Your Pilea is turning red on either the stem or the leaves, and you’re wondering what you’ve done wrong. Correct? In this post, I’ll take you through the all facts you need to know and tell you exactly what you can do. Keep reading!
What happens when Pilea stems turn red?
As a plant owner, it can be grueling when your precious plant changes its appearance. Plant biology is a complex world, but you can come a long way with a bit of research. Let me take you through it here;
As your Pilea ages you will notice that the stem will take on two different looks:
- A tree-trunk like texture and color from the ground and up
- A bright green or red color on a section of the plant with new growth (the top)
The red color is caused by the pigment Anthocyanin
The cause for the red color developing in your plant has to do with the red pigment found in plant cells called anthocyanin.
The color red can either occur because of an increase in anthocyanin, or a decrease in chlorophyll, which produces the color green.
Anthocyanins’ greatest purpose is to protect a plant from environmental stress. The pigment is an antioxidant that helps with repairing and protecting plant cells, especially against high levels of light and drought which causes stress to the plant.
New growth is particularly sensitive when it comes to environmental stress as it’s going through a development phase, and it’s therefore not surprising that it is exactly on new stem growth where we often see the red color occur on Pilea.
Meaning, the red color on a Pilea stem is completely normal and nothing to worry about.
Why are some stems red but not all?
So if new growth needs extra protection given by anthocyanin, why are not all Pilea stems red?
The production of anthocyanin is typically triggered by sunlight, and if you have a plant (or have seen a plant) that does not have the red color on new growth, it’s most likely because it hasn’t accumulated enough of the pigment due to a more shaded position.
With exposure to bright light, your plant is faced with high levels of radiation and heat, and anthocyanin actually protects the plant against damage from the sun and helps with reducing evaporation. Pretty smart, huh?
Solution to a Pilea with red stem
Typically, the red color will remain until this particular section of the plant is done growing. The color will then turn back into a shade of green, and eventually take on the tree trunk-like appearance.
As mentioned above, the red color is not a warning sign of anything being wrong with the plant, as people are otherwise quick to point out on various forums. However, if you do not like it, you have the option of moving the plant to a spot with less light.
Red leaves can be caused by poor drainage
In the early days of experimenting with Pilea Peperomioides, I had a high mortality rate. After a while (and the purchase of a moisture meter), I came to suspect claggy soil killing the plant inside out.
If the leaves on your Pilea are turning red, another problem could actually very well be the soil itself.
In cases of soil with poor drainage, the soil will have a low level of oxygen which slowly kills the roots.
As the roots rot away, the leaves will struggle to soak water, and thereby cause stress to the plant. This state is called hypoxia, and what you will often find along with red leaves, are leaves that are smaller than usual.
Solution to red leaves on Pilea
If you suspect claggy soil, a good solution is to repot your Pilea into fresh soil and do a better effort of providing drainage. For example by adding leca, rocks, or mixing it with a lighter material such as gravel or sand.
Keep in mind, that mixing soil with gravel/sand will increase the need for watering as these materials do not contain water well.
The process of leaves turning red due to Hypoxia typically starts along the edges of the leaves as seen in the photo below.
Lack of the nutrient Phosphorus
According to Dr. Linda Chalker-Scott, Ph.D. in Horticulture and associate Professor at Washington State University, red leaves caused by a lack of Phosphorus are most often seen with intensively grown crops, and rarely at home.
People and various media are quick to suggest adding fertilizer rich in Phosphorus when seeing red leaves, but this is likely to not be the actual problem, and adding fertilizer could do more harm than good.
Solution to lack of nutrients causing red leaves on Pilea
If you suspect a lack of nutrients, you have the option of doing a soil test that will provide data on nutrients, contamination and pH. If a soil test does come back showing a lack of nutrients, then you need to find fertilizer with the correct mix of nutrients for your plants deffiency.