If you notice your Coleus leaves turning white it can be quite alarming, but what causes this to happen?
Coleus leaves can turn white for a few reasons ranging from excess or lack of sunlight, diseases such as downy mildews or due to an inability of the plant to produce enough chlorophyll (known as chlorosis). There are also certain varieties of Coleus that produce white on their leaves naturally.
Let’s take an in-depth look at 5 reasons why your Coleus leaves can turn white, and what you can do about it.
5 Reasons For Coleus Leaves Turning White
If you keep your Coleus in bright, direct light for extended periods of time you risk sunscalding the leaves.
This creates white patches, and once leaves have been sunscalded they have to be removed as you cannot repair the damage.
Coleus prefer a balanced sunlight schedule, with plenty of bright and indirect light and a few hours of direct sunlight per day.
2. Downy Mildews
Downy mildews are caused by fungus-like organisms and can result in the growth of white mold on Coleus leaves.
As the mold develops it can seem like the entire leaf is turning white.
Downy mildews thrives in damp conditions, so make sure you give your Coleus plenty of time to dry out after watering and avoid soaking the leaves in water. Down mildews can be treated by removing affected leaves and avoiding conditions that promote growth (excess moisture).
3. Low Light Conditions
Lack of sunlight is one of the most common reasons why a Coleus can start to turn white.
This is because Coleus plants (like others) use sunlight to produce energy via photosynthesis. Without enough sunlight, photosynthesis cannot take place properly which deteriorates the pigment on the leaves.
Chlorosis is a term used to describe when a plant is unable to produce enough chlorophyll.
Chlorophyll is responsible for turning sunlight into energy, so if a Coleus is suffering from chlorosis it can start to turn white as it loses its ability to photosynthesis. The first stage of this is usually yellowing of the leaves.
Chlorosis is commonly caused by a lack of nutrients, poor drainage and compaction of soil or from drought conditions. Avoid overwatering your Coleus, and make sure that the soil is nutrient-dense but also well-draining.
5. Natural Pattern
At the time of writing this article, there are 294 known species of Coleus, and a lot of these have very different and vibrant colors and leaf patterns. White is just one of many colors that can appear on a Coleus depending on what type it is – for example, the Wizard Rose variety naturally has a creamy white coloring on its leaves.
These patterns and colors can become more intense when a Coleus is subject to more sunlight. So, your Coleus may be starting to turn white due to its pattern emerging in the presence of sunlight.
This is more common than you would think, as a lot of garden centres don’t identity specific varieties of Coleus that they are selling. Looking through popular Coleus varieties is an easy way to figure out if the white coloring developing on your Coleus is normal or not.
Can White Coleus Leaves Gain Color Again?
If your Coleus leaves have started to turn white they won’t recover.
The best thing to do in this case is to prune any leaves that have been affected and address the underlying issue. Make sure your Coleus is receiving the correct amount of sunlight, safeguard against diseases like downy mildew and make sure that the soil is nutrient-dense and well-draining.
Don’t forget that some varieties of Coleus have white pigment on their leaves naturally, so it may not be something to worry about.
Coleus leaves turning white is almost always a sign that something is wrong unless your particular variety has white pigment naturally.
Focus on getting the basic care requirements right and you shouldn’t have anything to worry about.