding but, which is equally important.
Mulch protects the shallow roots that are just below the surface from heat during summer and from cold during winter. If you mulch with:
- Peat moss, a 2″-inch mulch is about right
- Pine needles, it can be somewhat deeper
- Oak leaves it can be 6 inches or more
All of course depending on the size of the plants.
Azalea plants cannot stand a waterlogged soil. However, the root ball must have sufficient water at all times to do well.
Insufficient water during summer dry spells, in fact, is the most common reason for their unsatisfactory performance. Using a soaker hose is a good watering option for azaleas.
Azaleas will need watering sooner than deeper rooted trees, shrubs and perennials, and you’ll do well to give them a drink as soon as the upper two or three inches of the soil begins to dry out.
If your plants are mulched, however, you’ll find the soil surface remains moist much longer than if it isn’t.
Azalea Plant Care: Tips For Feeding And Fertilizing Azaleas
When do you fertilize azaleas? In reasonably good soil, azaleas do not need feeding, but in soils that are known to be deficient in plant nutrients, they should be fed in moderation once or twice a year.
A commercial fertilizer prepared specially for azaleas, rhododendrons, camellias and other acid-loving plants, or an acid organic material like cottonseed meal, is recommended for this purpose.
Fertilizing with ammonium sulfate will gradually acidify the soil and furnish nitrogen. If the foliage of the azaleas remains yellowish during the summer use a little chelated iron or a fertilizer containing it.
If this is not available use a little aluminum sulfate around the plants.
Azalea petal blight seems to be the most serious of the few diseases that trouble azaleas, but this can be readily controlled with fungicides.
Lace bug is apparently the only insect pest that sometimes becomes a menace, but it can be quickly eradicated by a few sprayings with malathion or natural neem oil insecticide sprays or other pesticides/insecticides.
Selecting Azaleas: Go Evergreen And Start Small
In regards to varieties of evergreen azaleas to start with, I’d say they’re all beautiful and no matter which you choose you’ll be satisfied if not altogether thrilled.
If you’d like to start off with a fair selection of varieties but don’t want to spend too much money, here’s a tip: buy small plants.
Even 6-inch-high plants of many varieties will flower the first year after planting and, if conditions are right, they’ll soon make bushy little plants that will dazzle you with their brilliance.
Most of these evergreen azaleas are small plants and never become more than about 3 feet high, though some do eventually get to be 5 or 6 feet high with equal spread.
Select hardy varieties and plant them in sheltered locations. Prune away dead branches in early spring. After blooming, as the new branches develop, pinch any long growths to shape the plants. Cease pruning about mid-July.
Any of them can be potted up while still small and brought indoors in late fall for forcing during winter. As potted plants they’re sure to thrill you and will make wonderful gifts!
Azaleas Plants For All Climate Gardens and Patios
Few climates rule out azaleas and rhododendron plants completely. You’ll find iron-clad hardy rhododendrons that will take -20° degrees Fahrenheit winters; some of the deciduous azaleas stand up to -30° degrees Fahrenheit winters.
Azalea breeders have developed evergreen hybrids for -15 ° winters and others breeders continue to develop strains for hot summer conditions.
Azaleas also do well growing in pots and tubs making them useful as patio plants.
The fact that you can protect container plants winter and given special attention in summer makes azaleas all-climate plants.
Growing Azaleas Bushes In Pots Using Soil Mixes
Since the plants are shallow rooted, there’s no need to dig a deep planting area. You only need an 18″-inch deep bed of a peat sand mixture. Of course, when growing in pots and containers this special “soil” is ideal.
As stated above “In reasonably good soil, azaleas do not need feeding.” But when using such mixes, a consistent fertilizing program is necessary. The ideal food for azaleas and rhododendrons is one designed specifically for the plant. Ask at your local garden center.
Used frequently, liquid azalea fertilizer works great and produces the best growth.
Start fertilizing at the end of spring after the plants have bloomed and continued to August or September.
