We all want the best for our plants and hope to do whatever it takes to grow and care for them.
Sometimes, no matter how hard we try to do things right, things can happen by accident or we can’t control them.
Fortunately, the causes of rhododendron leaf reddening can be identified and corrected once you know which cause is to blame.
So if your rhododendron plant doesn’t look normal, it’s time to take a closer look at what could be causing the red leaves.
too much light
While rhododendrons can get full sun for a few hours a day, you really don’t want to go over that, as it can be a pretty big cause of red leaves from sunburn.
Rhododendrons are naturally grown in shade for most of the day, so exposing them to too much light, especially bright light, can cause problems for the plant.
This also applies to heat in general, as hot summer days can destroy many types of plants.
Sunburn is also a major cause of black leaves on a rhododendron.
Rhododendrons grow and look best when grown in cool temperature climates, so you’ll want to avoid growing them outside when the temperatures start to get very hot.
Too much light or hot temperatures can also affect or prevent the plant’s flowers from blooming.
In fact, rhododendron plants are best grown in a temperature range between 50 and 75 degrees Fahrenheit.
Solution
If you are growing outdoors and the temperature is above the ideal range, it may be time to start growing indoors.
If you grew indoors and too much light is causing red leaves, your rhododendron may be too close to a window.
Most plants should be at least 30 cm from windows to prevent the sun’s rays from hitting the foliage.
If the leaves have sunburned, turned dark red or brown, you will unfortunately have to prune those irreparable leaves.
A nutrient deficiency
Lack of nutrients is also a cause of red leaves on a rhododendron.
If you have noticed the leaves turning red or yellowing, you may be lacking nutrients or the soil pH is not correct.
When it comes to nutrients, rhododendrons need adequate amounts of nitrogen, potassium, magnesium, iron, and phosphorus to grow healthily and thrive.
When it comes to soil pH, rhododendron plants are acidic soil loving plants and should be kept in a soil range between 4.5 ph to 6.0 ph.
If the pH rises above 6.0, the soil pH will shift further into the alkaline range and excessive alkalinity is one of the major causes of nutrient loss in these plants.
Solution
If you think your rhododendron is suffering from nutrient loss, there are things you can do to correct this problem.
First you need to check the pH level of your soil.
You can do this with an affordable home tester.
If you find that the soil pH has become too alkaline, you can add well-rotted compost rich in organic matter to lower the soil pH to a more acidic level.
You can also use products like aluminum sulfate to lower the pH.
Now that your soil is in the right range, you can still use a well-balanced fertilizer to give your Rhododendron the nutrients it deserves.
Just follow the manufacturer’s instructions and you’re good to go.
Keep in mind that fertilizers can be quite harsh on plants, so you will usually need to dilute the fertilizer to about half to be safe.
Below are some questions and answers related to this topic which I hope will be helpful and clear to you.
Do rhododendron leaves turn red in summer?
If you notice your rhododendron leaves turning red in the summer, this may be attributed to the plant getting too much light or the heat being too much for the plant.
Rhododendrons should be grown between 50 and 75 degrees Fahrenheit in partial shade to prevent this from happening in the summer.
Do rhododendron leaves turn red in the fall?
This is where things can get a little tricky, as some rhododendron varieties turn red in the fall and others don’t turn red in the fall.
There are so many that can and so many that don’t, so you’ll need to research your specific variety to get a clear answer as to whether yours should change color in the fall.
Do rhododendron leaves turn yellow and red?
If you notice your rhododendron turning yellow and red, it’s probably nutrient deficient.
Remember to keep your soil pH between 4.5 and 6.0 so your rhododendron can get plenty of nutrients like nitrogen, potassium, phosphorus, and magnesium.