Azaleas are members of the Rhododendron genus, known for its bright colors, so they are cultivated for their lovely flowers.
Azaleas are not challenging to grow. However, many individuals complain about the browning foliage. The plants can be used as ground cover, and others can be cultivated indoors.
However, it is the Azaleas turning brown that worries most. Lace bug infestations cause azalea leaves to become brown.
When an azalea plant is over-watered, the leaves become brown (root rot). In the case of fungal leaf spots, azalea leaves turn brown. In addition, cold winds cause azalea leaves to turn brown in the winter.
In our guide, you can find more about why my azalea leaves turn brown when you think you are doing things right. By the end, you’ll know more about what causes azalea leaves to turn brown. (Learn How To Save A Dying Blue Spruce)
Do Azaleas Leaves Turn Brown In Winter?
Frost or freezing damage to azalea rhododendron bud of healthy plants can cause the azalea to turn brown and die back.
Frost damage typically strikes and kills entire branches from the top-down, killing the more exposed buds of established azaleas first; thus, a frost-damaged shrub may still blossom at the bottom long after the growing season.
Planting azaleas against a south- or east-facing wall beneath an overhang and covering plants with row-cover fabric when frost threatens can help protect them from cold damage.
When the weather is cool and wet, healthy azaleas grow yet are susceptible to petal blight. Petal blight causes lesions to grow swiftly and turn brown leaves but lasts a long time on the shrub.
The flower buds can turn brown and don’t open come early spring, but later they become covered in black fruiting structures.
In diseased flowers, this twig blight pathogen overwinters as sclerotia. Mulch the bed well in the fall to keep sclerotia from germinating. Apply a fungicide one month before the plant blooms if you choose to use one.
To prevent fungus spread, remove dead branches and pick up fallen leaves from brown azaleas. Use rubbing alcohol or a bleach-water solution to clean your pruning shears between cuts to prevent fungus spread within the infected plant or between other plants. (Learn How To Get Rid Of Dandelions)
How Do I Know If My Azalea Is Dying?
If an azalea plant sits in wet soil for too long, the leaves turn reddish-brown/brown. In addition, saturated conditions suffocate azalea roots.
- Waterlogged problems around your Azaleas can be caused by either over-watering or poor drainage conditions. In addition, the roots decay in wet soil, causing browning flowers.
- Phytophthora flourishes in wet environments. The Phytophthora fungus causes crown rot and root rot in Azaleas.
- Examine the earth with your bare hands. Check the soil for wetness and dig 4-6 inches beside the roots (with a moisture meter, if you have one).
- Your Azaleas have been over-watered if the soil is excessively damp and the leaves are drooping.
- With root rot/crown rot, Azaleas’ leaf tips/leaves turn brown. Finally, the damaged azalea’s leaves wilt and become drooping.
- The roots turn brown and mushy if your azalea is infested with Phytophthora. Conversely, roots that are in good health are white.
- Crown rot causes the portion of the stem that touches the ground to turn brown.
- If Azaleas receive too much water, they will become infected with Phytophthora root rot. Later phases of crown rot are also visible.
- The most common indicator of over-watered Azaleas is leaf browning—root rot sets in if you don’t act soon.
- Azaleas can survive on just 3/4 to 1 inch of water every two weeks, even in the hotter months. So, water mindfully.
- Adding Perlite or sand to the soil will help it drain better.
- If you suspect root rot or over-watering, stop watering right away.
- Even if some roots are dark and mushy, there’s still a chance. Replant your azalea in fresh soil after washing the infected roots under running water and improve soil drainage.
- To avoid such problems, drip irrigation is a superior option.
How Do You Treat Brown Spots On Azaleas?
Browning leaves on affected azaleas can be caused by:
- Dry Soil – Overly dry soil causes soil around the roots to be dry for too long before receiving water again.
- Wet Soil – Overly wet soil from heavy rainfall or excessive irrigation causes roots to rot.
For both, test soil moisture and test soil drainage in the planting area.
Testing Soil Moisture
Dig 4 to 6 inches alongside the roots or root ball to test soil moisture.
- If the soil is wet, don’t water until the soil has dried. If the soil doesn’t dry in one or two days, it shows you could have poorly drained soil.
- If the soil is dry, add water and deep soak less often than adding a bit of water more frequently.
New azaleas check soil moisture often and adjust the watering schedule as required.