Water to keep mulch and soil moist at all times but never soggy. If drainage is taken care of the peat moss-sand mixture is difficult to water log.
During the dry season, hose off the foliage regularly to improve the appearance of their shiny leaves and to discourage red spider.
Pests on foliage – Seasonally look at preventing attacks of the most common azalea and rhododendron pests scale, red spider, white fly, and lace bug.
Root weevils – In the grub stage, root weevils feed on the roots of the plants; in the adult stage they feed on leaves.
My Azaleas Do Not Grow – Why?
Question: Although I feed and water my azaleas well, they do not grow. They get plenty of shade from large shrubs that grow just behind them.
Answer: The trouble, no doubt, is caused by the roots of the neighboring shrubs, which use most of the food and moisture available in the soil, leaving little for the azaleas. I would suggest that you create some type of root barrier vertically in a narrow, 20-inch-deep trench in front of the shrubs. This will keep the roots of the shrubs from reaching into the azalea bed.
The Azalea Lace Bug Pests
Although we find lace bugs commonly present these small insects show a preference for certain plants. Among the more troublesome we see the rhododendrons, mountain laurel, azaleas, and Japanese andromeda attacked.
The foliage may become badly discolored and the plants seriously injured by heavy infestations, so knowledge of these lace bugs and their habits prove useful.
On the rich, green leaves of such evergreen shrubs as mountain laurel and rhododendron, a yellowish mottling of the upper surface may become conspicuously noticeable.
As the insect population increases during the Summer, entire leaves may become whitened and, in extreme cases, the injured leaves may curl, turn brown and even drop prematurely. Often an entire plant looks dull and unhealthy and lacks the normal, glossy appearance characteristic of such broad-leaved evergreens.
On closer study, individual, damaged leaves will often have from a few to many adult and immature lace bugs on the lower surface. That side of such leaves will be more or less thickly dotted with varnish-like spots of lace bug excrement. Usually the insects remain on the lower leaf surface which shelters and protects them.
Both young and adults forms have sucking mouth parts. They insert their stylets into the leaf and suck out the contents of the leaf cells. This kills the cells and results in the discoloration of the tissues, which is apparent on the upper leaf surface.
Azalea Lace Bug
Their distinctive form makes the azalea lace bug easily recognizable.
However, small size makes it almost imperative to use some magnifying instrument to really appreciate their appearance in detail. For this purpose, a ten-power, hand lens works fine.
The adults are of such smallness that they are measured in millimeters. The shortest of the three herein considered is the rhododendron lace bug which may be only 3.3 mm. long, while the largest is the andromeda lace bug which may be as much as 4 mm. long.
Since three millimeters is only about 1/8 of an inch. their minuteness is evident. Their flat, blackish bodies are covered by finely netted, gauze-like membranous wings.
At the widest point across, they measure only 2 to 2.4 mm. from the edge of one wing to the other. The head is covered by a hood resembling the wings in texture and pattern.
Rhododendron Lace Bug
The margins of the thorax are also membranous, expanded, and flaring erect. The rhododendron lace bug is a uniform, dingy straw color, whereas the azalea lace bug has some smoky brown markings, and the andromeda lace bug has a similar pattern of blackish hue on the hood and front wings. The three kinds are readily distinguishable.
Shortest but broadest is the species that feeds by preference on rhododendrons and mountain laurel. It is a native American form and looks very unlike the other two, both of which are of Oriental origin. This native insect has a very small hood and the front wings arc more broadly rounded at their distal ends. The surface of the wings has numerous, fine, silky hairs.
Of medium length is the azalea lace bug with a much larger and more rounded hood than the rhododendron lace bug. The surface of the wings is smooth and, except for scattered markings, the membranous areas are transparent.
This insect selects different types of azaleas, including certain evergreen varieties as well as deciduous types, for food plants. It bears a marked resemblance to the third species.
