Azalea Hill Nursery, Inc.
Azaleas are some of the most commonly used woody ornamental plants in the landscape from the Central Gulf coast to the Mid-Atlantic States for good reasons. They provide excellent evergreen foliage throughout the year and a magical array of colorful flowers during the spring. Azaleas come in many colors and varieties that can acclimate to the many different hardiness zones of the southeast.
It is a common misconception that azaleas are very high in maintenance and difficult to keep healthy and beautiful. Azaleas do not require significantly more maintenance than other woody ornamental plants just the right maintenance at the right time. On this page you will find the detailed information needed to obtaining the proper understanding of azaleas and their required maintenance. Utilizing this information will greatly assist you in having quality azaleas in your landscape.
- Azaleas prefer partial shade. Growing azaleas in the full sun is possible, but the plants will require extra attention. When you are out in the full summer sun, you require more water and food, so do the azaleas. This needs to be taken into consideration.
- Select the right variety for the location desired. Make sure you understand what is the mature height of the variety selected. There is nothing wrong with planting a larger growing azalea in an area where the desired height is 4 feet but understand that it will require more radical pruning. (Note: Azaleas do like to be radically pruned, see section on pruning.)
- Make sure of your agricultural hardiness zone. This information can be obtained from garden centers or your agriculture extension office. Do not expect a plant zoned for 9b to survive the winter of zone 8a unless you are willing to protect it.
- Most importantly, an adequate water source is a must. Remember, azaleas have a shallow root system and they require more water than other woody ornamentals, especially during establishment. (See section on water.)
- Azaleas prefer a soil ph of 4.8 - 6.2, with 5.5 being ideal. In most cases ph is rarely a problem, if the soil ph is outside these guidelines, the soil will need to be amended. (See section discussing stress.)
- Every soil situation is different. If water drains to quickly or to slowly you might want to consider digging the hole twice the size of the root ball and adding peat moss or some kind of potting soil. This will help the plant to establish more efficiently. Milorganite in the hole or around the base of the plant after it is planted will also aid the plant in establishing.
- Mulching is recommended to help retain moisture, reduce weeds, cool the soil, and protects the shallow roots in the summer.
- Spacing. The general guidelines for spacing are as follows: 18-24" apart for one-gallon size plants. 36-48" apart for 3 gallon plants.
- Don't forget the water.
- With so many different kinds of fertilizer on the market it is hard to make a recommendation. Here are some guidelines that are usually effective: Select a fertilizer with a nitrogen (N) level no higher than 12, unless the fertilizer is time-release, then you can use a fertilizer with a nitrogen level up to 18. (In time-release fertilizers the nitrogen is released slowly over time, this greatly reduces the risk of burning.) The phosphorous level (P) should be between 4-10, and a potassium (K) level between 8-14. For the professional, commercial time-release fertilizers, such as Osmocote or Harrell's Polyon, work very well. The homeowner should consult with your local garden centers about other time-release fertilizers that may be available. Obviously, quality fertilizers cost more initially, but are safer, last longer, go further, and provide the plant with elements not generally available in inexpensive brands. Cheap fertilizer is usually just that, "cheap" fertilizer.
- Fertilize azaleas after the threat of the last freeze and after the spring flowering period has ended. Frequency depends entirely upon the type of fertilizer used and weather conditions.
- Experiment with the fertilizer by using the lowest recommended rate, find out what the plant likes. You can always add more but you can't take it away.
- Proper pruning is important to maintaining a full, vigorous azalea, which will bloom heavy in the spring. Improper or no pruning is usually the culprit for ugly azaleas. Azaleas should be, and like to be, "hard" pruned sometime after they bloom until around the first of July. "Hard" pruning after this time could reduce the number of blooms the following spring. Hard pruning is defined as, trimming as many of the branches as possible, even cutting into hard wood if necessary to establish a base. Remember, the plant has all year to grow, so cut it back far enough to avoid hard pruning after the desired time.
