One of the most common issues when growing peppers is a discoloration of the leaves. We see it commonly asked: Why are my pepper plants turning yellow? There are a few possible reasons for yellowing pepper plant leaves, and it is almost always fixable.
In this article, we will show you how to diagnose your plant’s issue, and how to solve the problem!
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So, why are my pepper plants turning yellow?
One common cause of yellowing pepper plant leaves is a nutrient deficiency. The most important nutrients to your pepper plant are nitrogen, phosphorus, and potassium. There is also a need for magnesium, calcium and other trace elements, but these are less commonly a problem.
Another possible cause of pepper plants turning yellow is inconsistent watering. Over-watering can cause stress to your pepper plants, causing leaves to turn yellow, stunted growth, and lower pepper production.
Finally, extreme temperatures can cause pepper leaves to die and fall off, turning yellow. This is especially common in cold weather, below 50°F.
Now, let’s go through the most common causes, how to diagnose, and how to treat each of them.
Nitrogen is an essential nutrient for all vegetative plant growth. It is what helps grow big, strong plants with lots of healthy green leaves. Without enough nitrogen, your pepper plants will suffer in a number of ways. One of the first symptoms of this deficiency is yellowing leaves.
Do My Peppers Need Nitrogen?
There is an easy way to know if your plant needs more nitrogen. The yellowing leaves will start at the bottom of your pepper plant, and move upwards over time.
The reason for this tell-tale sign is because nitrogen is a “mobile nutrient,” meaning that your plants can move nitrogen from one part of the plant to another.
When your plant is running low on nitrogen, it will begin to move the remaining nutrient from the older leaves up toward the newer growth. You will see that your larger, older leaves at the bottom of the plant will turn yellow first.
Without treatment, the yellow leaves may fall off eventually, while the top leaves will remain green for longer.
- Yellowing leaves, starting at the bottom of the plant and moving up
- Leaves falling off
- Stunted plant growth
- Flowers falling off
Thankfully, adding nitrogen back to your plant can solve this problem quickly.
How to Add Nitrogen To Pepper Plants
The easiest way to add nitrogen to your plants is to fertilize! Fertilizer is almost always necessary for an ideal pepper garden, especially in potted plants. However, just using Miracle-Gro soil may not enough for your peppers to grow at their best.
Fox Farm makes a great trio of fertilizers that you can buy on Amazon. These fertilizers are designed to work together and provide accessible nutrients for your pepper plants.
Refer to your specific fertilizer for frequency instructions. Generally, you should fertilize your peppers once every week or two (depending on the type of fertilizer) in order to keep your plants healthy and happy throughout the season.
Some fertilizers are stronger, while others are slow-release, so refer to the packaging on yours to get an idea of frequency.
Using a 5-5-5 (or even lower) fertilizer will provide plenty of nitrogen to keep your plants from turning yellow. These three numbers indicate the amount of nitrogen, phosphate, and potassium respectively.
Starting a fertilizing regimen will undoubtedly help your plants grow stronger. However, leaves that have already turned yellow will not turn back to green. This is nothing to worry about.
Learn more about how we fertilize our pepper plants in our article here.
Watering too much or too little can cause major stress to your plant. Water is an essential ingredient for your plant’s success, but getting the amount right is important.
With pepper plants, you want to water just enough to keep the soil moist, but not soaking wet. If you are growing in planter pots or in the ground, make sure there is good drainage. If all of the water is trapped in the root system, your roots can become water-logged and potentially develop rot.
Poor drainage also causes an inability for your plants to access oxygen which can cause serious problems. This includes yellowing leaves, but will also lead to overall smaller plants and less productivity.
Note: Watering too much is more commonly the issue. Peppers can tolerate being dried out and will give you a signal to water if they are too dry (wilted leaves). Try to err on the side of dry rather than wet!
On the other hand, pepper plants don’t like to be completely dried out. If you notice that your leaves are wilting before every watering, you may want to start watering a bit more frequently. For example, in hotter weather peppers require more water.
