Problem Identifier / Boron Deficiency in Plants

Boron Deficiency in Plants

Boron Deficiency In Lime Tree
Boron deficiency in a lime tree. PHOTO CREDIT Lesley Ingram,

Boron is one of the most important micronutrients essential for the health and growth of all plants. Boron is a component of the reproductive structures and the cell walls of the plant. When in the soil, this micronutrient is classified as mobile. This means it tends to move within the soil. Only small amounts of boron are required, making the even delivery of the micronutrient throughout the plant extremely important.

Most fertilizer blends with boron have difficulty achieving an even distribution of nutrients. Even though boron is a critical plant nutrient, it is the second micronutrient most often resulting in a deficiency, with zinc being the first. Boron is critical for a wide range of essential plant functions including maintenance, stability, and the functional and structural integrity of the biological membranes.

Boron is responsible for the movement of sugar resulting in energy for the areas of the plant requiring growth, the seed set and proper pollination. In legume crops, nitrogen nodulation and fixation are not effective without enough boron.

How Does a Boron Deficiency Affect the Quality of Your Plant?

A boron deficiency in plants has a major impact on the quality. This deficiency often results in:

  • The lushness of the plant decreases due to inhibited turgor
  • A decrease in fertility
  • The reduced production of pollen encourages sterility
  • Underdeveloped calyxes lead to symptoms including little brown spots
  • Reproductive and vegetative growth is affected at all stages
  • Slow plant growth
  • Stunted vegetation
  • Both female and male flower development becomes severely compromised

Symptoms of Boron Deficiency in Plants

Boron Deficiency Cannabis Plant
Boron deficiency in a cannabis plant.

The most common symptoms of a boron deficiency in plants include:

  • Twisted growth of the leaf tips
  • Curled or wrinkled new leaves
  • Death of the growing tips
  • Affected roots cause slow or unhealthy growth
  • Hollow or rough plant stems

A boron deficiency results in either a slowed or abnormal growth of the plant’s upper leaves. The tips of the leaves grow incorrectly, often resulting in twisted growth. New leaves become curled or wrinkled. The growing tips may eventually die. The roots of the plant can be impacted causing slow or unhealthy growth. Boron deficiencies are much more common at low levels of humidity or when the plants are underwatered.

New growth is impacted more than any other function often appearing as scorched or burnt areas. Both nitrogen and potassium are necessary for boron to be used by the plant.

Possible Confusion with Other Symptoms

Symptoms of a boron deficiency are often confused with the following:

  • Brown spots resulting from a lack of calcium can be confused with a boron deficiency
  • Issues with the plant roots can look like a boron deficiency
  • In tobacco plants, the twisted leaves from tobacco mosaic virus are similar

What Causes a Boron Deficiency?

The roots of the plant absorb boron, then use the transpiration stream to move throughout the plant. The uptake of boron is dependent on the active movement of water. If there is not enough movement, the result is a boron deficiency in plants. The other causes of a boron deficiency include:

  • Not enough boron in fertilizer or tap water
  • Dry or waterlogged soil
  • High humidity levels or pH
  • High levels of calcium
  • Tightly packed soil
  • Cold root zones
  • Inactive roots

How to Fix a Boron Deficiency in Plants

Boron Deficiency in Apples
Result of boron deficiency in apples.

Treatments for boron deficiencies include:

  • Remedy stressful conditions
  • Use high-quality soil containing boron
  • Stop using reverse osmosis or heavily filtered water
  • Adjust pH for the growing medium
  • Ensure the plants have adequate moisture
  • Use a humidifier in grow rooms
  • Flush the growing medium with pH water
  • Watch the plant for new growth

Stressful conditions can trigger a deficiency in boron. Once the stress is handled, the deficiency may disappear naturally. Quality soil containing a variety of nutrients is necessary to prevent a boron deficiency in plants. Giving plants specific types of water including reverse osmosis or heavily filtered can cause a deficiency. The tap water in most locations has more than enough boron for plants.

The number one reason for a boron deficiency is a high pH range. Plants are not able to absorb boron effectively at higher pH levels. If the level is extremely high, the symptoms of a deficiency can persist despite there being enough boron close to the roots of the plant. Plants will thrive in soil when the pH level is between 6.0 and 6.5 because the nutrient is absorbed by the roots much easier.

The best absorption rate for boron is under 6.5. Plant health is best established in hydro with a pH range between 5.5 and 6.2. The general recommendation is keeping the pH level between 5.5 and 6.5, but boron has different requirements. The roots of the plant have the best absorption rate when the pH is less than 6.2. When plants do not have enough moisture, boron is not absorbed efficiently.

Watering the plants or increasing the level of humidity to a minimum of 25 percent will treat a boron deficiency in plants. If the plants are in a grow room, a humidifier is often necessary to ensure boron absorption. Flushing the growing medium with pH water and nutrients are recommended for boron deficiencies. Older leaves with substantial damage will not recover.

Watch the plants for a few days to make certain new growth appears. This growth signifies the boron deficiency has been treated successfully.

How Long Does It Take for a Plant to Recover from a Boron Deficiency?

If the damage is too severe, the plants will most likely die. If not, the plants should recover within a few days. New growth is the first sign the boron deficiency is gone.

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