To keep azaleas looking healthy, it’s essential that you practice proper care but even then things can still go wrong. That’s why Gardening Know How is here to help by providing the best information possible – including answers to all those nagging garden questions that plaque us all. Below are our top 10 questions about azaleas.
This may actually come as a surprise, but normally fertilizing azaleas is unnecessary unless the plants show signs of nutritional deficiency, such as smaller yellowing leaves or stunted growth. Non-flowering could be a lack of phosphorus, especially if you’ve fed the plant a fertilizer high in nitrogen or if it’s in an area where runoff from a recently fertilized lawn tends to go. That said, it is always a good idea to have your soil tested prior to fertilizing just to be sure what, if any, nutrients are needed. If you do fertilize, opt for a balanced type and preferably one aimed at acid-loving plants. Spring is a good time for feeding azalea shrubs.
If you have a healthy looking azalea bush but it fails to bloom, the soil may either have too much nitrogen or too little phosphorous. Both of these issues can cause plants not to bloom. Have the soil tested where the azaleas are located to see which it is, and then amend the soil accordingly – usually adding bone meal to the area helps. Non-blooming in azaleas can also be due to improper pruning. Azaleas are early spring bloomers, generally, and should not be pruned later than early summer or you run the risk of cutting off next season’s buds. Frost, inadequate water or drought during bud set can be factors that affect flowering as well.
Wait after blooming has stopped before pruning your azaleas. The next year’s blossoms typically start forming at the beginning of July, so you should prune an azalea bush prior to this; otherwise, you may not get flowers the following season. Try to keep any pruning as natural looking as possible. Pick out branches outside the shape you want to achieve and cut them back. There’s no need to worry about cutting back to a connecting branch. Azaleas will typically regrow branches from right below wherever you cut. Do not cut any one branch back by more than a third.
Winter care for azaleas really depends on your region and timing of planting. If it’s their first winter, it does not hurt to cover the plants or mulch adequately for added protection. The first winter a plant goes through after being planted is always the most dangerous because it’s only marginally established and, sometimes, this can make it hard for them to survive the stress of winter, especially in cooler climates. Covering them with burlap and/or mulching the base heavily will help to protect your investment. After the first winter though, most azaleas do not need to be protected.
This lichen and will not harm the plant. Lichen is especially attracted to plants that are unhealthy, so it is a symptom rather than a cause of a plant’s decline. While lichen on tree bark is harmless, some people find them to be unsightly. If this is the case, you have a few options in ridding the plant of lichen. You can gently scrub the bark with a soapy solution or spray the plant with copper-sulfate (in spring or fall). Lime sulfur is also effective but should only be applies to the bark, as this can be damaging to the leaves and roots. Finally, thinning of the inner branches may help, as lichen typically prefers somewhat shadier locations and this will allow more sunlight to filter in.
Lace bugs on azalea are a common problem when growing these shrubs. Damage from these pests normally occurs on the leaves as silvery, white or yellow spots, as the insects literally suck them dry. Prevention is the best remedy. Since lace bugs generally attack shrubs that are already weakened due to poor fertilizing or watering, make sure to care for the plants properly. That said, if your azalea is already affected, insecticidal soap is usually effective in controlling lace bugs in late spring or fall. Neem oil may help too.
Unlike most plant galls, which are normally insect related, leaf galls of azaleas are caused by fungus. You can do some pruning to increase air circulation in the plant and also make sure you are watering from below rather than from above. Keeping the humidity down will help keep the disease out of the leaves. Weekly applications of neem oil can reduce the number of viable mold spores once the leaves start showing signs of attack. Also, try to keep the plant as healthy as possible, as this disease is attracted to plants that are weakened by other problems.
Yellowing leaves is normally an indication of stress. An occasional yellow leaf now and then isn’t anything to get alarmed about. However, if this is affecting more than one plant or a large amount of foliage, it could signal a problem – like a nutrient deficiency or a drainage issue. Have your soil tested, then amend it accordingly and make sure that plants are not in standing water. Also, did you fertilize it recently? Azaleas are easily burned by fertilizer and may lead to leaf yellowing with subsequent leaf drop. Finally, check around the base of your shrub for any holes. Voles and chipmunks are known to occasionally burrow down around azaleas and then make dens in their root systems. This can cause yellowing and the demise of your plants.
Azalea root systems are not too extensive and transplanting shrubs like this can be done successfully with proper care. While it is generally best to do this in fall, you can also transplant the shrubs in spring as long as the weather where you are is not too hot. Just make sure to dig up as much of the root system as possible and place it in a suitable location. Also, water the azalea well after transplanting. It may help to trim the shrub back too, though this may reduce blooming next season but will help reduce the chance of transplant shock.
Have you been fertilizing? Slow decay like this normally happens due to prolonged nutrient loss. Have the soil tested, and in the meantime, give them some higher acid fertilizer, like Holly Tone. Dieback of azalea branches can also be attributed to pests or disease, like borers and Phytophthora fungus. The best treatment is to cut back affected branches in early spring or late summer (note, this will affect flowering). If plants aren’t infested with borers, or have only a few noticeable holes, simply improving care should help. If insects are feeding on the leaves, spray the undersides with insecticidal soap or neem oil. You can help azaleas resist disease by providing them with good drainage and overall growing conditions.
We all have questions now and then, whether long-time gardeners or those just starting out. So if you have a gardening question, get a gardening answer. We’re always here to help.