Check on your peppers once a day and feel the soil for moisture. If you are growing in pots, lift the pot to feel its weight. You will get a sense of how heavy a well-watered plant feels, and how a dried out plant feels. If it is feeling light, probably time to water!
You can also use a water meter like this one on Amazon. This device is affordable and tells you the approximate amount of water in your soil. It also measures pH levels (though how well it does this is debated) to help reach the right acidity. Since some plants use more water than others, this is a more precise method for irrigating a diverse garden.
Learn more about watering pepper plants in our dedicated article here.
Cold Weather and Dying Leaves
Another common cause of yellow pepper plant leaves is abnormally cold weather. Peppers come from a naturally warm and arid climate. As the growing season comes to a close and fall is setting in, your plants will stress with the temperature changes.
If nighttime temperatures dip below 50°F, your pepper leaves may begin to turn yellow and fall off. This is a natural response by the plant to enter a hibernation state. If temperatures drop below 40°F, you will see a significant drop in leaves, and below 32°F will likely kill a pepper plant.
If temperature is to blame, the yellow leaves will be randomly spread around the pepper plants, with no particular locations more affected than others. This is one way to distinguish this culprit from a nutrient deficiency.
Keep an eye on overnight temperatures in your area to determine if cold weather may be to blame for your pepper’s yellow leaves.
Other Nutrient Deficiencies
While nitrogen is the most common deficiency, it is possible that your pepper plants are turning yellow because of another. Magnesium and calcium are both important plant nutrients that may be lacking.
Magnesium is another nutrient that is required for healthy pepper plants. While it is less common in soil-based gardening, it can still occur. Leaves will turn yellow, starting at the bottom of the plant (just like nitrogen). However, if you look closely, you will notice that the veins of your leaves will remain green, while the flesh will be pale yellow. This is known as Chlorosis, and is the main way to distinguish a magnesium deficiency from nitrogen.
Calcium plays a vital role in building strong cell walls in plants and fruiting bodies. It also helps plants better absorb other nutrients. According to this study, it also aids in expanding the main root systems of plants. It is less common to see this deficiency, but it is marked by curled leaves and often brown spots on the leaves.
See here for more example images of calcium deficiencies.
Treating Other Nutrient Deficiencies
Treatment for magnesium and calcium deficiencies can be applied using cal-mag sprays directly on the plant foliage. These are only a temporary solution, while a long term solution is to use a richer soil in the correct pH range (5.8-6.2) from the beginning.
Some people also use 100% Epsom salt in their soil to promote healthier magnesium uptake. You can also crush eggshells or use crab shell nutrients to provide calcium and magnesium to the soil.
Why Are My Leaves Yellow, Even With Fertilizer?
While nutrient deficiency is a common cause for yellowing pepper plant leaves, fertilizing may not appear to solve your problem. If you have determined that it is not caused by one of the issues listed above, what could be the problem?
One potential cause is that once leaves have turned yellow, fertilizer will not change them back to green. Fertilizing will help new growth remain healthy, but yellowed leaves will remain yellow. Another possible cause is water stress.
If you have been fertilizing since the beginning, and are still seeing yellow leaves, then your plants may have difficulty using the nutrients. Different fertilizers contain different types of nitrogen and other nutrients. Some are water-soluble, while others are not.
If your soil’s pH is too acidic or overly alkaline, your pepper plants will not be able to use certain nutrients in the soil, even if they are present. Each year, you can send a soil sample away for a professional soil test. This will tell you the exact pH of your soil and how to amend it to reach ideal nutrient and pH levels.
Type of Fertilizer
In addition to FoxFarm fertilizer, we will often supplement with this fertilizer for our pepper plants. It has a natural source of water-soluble nitrogen, which may help the plants take in and use it more effectively. Neptune’s Harvest fertilizers work wonders as a nutrient supplement.
I hope this article helps you diagnose why your pepper plants are turning yellow. Pepper plants will give you all sorts of warning signals when they are unhappy, and yellowing leaves is just another sign. Thankfully, there are easy solutions to this problem. Good luck!