Rhododendron Leaves Turning Yellow – Complete Analysis

When planted correctly, the rhododendron shrub is a beautiful flowering specimen in many environments and requires relatively little maintenance. The ideal planting location for the rhododendron shrub is necessary for healthy rhododendron growth. For the survival of this acid-loving plant, proper soil treatment is also essential.

Before growing the Rhododendron in spring, soil preparation is best done in October. The USDA zone that Rhododendron grows in will determine when to plant it. Rhododendron cultivation is demanding, but with the correct soil and setting, the rhododendron shrub will function at its best.

Maintaining Rhododendrons

After carefully placing the plant in the planting bed, water it well, and then cover it with an organic mulch that will eventually degrade and provide nutrients. It is believed that a pine bark coating placed at a depth of 2 inches (5 cm) can prevent root rot-causing fungus. It is improper to use peat moss as mulch since it is difficult to rewet once it has dried up.

Rhododendron maintenance will be less necessary in the future with proper mulching. The ideal times to fertilize rhododendrons are in the fall, just after a severe winter, or in the early spring. Use organic cottonseed meal or another type of fertilizer for plants that like acid.

Rhododendron maintenance will be less necessary in the future with proper mulching. The ideal times to fertilize rhododendrons are in the fall, just after a severe winter, or in the early spring. Use organic cottonseed meal or another type of fertilizer for plants that like acid.

Suppose you could avoid allowing the rhododendron bush to go through the stress of withering. Rhododendrons can be planted with shade-loving annuals like impatiens to serve as a water indicator. Rhododendron cultivation begins with adequately adjusted soil and replanting in the appropriate area.

Rhododendron maintenance is made easy with the help of these procedures. Once correctly positioned, the Rhododendron merely requires appropriate watering, trimming, and flower deadheading to promote its robust regrowth.

Rhododendron Planting Season

Plant the rhododendron shrub when the risk of frost has gone in the spring. Because wet and waterlogged roots are the primary cause of crop failure in the landscape, plant the shrub high in well-prepared soil. The rhododendron shrub will probably be bought as a balled and burlapped specimen or as a containerized plant. Before planting, the root ball must be moistened. Rhododendrons require moisture to thrive. Put the plant in a tub or bucket and give it a quick bath until the air bubbles disappear. Rhododendron shrub should be planted with its crown at the same height as it was in the pot.

Rhododendron Planting Soil Preparation

For a rhododendron shrub to develop, the pH of the soil must be just proper. On the pH scale, the ideal range is 4.5 to 5.5. The most accurate approach to measure the pH of the ground and add nutrients is through a soil test. Rhododendron beds should not be amended with aluminum sulfate; instead, use agricultural sulfur since the aluminum may damage the developing Rhododendron.

Putting the rhododendron shrub in prepared beds in clusters rather than individual planting holes is preferable. Rhododendrons will require less maintenance if grown in loamy, rich soil with the correct pH that retains moisture yet drains quickly. A 50/50 ratio of organic matter is recommended as a soil supplement since it improves drainage and aeration while also allowing the rhododendron shrub to grow taller.

Reasons for the Yellowing of Rhododendron Leaves

The solution to the question “Why do my rhododendron’s leaves have yellow hues?” might range from insufficient watering to wrong planting to inadequate soil. You must assess your cultural practices to identify the issue and implement the necessary measures for curing yellowing rhododendrons.

Organic Yellowing

If your rhododendrons are 2 – 3 years old and the leaves will turn yellow and die off shortly before winter, this is a normal stage of the life cycle and is nothing to be concerned about.

Moist Soil

You should first and foremost check for good drainage if the leaves on your rhododendrons are becoming yellow, particularly around the veins. Rhododendrons can not thrive in moist soil, which can cause yellow discoloration. Water your plant to determine how quickly the water absorbs into the ground.

If your property has poor drainage, you might need to move your shrub (between October and March) to a more advantageous location. Dig a small hole, fill it with water, and leave it for 24 hours. Then, check whether there is still water in the small opening to determine whether you have poor drainage.

The Ph of Soil: Acidic Rhododendrons Must Have Soil To Grow

A household pH test kit should determine the soil’s acidity. Your Rhododendron may need to be moved if your soil tests alkaline since it will lack the necessary minerals. Since the ground is acceptable, whether it is neutral or highly acidic, the cause may be hard water, specifically if your rhododendrons are in pots.

Deepening the Planting

The root ball of your rhododendrons should be near the soil’s surface when you plant them. You may have buried it too deeply if you can’t feel the root ball when you feel about it. In that case, you’ll need to transplant it at the proper depth, which is best done from October onwards when the plant is dormant. The planting depth might affect how your leaves turn out, and most plants suffer from being planted too deeply.