Testing Soil Drainage
After testing soil moisture and you have delayed watering, the soil hasn’t dried, showing a soil drainage problem. Now is the time to test the soil drainage. (Learn How To Get Rid Of Clover In Lawn)
Luckily, testing soil drainage is simple.
- Dig a 12″ wide by 12″ deep hole close to your planting area.
- Fill the hole with water and let it drain.
- Once it empties, fill the hole again, and how long it takes.
Well-drained soil will have water that falls about 1 inch per hour. Slower than this shows poor draining soil, which leads to constantly wet or soggy conditions. If it drains faster than this, it means you could have sandy soil and face dry soil conditions.
Improve Soil Drainage
Azaleas can tolerate brief wet or dry periods, yet they thrive the best over the long term with consistently moist but well-drained soil.
If the soil is poorly drained, you’ll need to take measures to fix the poor drainage conditions.
Improve soil drainage by lifting your plants and adding fresh, topsoil to improve drainage before replanting your azaleas. If you have established azaleas, wait until plants go dormant in winter to replant.
You can improve soil drainage by lifting and replanting each azalea plant into a raised mound. Planting in a raised mound keeps the plant’s roots higher than the water table, yet they can grow down and drink from it.
If neither works for your azalea plants, and you want your azaleas to survive, move them to an area with well-drained soil and replace them with other generally healthy plants that prefer wet soil conditions.
After adjusting the watering schedule or drainage, remove the affected leaves when any azalea leaves turn brown.
Azaleas grow best in slightly acid soil ranging from 5.0 to 6.5 on the pH scale. Most average garden soils range is 6.0 to 7.0 pH.
Testing Soil pH
Soil pH measures alkalinity and acidity on a scale of 1-14. The neutral mark is 7, below 7 shows acid soil conditions, and anything above 7 shows alkaline.
- You can test soil pH using a soil pH test kit.
- To raise the pH, add pelletized limestone to the soil, and lower pH, you can add Soil Sulfur, Aluminum Sulfate, or Chelated Iron.
- Adding organic compost or using compost as mulch helps increase acidic soil conditions for acid-loving plants.
How Do You Revive a Dying Azalea?
Fungal Leaf Spots
A fungal infection causes blotches on azalea foliage that are speckled gray or brown and look like polka dots. The patches can be reddish or practically black, with a black spot in the center.
Treating several fungal illnesses that generate brown spots on leaves is possible. Usually, this form of fungal infection does not cause any damage to the plant, though small Azaleas may lose leaves as they could with powdery mildew.
Prune afflicted parts as soon as blooming is over and rake spotted leaves that have fallen on the ground. Delete or burn these to prevent any spread.
Water promotes this sort of fungus, so water your Azaleas at the ground level rather than wetting the leaves. (Read Avocado Leaves Turn Brown Guide)
Leafminers are identified by brown patches and curled brown tips on leaves. They usually appear in the spring and spread during the summer. Some leaves turn yellow or brown and die.
The Azalea leafminer (Caloptilia azaleella) feeds on Azalea leaves. The caterpillar lives in “mines” in the leaves, brown patches, or blotches.
Leafminers usually are harmless but unattractive. Remove and destroy leafminer-infested leaves. Get rid of them away from your plants if they fall on the ground.
Because leafminers hide inside leaves, contact pesticides won’t work, but systemic insecticides will. Leafminers can be controlled with chlorantraniliprole, spinosad, abamectin, and azadirachtin.
Too much sunlight can burn Azalea leaves, and leaf scorch is common.
The leaf tissue turns yellow or brown on the leaves.
Azaleas dislike full sun but prefer dappled sun and afternoon shade.
Azalea Lace Bugs
Leaf browning in Azaleas because of severe lace insect infestation Lace bugs are dark insects that feed on the leaves.
The lace bugs’ eating habits cause the leaves’ mottling.
Leaves have white/yellow stippling. Lace bugs feed on azalea, stunting its growth.
Plant vigor is diminished, as is plant appearance. The damaged plant’s leaves will eventually turn brown.
Lace bugs do not kill Azaleas. Lace insect infestations harm Azaleas.
Use insecticides that do not kill natural predators or use pesticide alternatives including neem oil, insecticidal soap, and horticulture oil for controlling lace bugs.
Acephate can be sprayed on an affected azalea to control lace bug infestations. It’s a foliar spray that effectively controls lace bugs.
When you detect lace bugs on your azalea, use organic insecticides.
Retard the lace bug infestation in March-May to avoid future infestations
You will kill any bugs on the plant at the time of spraying. Fill a spray can with Neem oil diluted in water.