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Pepper Stem Turning Purple – Here’s What Causes It!

Growing peppers is a great way to get into gardening. They are relatively hardy, great to grow in summer, and are a delicious addition to many meals. Different varieties of peppers grow in different ways. Sometimes, certain pepper plant stems will turn purple as they grow, a regular part of their life cycle. Other times, a purple stem means something much different is going on with your plants.

Purple pepper stems are typically caused by nutrient issues. Lack of water, cold weather, and even fungal diseases like blight can cause this change in pigmentation.

In the article below, we will discuss why some pepper plant stems naturally turn purple and what else purple stems could mean. Keep on reading!

Why Do Some Pepper Plant Stems Naturally Turn Purple?

As I have mentioned, there are some types of pepper plants whose stems naturally turn purple as part of their growing process. The pigmentation affecting these pepper plants and other fruits and vegetables is called anthocyanins.

They are simply the pigmentations of deep red, purple, and blue that color plants. This pigmentation in pepper plants is found in their stems, branches, leaves, and fruit, but most of all, in their seeds.

There is no reason to worry if you see this pigmentation without any other symptoms of something going on with your plant. It is exactly what is supposed to be happening.

Why Else Do Pepper Plant Stems Turn Purple When It is Not Natural?

If you notice your pepper plant stem turning purple, and there are other symptoms, such as discolored leaves, wilting, decay, etc., this is not normal, and something greater is happening to your plants. Here are some things to consider.

Nutrient Issues

Like all living things, pepper plants need nutrients to grow and thrive. However, if there is an imbalance of nutrients, either too much or too little of something, it can cause issues in plants. Deficiencies in phosphorus or magnesium will cause the plant to turn purple.

Nutrients like phosphorus and magnesium help balance the sugars in all plants, including pepper plants. They also help the photosynthesis process, keeping the plant healthy, happy, and green.

Too Much Water

Pepper plants, in general, need around 1 inch of water per week. They aren’t the heaviest of water feeders; for instance, tomatoes and cucumbers need around 2 inches of water. However, it is still vital to ensure you properly water your pepper plants.

Too much water in pepper plants can cause their stems to turn slightly purple, and the rest of the plants may start discoloring. When a pepper plant has too much water, oxygen and nutrients cannot flow freely through the plant’s roots and stems.

The plant is essentially flooded. Blockages and build-ups can happen within the plant’s stem systems, which would cause the plant stems from looking purple.

Cold Weather

Cold weather is one of the leading causes of purple stems. Since pepper plants are warm weather plants, summertime plants do not do very well in cold weather. Their ideal temperatures are between 75-90. Cold weather, especially freezing weather, will cause the cells in the stems to die, thus creating a purple color.


Blight is a fungal disease that affects almost every plant in the garden. It is a fast-acting, nasty disease for which there is no cure. Blight is also a form of rot.

You will first notice brown, purple marks on the stems and leaves of the pepper plants. Later, you may see strange-looking white growth at the base of the plants. The leaves will fade, discolor, turn yellow, and eventually, the plant will start dying.

How To Fix A Pepper Plants Purple Stem

If you can catch the problem immediately, there will still be time to reverse the purple-looking stem, and your yield will not be badly affected.


If you believe your plant’s stem is purple because of a nutrient issue, as soon as you can, you must give your plants a liquid feed with phosphorus and/or magnesium. Start doing this once a week until you start seeing results.

Preparing and feeding your plants before symptoms show up is the best way to ensure this problem will never happen. Before you even plant your peppers, you can mix the soil with a healthy, well-balanced fertilizer with an NPK of 10-10-10 or something similar.

Most fertilizers already have small amounts of magnesium, so you should be fine. However, if you notice purple stems and leaves discoloration and looking spotty, you may have a magnesium deficiency. In this case, you can also give your plants a liquid feed of magnesium.

Water Schedule

Having all your plants on a proper water schedule is essential, so you do not have to worry about over or under-watering. However, sometimes it happens anyway, and even the most seasoned gardeners may end up improperly watering at some point during the season.

As mentioned, pepper plants need around 1 inch of water a week. It is a good idea to water your pepper plants every 2-3 days, or every day if it is very hot out.

If you think you have overwatered your pepper plants, causing the purple stems, then you should let your plants dry out for a few days. Do not water them, do not feed them anything. Just let the soil air out. Once the soil has dried, resume watering as normal, and stick to a better schedule.


You must be careful when planting pepper plants and ensure you are planting them at the right time. Often, when pepper plants are subject to cold, it is because they are planted outside too early as seedlings, and the nights still get too chilly.

To avoid this, plant your pepper plants indoors in seed trays or in a greenhouse environment until the outside temperatures are at least 60-65 consistently, even at night.

If a cold snap comes through during the summer, you can try and protect your pepper plants—Lay mulch around the base of the plants to hold in any heat in the soil. You can also lay plastic over your plants (like a greenhouse) which traps heat. Place cardboard, leaves, shade cloth, or anything else over your plants at night to keep them warm.


Unfortunately, with this particular disease, there is no cure. It is a nasty disease that will attack your whole garden if you are not careful.

Once you notice the disease, remove the affected plants immediately. DO NOT compost plants infected with blight; this will further spread the disease. Instead, you must burn your plants or throw them in the garbage.

To prevent the disease from returning, you can sun-treat your soil. You do this by watering in hydrogen peroxide, then letting the soil soak and sunbathe for at least a season. When you are ready to plant in the soil, rotate your crops. Never plant the same thing twice.

Final Thoughts

There isn’t much to worry about if you notice your pepper plant stems turning purple. Most of the time, it is just their natural growth cycle, and the color change is supposed to happen.

You may have other issues if there are other symptoms, such as discoloration on the leaves, wilting, or leaves dying. If you catch the problem immediately and fix it, your yield will be unharmed. Happy gardening!

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