Growers are often quick to notice random changes in their cannabis plant. They are acutely aware of problems and even a minor difference can set them off. So when your cannabis leaf stems start to turn red or purple, you might be scratching your head as to why.

It’s quite common to see cannabis stems change color and they are an indicator of a few potential issues or just a genetic trait.

If your cannabis stems turn red it could be because that particular strain has that characteristic. Otherwise, it could be an issue with temperature fluctuations, light stress, PH lockout, or a nutrient deficiency. Keep an eye out for other symptoms to verify the cause.

Keep in mind that red or purple leaf stems are more common than you’d think so it more than likely isn’t a cause for alarm. But when growing cannabis, it’s better to be safe than sorry. Here are some of the causes for red leaf stems in cannabis.

What Causes Cannabis Leaf Stems To Change Color?

The list of possibilities is pretty small when it comes to stems changing colors and if your grow settings are dialed in then it’s probably just a natural coloration.

Plant Genetics

There are so many strains of cannabis out there that you’re bound to come across a plant that will have some odd coloration to it.

Not only can it impact the color of your leaf stems but it’ll change the color of the fan leaves, flowers, and even pistils. Common colors that you’ll see are purple, orange, and red. If nothing else is wrong with the plant then this is the culprit.

Nutrient Issues

Whether it be a PH lockout or you are deficient in cal-mag, a common cause of stem color is due to nutrient issues. The easiest way to spot this would be to look at your fan leaves to see if there is any discoloration or yellowing.

Usually, the plant stalk will also change color, more like purple than red. This is an indication of a cal-mag deficiency. If your nutrients are in check then ensure that the PH of your water is in the correct range to rule out lockout.

Light Stress

Cannabis loves strong light, but sometimes it needs a little help to stop it from getting damaged. Instead of adding sunscreen to the sensitive green stalks, it will change the color to red or purple.

This is to protect itself from any UV damage and doesn’t necessarily mean that anything is wrong. If you notice your fan leaves starting to suffer from light burn then you know your light is too strong.

Final Thoughts

As you can see, red fan leaf stems aren’t as urgent as something like a pest infestation. Just be sure to eliminate all of the common culprits and it won’t affect your growth.

If your plant is one that produces exotic colors then it’ll be interesting to see how it finishes off the flower cycle. Usually, buds will start to change colors with the sweetleaf around them and it can be quite the color show.

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