Deficiency in Iron

Acidic soil is required for rhododendrons. They won’t be able to obtain some nutrients, like iron, if the soil properties in which they are cultivated are alkaline. Rhododendrons need iron to thrive, and a lack of it causes their leaves to develop a bright yellow color, mainly along the veins, which is quite apparent. For these kinds of plants, applying a high iron fertilizer is inadequate since the iron has to be absorbed rapidly and efficiently.

Iron deficiency may be treated most easily by applying a seaweed and iron mixture to assist the foliage in return to its former state. Seaweed promotes plant development, and the iron added to these items aids in providing the nutrients that Rhododendrons require in the proper form.

Insufficient Lighting

Like the majority of plants, rhododendrons appreciate direct, dappled sunshine. Therefore, the plant may react by coloring its leaves yellow when put in a dimly light location with limited aeration and a crowded area. Similar to this, the leaves of the rhododendron plant may become yellow when exposed to the hot, direct sun.

A thriving Rhododendron plant requires a continuous equilibrium between the extreme values of excess and partial sunshine.

Agricultural Needs

Improper fertilization is another important factor in the yellowing of Rhododendron plant leaves. The yellow leaves can indicate that the plant needs more nutrients than usual. Any plant needs high-quality fertilizer to thrive. Therefore, I advise using a slow-release kind explicitly designed for rhododendron plants.

Accumulation of Salt

Even if you love your rhododendron plant, feeding it too frequently might cause various issues, including yellow leaves. Although the rhododendron plant is relatively large, it is not a good idea to keep providing it.

Pests and Diseases

Either fungus diseases or insect infestations frequently bring on rhododendron leaf yellowing. Your plant may be sick or spider mite-infested if you see yellow spots or areas on it.

Remedies for Yellowing Rhododendron Leaves

The likelihood of your soil becoming poorly drained increases the possibility that your plant’s leaves may turn yellow. Transplant your Rhododendron where there is more drainage and ventilation. If you are an indoor grower, ensure the pot has excellent drainage holes. You can grasp some of the soil in your palm and squeeze it to verify whether the issue with the damp dirt exists. The earth is moist if it remains cohesive and does not separate.

After testing the soil, you must take the appropriate actions to restore the proper pH level. You can make use of two particular things to correct the acidity. These two are also

  1. Acidifier for the soil
  2. chelated iron

Just a little bit of each ingredient should be mixed into the soil at first. After that, recheck the pH level. If the soil is still alkaline, add extra. However, don’t apply too much at first because a low pH might also result in yellowing.

Removal should be your primary priority to any sick or dead leaves by cutting them off and burning them. There will be less chance of the infection outbreak as a consequence. The fungus can then be killed using a fungicide.

If the water is chalky, avoid using it for irrigation. Instead, use roof-collected rainwater. Testing your soil is one option, but it is preferable to inquire about it as gardeners are often aware of the local ground’s alkaline or acidic nature. Nearly the majority of the soil in Scotland is naturally acidic. Farmers are liming soil for crops, but this wears off after about three years. Before planting, you can lower/acidify the soil pH by adding aluminum or iron sulfate sulfur.

It’s probably too deep if you can’t feel the rootball. The plant up. You could notice new roots sprouting close to the soil surface if it has been there for a while. Replant when necessary. Don’t bury the plant in mulch heaps. It takes more than 10 cm of mulch. Rhododendrons dislike membrane and bark, so avoid using them.

Rhododendrons require certain minerals. The majority of these are naturally present in soils. Rhododendrons, however, absorb too much calcium and not enough iron in alkaline soil. Iron chelates or sequestrate can be added to the diet to aid, but this is typically a waste of money and effort.

Remember that drafts are not just possible during the winter and that a too active air conditioner may also be the culprit when considering whether your plant could be developing a cold. Also, remember that your plant could require less watering because the soil won’t evaporate as rapidly in a more relaxed setting. Your plant can be becoming water-logged in addition to being chilly due to a cold draft.

It may indicate a nitrogen deficit if your plant’s new leaves are a very light shade of green while the older leaves are becoming yellow. To prevent fertilizer burn, look for plant foods containing this nutrient and feed at the appropriate rate. Your plant will quickly regain its lush appearance with the correct quantity of fuel.


Yellowing leaves are among the first indicators that your plant is in crisis, as anybody who has ever had a plant and been worried about it will attest. Finding the exact source of your plant’s disease can be challenging, though, since several potential root causes might include insect issues, overwatering, and underwatering.

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