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Peppers can turn purple for any number of reasons, from natural maturation to a nutrient deficiency. Whether you’re dealing with purple bell pepper pods or purple leaves on your banana peppers, there are plenty of causes for purple peppers. I’ve seen everything from random purple stripes on seemingly healthy green bell pepper plants caused by a lack of essential nutrients that requires soil amendments, to the dark purple of the mature purple belle, which is nothing to worry about.
Peppers can be a little finnicky, so too much heat, not enough heat, too much iron, over or underwatering, and sunscald can all cause pepper plants (capsicum annuum) to show purple coloration on the leaves, stems, or fruits.
Let’s take a look at the key reasons a pepper plant turns purple and what, if anything, you can do about it.
Causes of Peppers Turning Purple
Don’t freak out if you see a purple color on your pepper leaves, stems, or fruits. It’s usually a salvageable situation, even if you see large purple streaks. And remember, you might find that you’ve got purple peppers because you chose a purple bell pepper! (The first time I grew Russian black tomatoes was purely by accident – and boy was that a surprise!)
You’ve Chosen a Purple Pepper Variety
A purple pepper plant is one that produces fruits with a deep purple or even almost black coloration. Purple peppers are among my favorite pepper varieties, as they bring more color and great flavor to dishes. Plus, remember, studies show that purple and darkly colored vegetables contain more anti-oxidants – specifically anthocyanins – and other beneficial substances than their paler relations. So naturally purple bell peppers are a great addition to your garden and your plate. But, if your peppers aren’t supposed to be purple, then keep reading to find out why and what you can do about it.
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Phosphorus Deficiency
Phosphorus is one of the most important nutrients for plants. And, if lacking, it can cause purple discoloration in both the leaves and fruits of your pepper plants. It’s most common in pepper seedlings and young pepper plants. All plants, including peppers, require adequate levels of phosphorus to form strong root systems, growing tip development, and to ensure efficient water uptake and use. It’s also vital to flowering and fruiting. A deficiency occurs when there isn’t enough phosphorus in the soil or when other nutrients like nitrogen and potassium are present in large quantities that prevent phosphorus from being absorbed properly.
Low Temperature
Peppers require warm temperatures to grow properly, which is why many gardeners choose to start their plants indoors. Then they’ll harden off their peppers to acclimate them to the before moving them outdoors once temperatures become consistently suitable for growth. Temperatures below 55°F (12°C) can cause your peppers to turn purple. The temperature tolerance of peppers is fairly narrow for solid growth and optimal yield. Cold temperatures can stress out your peppers, resulting in purple discoloration or stunted growth as well as bitter or dry fruits due to limited nutrient absorption during lower temperatures.
High Temperatures
Peppers are easy to grow, but they’re a bit fussy when it comes to temperature. Extreme temperatures can cause purple striping in peppers as the pigments, particularly in previously solid green, or unripe peppers, react to the extreme heat and express themselves as dark purple patches. Too much heat causes purple color in green bell peppers or chili peppers but can also reduce overall yield and can ruin the flavor, too, causing the peppers to have a bitter taste.
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Sunscald
Sunscald also causes immature green peppers to have purple stripes in the early stages. It can also cause brown or discolored spots on the leaves, but it’s the developing fruits that will show the purple color. This is a condition caused by too much direct sunlight, which damages the delicate skin of immature peppers and the tender tissue beneath. Peppers need sunlight to thrive, but too much light can harm them, so make sure you provide some shade.
Too Much Iron
Too much iron in the soil can bind to the phosphorus and inhibit the pepper’s ability to absorb it. This essentially causes a phosphorus deficiency that causes your bell peppers to exhibit purple color patches.
Too Much or Too Little Water
Your pepper plant requires a healthy balance between water and sunlight – too much or too little of either can cause you problems. If you’ve been too generous with water, you’ll need to take steps to fix your overwatered peppers quickly. Consistent, moderate watering is key, where you let the soil dry out around an inch below the surface between waterings. Otherwise, you’ll see your pepper leaves turning yellow, black, or purple, and leave your plants open to disease and pest infestation.
How To Prevent Peppers from Turning Purple
If you don’t want your peppers to turn a purple color, start with checking your soil, given that one of the leading causes of purple peppers is too little phosphorus or too much iron. Well-balanced soil is the foundation of a healthy root system and, solid stems, plenty of leafy growth, and lots of fruit. You can use a simple soil test kit like this one to check the current nutrient profile of your soil to see if you need to make any amendments.
Make sure you rotate crops each year, too. Crop rotation is vital to good soil management. And make sure you don’t plant peppers where you planted other nightshades, like tomatoes or potatoes the previous year. Rotating crops makes sure that you don’t deplete specific nutrients from the soil.
Make the appropriate soil amendments to get good balance. Check out these recommendations for fertilizing peppers for every growing stage, or take a look at these organic fertilizers you can make at home.
Companion planting peppers is also a great way to keep your peppers healthy and prevent them turning purple or developing pests and diseases.
And, just as important as all the other tips: get the growing conditions right. Provide ample indirect sunlight, consistently warm temperatures, and moderate amounts of water.