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.
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In this article, we will show you how to diagnose your plant’s issue, and how to solve the problem!
So, why are my pepper plants turning yellow?
The main 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 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.
Now, let’s go through the most common causes, how to diagnose, and how to treat each of them.
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Nitrogen is an essential nutrient for vegetative 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 most common symptoms of this deficiency is yellowing leaves.
How Do I Know If My Plant Has a Nitrogen Deficiency?
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 shift 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. The leaves may fall off eventually, while the top leaves will remain green and healthy for longer.
The overall symptoms of Nitrogen deficiency are:
- Yellowing leaves, starting at the bottom of the plant and moving up
- Leaves falling off
- Stunted 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 garden. However, just using Miracle-Gro soil is not enough for your peppers to produce 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 necessary nutrients for your pepper plants.
You should fertilize your pepper plants about once per week (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 weaker, 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 strong. 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, make sure there is drainage. If all of the water is trapped in the pot, your roots can become water-logged and potentially develop rot. This also causes an inability for your plants to access oxygen which will 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 dehydrated (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 need to start watering a bit more frequently. Check-in 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, time to water!
You can also use a water meter like this one on Amazon. This device is affordable and tells you precisely the amount of water in your soil. It also measures pH levels to help reach the perfect level of acidity. Since some plants use more water than others, this is a more precise method for irrigating a diverse garden.
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 Iron are both important plant foods 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 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 deficiency.
Treating Other Nutrient Deficiencies
Treatment for Magnesium and Calcium deficiencies can be applied using sprays directly on the plant. These are only a temporary solution, while a long term solution is to use a richer soil from the beginning. Some people also use Epsom salt in their soil to promote healthier Magnesium uptake. Some gardeners 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 the most common cause for yellowing pepper plant leaves, fertilizing may not appear to solve your problem. One 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.
Type of Fertilizer
In addition to Fox Farm Fertilizer, we have also used this exact fertilizer for our pepper plants. It has a higher concentration of water-soluble Nitrogen, which may help the plants take in and use it more effectively.
I hope this article helps you diagnose why your pepper plants are turning yellow. Plants will give you all sorts of warning signals when they aren’t happy, and yellowing leaves is just another sign. Thankfully, there are easy solutions to this problem. Good luck!