What Makes Plants Turn Red?

Often, plants turn red during autumn as a sign of summer ending and the beginning of winter. To say the least, that’s the beautiful month of the year when leaves are red, gold, or yellow. 

But what about the rest of the year when your plant leaves turn red? What does it mean? 

If you have plants in your garden and notice this problem, start by finding out the root cause of the problem. It can be a nerve-racking experience if the plants begin to die from this issue. 

The main reason plants turn red is due to phosphorous deficiency in the soil. Other causes include; 

  • Cold weather 
  • Too much water 
  • Soil pH
  • Nutrients deficiency 

Before we conclude, you should know that some plants turn red due to a pigment known as anthocyanin. It is known to cause red leaves on grapes and onions and a blue color on blueberries and soy beans in black color. 

Some plants have this pigment, but since they produce it in small amounts, it doesn’t change the color of the leaves. Some plants have red leaves when they are young due to this pigment, but as they mature, they turn green. 

Why do plants turn red?

A simple understanding of the problem can help you determine the more straightforward way to solve it. For instance, if you are aware of nutrient deficiency in the soil, you will add nutrients to the soil as required. 

Let’s look at the different things that cause plants to turn red. 

Nutrient deficiency 

Most gardeners find it hard to diagnose a problem that is related to a deficiency in the soil. That’s because many reasons can cause the soil to have fewer nutrients. 

For example, if you purchase low-quality soil and use it to grow plants, it will never have sufficient nutrients. And even if you add extra nutrients, they may not stay in the soil as required. Another thing is that poor soil has poor drainage; thus, it makes it hard for nutrients to work when the soil doesn’t drain off excess water.  

So, how do you know that your plant lacks phosphorous? 

You can notice it when the leaves have purple/red tints or blots on their surface. Phosphorous is essential in plants because it regulates protein synthesis. Without protein synthesis regulation, the plants will have problems developing and growing. 

The plant will start having sugar level abnormalities, which can lead to the development of anthocyanin pigments in the leaves. You can quickly notice this problem in younger plants than in aging plants. 

Also, you can notice this deficiency when a plant lacks flowers or has a poor root system. That happens because phosphorous plays a big role in root and flower development. If there is a deficiency, then the plant will grow abnormally. 

How to treat phosphorous deficiency 

When your plants turn red, you find this is the problem. Then you have to solve it as early as possible. It’s easy; just purchase a fertilizer that contains phosphorous. 

The package has a specified amount of nitrogen, phosphorous, and potassium in the fertilizer. The manufacturers indicate it as NPK, and it’s in that order. 

You can also add compost or bone meal. Both of these have phosphorous and nitrogen. Using either compost or bone meal will add phosphorus to the soil and fix the problem. 

Cold weather

Cold weather is known to make plant leaves turn red. When plants experience harsh conditions, they go into survival mode. It happens so that they can prevent attacks from environmental conditions. 

When this happens, the plants turn red. It usually happens when temperatures drop below 40 degrees Fahrenheit. Most people call it spring foliage.

Too much water

Water is good when you apply it in the correct amount. Giving the plant more water makes it hard for the soil to have nutrients because it washes out the essential nutrients. Continued overwatering means fewer nutrients remain in the soil each time. 

So, you can solve this problem by knowing the amount of water your plants need. The best way to water is to ensure the soil is dry before you water. Then keep it moist and not wet. 


Giving the plant less water can make your plant leaves turn red. Since plants use water to transport food from the roots to other parts like leaves, the lack of water can result in phosphorus not moving from the roots to the leaves where it is required. 

So, ensure that you provide the soil with enough water to transport nutrients. You can create a watering schedule so that your plant has water. 

Soil pH

Soil pH is essential for the growth of a plant. pH is the acidity and alkalinity of a substance. Acidity starts from 1 being very acidic to 6 less acidic, then 7 is neutral. Alkaline starts above 7 to 14 being the most alkaline. 

 Most plants grow in alkaline soils, while some in acidic soil. A plant can grow in alkaline soil, but if the alkalinity levels increase, it will start to lack nutrients because the pH rise causes the plant to lose its ability to uptake nutrients. As a result, plants turn red because nutrients won’t move to other parts of the plant. 

The good thing is that you can test the soil pH using a test strip. You can purchase it from your local store. Once you find the problem, you can add compost. 

High-quality compost can reduce the acidity or alkalinity of the soil. It doesn’t matter which side the test read; if you add quality compost to the soil, it will level it, and the pH will return to normal. Why? Because compost is neutral and will neutralize the soil. 


If your plants turn red, the main problem you should consider is insufficient nutrients. It’s the leading and most common problem. If you notice it early, you can fix it with a simple addition of fertilizer, but if it’s late, you have to throw away the plant to ensure it doesn’t rot and bring pests and diseases to the garden. 

You must be observant when your plants are growing so that you can address any issues early on. If plant leaves turn red, find the problem from those listed above and fix it quickly. 

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