Andromeda Lace Bug
The body length of the andromeda lace bug averages a bit longer than the other two. It has by far the largest, most globose hood, and the dark markings are in sharp contrast. on the otherwise cellophane-like body surface. This insect feeds almost exclusively on the foliage of the Japanese andromeda.
The life cycles of both the rhododendron and azalea lace bugs are reasonably well known, and the evidence at hand suggests that the life history of the andromeda lace bug is essentially the same.
The three insects discussed here are members of the same genus. Unlike other temperate zone lace bugs, these species live over Winter in the egg stage.
They lay their eggs in the leaves of their host plants. They insert the basal end of an egg into the leaf tissue on the tower leaf surface, commonly close to a vein. On the evergreen plants, the younger leaves are selected and these remain on the plant all Winter.
Eggs laid in late Summer will hatch when the weather becomes favorable, late the following May or in June. The young nymphs feed after hatching and molt five times, at three to six-day intervals, to pass through five nymphal stages before transforming, at the time of the fifth and final molt, to adults.
Depending on temperature, availability of food and other environmental factors, development from hatching to maturity requires a month or more. The adults feed and mate to produce eggs for the next generation. In New Jersey and Southward, two or three broods may occur in one season. In central New England, probably only one cycle is completed annually however, since the climate is more severe.
How To Control The Azalea Lace Bug
Since lace bugs feed by piercing the epidermis of the leaf and extracting the fluid substances from the tissues within, they are controlled by contact poisons. To effect good control, careful spraying or dusting of the under sides of the leaves is essential.
The aim is to cover the insects themselves with suitable contact insecticides – like the all-natural pesticide neem oil or insecticidal soap. The major problem comes with spraying the under leaf surfaces thoroughly, since lace bugs seldom gather elsewhere. This can be done by using powerful sprayers equipped with the proper nozzles.
The best control is obtained by spraying early in the season when the eggs begin to hatch. Spray about five days after hatching starts and a second time five days later, or as weather conditions and the lace bug population dictate.
Since the azalea lace bug may infest deciduous plants, practice garden sanitation procedures in Fall and Spring, such as the raking and burning of fallen leaves that possibly bear eggs. This should greatly reduce and limit the possibilities of a heavy infestation developing.
Regular examination of the plants during the growing season and prompt spraying when indicated will prevent the growth of a large population with injury to the shrubs.
The Flame Azalea: Full Flower Breath-Taking Colorful Beauty
Everyone who has ever traveled through the southern Appalachian Mountains in late spring is familiar with the breath-taking colorful beauty of the flame azalea (Azalea calendulaceum) when it is in full flower.
Although plant hunters have searched the far corners of the earth for rare and beautiful shrubs for our gardens, this native azalea can still be placed at the top of any list of shrubs with brilliant spring blooms.
Like other azaleas and rhododendrons, it requires an acidic soil where hemlocks, pines and oaks abound, as well as a normal amount of soil moisture.
Given these two requirements, there is little else this ornamental azalea demands. Normally it grows no higher than 9 feet.
Fortunately for gardeners, the color of the flowers varies from a light yellow to a rich orange red. Most plants will have orange flowers, but where hundreds of seedlings are grown, the other colors will crop up.
Commercial propagators long ago realized the value of the yellow and reddish-flowered clones and began to propagate them asexually.
Propagating the flame azalea is best done by seed, which ripens in the dry capsules in the fall.
It is cleaned and kept dry until early spring, when it is sown on a very fine layer of moist sphagnum moss.
Propagation by cuttings is extremely difficult and is best left to the experienced commercial propagator.
The flame azalea blooms with some of the mock-oranges, beauty-bush and arrow-wood (in early June in New England).
Its most important feature is its ability to retain its flowers in good condition in full sunshine for almost two weeks.
Since few azaleas bloom this late in the spring, the flame azalea is valued in extending the flowering sequence of this colorful group.
Occasionally, though not always, the flame azalea foliage may have a rich reddish tinge in the fall. lt is easy to prune and care for if given a good start in the right kind of soil.
image: wikimedia commons