Blueberry Leaves Turning Yellow

Blueberries are perpetual flowering plants that are popular for their blue and purple fruits. They are part of the genus Vaccinium, which includes huckleberries, cranberries, bilberries and Madeira blueberries. These North American native plants are famous for their health benefits: They are believed to help with bone and heart health, diabetes management, and cancer prevention. However, blueberry plants are also prone to disease and discoloration, as discussed below.

Why are my blueberry leaves turning yellow?

Blueberry leaves can turn yellow because of chlorosis. This yellowing of the leaves is observed between the leaf veins, making the veins appear greener than the rest of the leaves. Chlorosis is commonly caused by an iron deficiency, and is considered a nutritional disorder rather than a disease. The most common reason for this disorder is improper soil pH.

Blueberries are acid-loving plants and need the correct soil pH to get their required nutrients from the soil. The ability of a plant to absorb nutrients becomes limited if the soil pH is not appropriate for the plant. Thus, the wrong soil pH could cause poor growth or even kill the plant. 

What should I do if my blueberry plant is suffering from chlorosis?

You should do a soil test if you suspect that your blueberry plant is suffering from chlorosis. This can be done with the help of your local extension center, or you may opt to buy a home kit and a pH meter. If the soil test indicates that your soil pH is very high, you should apply sulfur to the soil.  This lowers the pH and helps unlock soil nutrients, which can then be absorbed by the plant. 

Sulfur can be bought from garden retailers, but keep in mind that not all sulfur products will adjust the pH immediately after application. 

Can yellow leaves turn green again?

Yellow leaves are unlikely to turn green again unless the discoloration was caused by a nutritional deficiency. If the deficiency was corrected, the green color may return, but not in all instances. 

What is the best fertilizer for blueberry bushes?

Fertilizers that contain nitrogen in the form of urea or ammonium are considered the best for blueberry bushes. Ammonium sulfate is considered among the best nitrogen fertilizers for plants. 

What other nutrient deficiency causes yellow leaves?

Nitrogen deficiency can cause general yellowing in plants. The inner and older leaves tend to turn yellow before the others. The yellowing moves outward as it progresses and reaches younger leaves. 

Potassium deficiency makes leaf edges become bright yellow, although the inner leaf will stay green.  

Magnesium deficiency in blueberries is manifested by mature leaves that are pink on the edges but yellowish between the veins. If your soil test indicates that magnesium is low, add Epsom salt, or magnesium sulfate, at three ounces per plant to make up for the deficiency. 

What are the health benefits of blueberries?

  • They are the kings of antioxidant foods. 
  • They are rich in nutrients and low in calories. 
  • They reduce DNA damage, which could help protect against cancer and aging. 
  • They prevent cholesterol damage in your blood. 
  • They lower blood pressure. 
  • They prevent heart disease. 
  • They improve memory and maintain brain function. 
  • They contain bioactive compounds that may have anti-diabetic effects. 
  • They may help fight urinary tract infections. 
  • They may reduce muscle damage after rigid exercise. 

Types of blueberries 

There are at least four types of blueberries, as follows:

  • Southern highbush
  • Northern highbush
  • Lowbush 
  • Hybrid half-high
  • Rabbiteye 

When should I plant blueberry bushes?

Blueberry bushes may be planted in spring or late fall, except for those in cold regions. In areas where the temperature is -10 to -20 degrees Fahrenheit, or Zone 5, it is ideal to wait for early to mid-spring before planting blueberries. One-to-three-year-old plants are good choices, and make sure to buy only from reputable nurseries.

Conclusion 

Yellowing of blueberry leaves is attributed mainly to iron chlorosis, or a deficiency in iron. This is considered a nutritional disorder and not a disease. The main reason for the disorder is improper (or too high) soil pH, which prevents the plants from absorbing iron from the soil.

Image: istockphoto.com / A_Daria