- Long shoots of growth that stretch above the base later in the year are called "terminal" shoots. Spot cutting "terminal" shoots can be done at anytime of the year except winter. Spot cutting terminal growth is also important to maintaining a full plant and should be done as needed through the fall.
- The three most important steps to having healthy azaleas is water, water, and water! It is impossible to have beautiful azaleas without the proper amount of water. Lack of water is the number one reason why azaleas struggle.
- There are ways today to properly irrigate azaleas with little effort and without violating local water restrictions. There are many types of low volume emitters, spray heads, and soaker hoses that work particularly well. These methods can be used with or without an irrigation system and in many cases are not subject to local water restrictions. With these methods there is little or no waste because they emit low volumes of water directly at the base of the plant that goes in the ground to be absorbed by the roots. The excess goes back to where it came from with no runoff.
- It is recommended that plant areas be on separate irrigation timer zones because what is enough for the grass may not be enough for the plants and vice versa.
- As with all new landscape, newly planted azaleas will require more water than established ones. Experience suggest that it takes about two years for an azalea to fully establish. During this time, monitor your irrigation and adjust accordingly, especially during dry, hot conditions.
- When it is raining turn your sprinklers off! What a waste, and it leads to a prime environment for fungus. Wet soil does not need to be watered! Come on man! With all turf and landscape you need to monitor the water and adjust as conditions dictate. Some might say, "Oh, that's too much work." Then, may I suggest concrete?
- The most common problem that azaleas face is problems related to stress. Stress is usually attributed to lack of proper maintenance. Lack of proper water is the most common causes of stress. Improper fertilization, insects, diseases and extreme weather conditions also play a factor. When an azalea is stressed the leaves usually turn yellow with the veins in the leaves staying green, this condition is called "chlorosis". Chlorosis is sometimes miss-diagnosed as a ph problem. While too high or too low of a ph will cause chlorosis, this problem is mostly stress related. The solution is to identify the cause of the stress and to change management practices. Repeated applications of a nutritional spray may help restore the plant. Nutritional sprays contain important minor elements, with iron being the primary element. Also, an application of Milorganite has been proven effective in helping the plant cope with problems related to stress. Ph is rarely a problem, but if a soil analysis detects a ph problem, then and effort must be made to adjust the ph. A low ph can be raised with a prescribed application of dolomite. It is a lot easier to raise ph than to lower ph. If the ph of the soil were over 6.2, azaleas would not be recommended. If you choose to try an attempt to lower the ph, you would use a prescribed application of granulated sulfur or iron sulfate.
- Fungus is a disease related to excessive moisture. Leaf fungus can be identified by brown spots on the leaves or with the leaf turning brown then black and eventually falling off. Fungus is not usually a problem in the landscape if one follows good management practices, such as properly monitoring the water. If fungus does become a problem, fungicides containing thio-phanate methyl or propiconazole work well. These ingredients are found in many types of fungicides available in garden centers. They should be listed on the label as active ingredients. Copper is also effective.
- Root fungus can be a little more difficult to diagnose and treat. Root fungus can cause leaves to curl, yellow, or become deformed. A plant with root fungus may even wilt even though it is wet. This is because the roots are deteriorating and cannot pick up the needed moisture in hot weather. Root fungus needs to be treated by a professional applicator using commercial products like Subdue or Aliette.
- Insects on azaleas in the landscape are relatively minor problems and are usually taken care of with the application of basic insecticides. Lace bugs are the biggest concern. Lace bugs suck the chlorophyll out of the leaves causing them to be speckled white. If this problem is not taken care of aggressively the damage can be significant. Catepillars, azalea leafminors, and spider mites can also be a problem. Insecticides containing Imidacloprid or Bifenthrin are very effective. (Check the active ingredients on the insecticides label.) Usually two applications, 10 days apart are recommended. Mites may require three applications, 7-10 days apart.
- If your insect and or fungus problem is on more than just a few plants, consulting professional applicators is recommended. Commercial applicators have access to a wide range of insecticides and fungicides to better combat the tough jobs.