Solving Nutrient Burn in Hydroponic Crops


Solving Nutrient Burn in Hydroponic Crops

Hydroponics is the practice of growing plants in mediums other than soil. Instead, crops are fed by nutritious solutions in water solvents. Hydroponic cultivation works well for home growers as well as commercial farmers since it can be adapted to spaces of any size and requires less water than farming in soil.

However, without the nutrients typically found in soil, growers need to create an environment that allows crops to thrive. It is especially critical that plants get the right amount of nutrition. It is common for improperly nourished plants to develop nutrient toxicity, also known as nutrient burn.

Once the problem develops, growers must take steps to halt its progress, stop further damage, and prevent the symptoms from reoccurring.

Hydroponic Growers Control Crop Nutrients

Growing crops hydroponically begins with a setup plan. Setups can be simple enough for home planting or consist of vast, elaborate greenhouses. Most crops are cultivated indoors, but some farmers grow outdoors. Regardless of the plan, growers control plants’ nutrition.

The minimum a grower needs to begin is a container, growing media, a pH kit, and hydroponic nutrients, although commercial farmers use an expanded, more sophisticated version.

Experienced farmers adapt the type and amount of nutrients to plants’ needs, but beginners often make the mistake of overfeeding plants. Unless they correct the issue, crops are susceptible to nutrient burn.


What Is Nutrient Burn?


Regardless of how plants are grown, they can develop nutrient toxicity, commonly known as nutrient burn. It is a condition that occurs when plants are exposed to excessive nutrients. 


The condition can happen at any time during a growing cycle. It gets its name from the “burn marks” that appear on leaves, even though there has not been a fire. 


Factors That Contribute to Nutrient Burn


Nutrient burn is usually caused by creating a nutrient mix that is stronger than what is needed for each growth phase. Every grower will experience the issue at some time or another, but it is fixable, especially when caught early.

Beginners who use feeding instructions provided with setup materials may cause the problem by mixing solutions that are too strong for their needs. Experienced growers suggest reading instructions as the maximum nutrients needed since each crop has unique requirements.


Overwatering plants can lead to symptoms that mimic nutrient burn. Plants that need a dry period to function well, and access oxygen often show signs of distress if they are overwatered.


Using products like bloom boosters too often or adding them in concentrations that are too high will also create issues. These potent additives typically contain large quantities of B6, B3, and B2 as well as other valuable ingredients, but they must be used as directed and never over-applied.


How to Recognize Sick Plants


Signs of nutrient burn can vary, depending on which nutrients are being oversupplied. Regardless of the cause, the problem always affects leaves first, so growers must scrutinize leaves often. 


Nutrition burn can give leaf tips a yellow or brown “burnt” look. Brown spots may appear, and leaves often begin curling up. They may become crispy if the condition advances. Symptoms provide clues about which nutrients are causing the problem.


Too much nitrogen may cause leaves to curl downward, while excessive potassium usually results in brown spots at leaf edges. Nutrient burn may first affect new growth, but can also damage established bottom leaves. Plant growth can even begin to slow down since nutrition burn inhibits photosynthesis.   


It is important to note that other conditions can mimic nutrient burn. For example,


  • Potassium deficiency will discolor leaves


  • Light stress turns the tips of leaves yellow


  • pH fluctuations often discolor plant leaves


Why It Is Important to Prevent Nutrient Burn


Some growers believe that a certain amount of nutrient toxicity is acceptable and view it as a sign that plants are getting the maximum amount of nutrition. However, most farmers treat the condition as a severe threat that can impact their yield.


The reality is that providing excessive amounts of nutrients to increase harvests is like giving children extra vitamins to help them grow faster. The primary food that plants need to thrive is light, which they convert to energy via photosynthesis.


Leaves act like small solar panels that create energy used by the entire plant. When leaves are damaged or begin to fall off, plants do not have the energy for maximum growth. If nutrition burn gets out of control, it can cause a severe loss of leaf mass, which could have a significant impact on yields.


Growth Phases Can Determine Nutrition Needs


The simplest way to protect plants from nutrient burn is to understand what nutrition crops need during each growth phase. All crops need the following nutrients as they grow:


  • Calcium:  Critical for the development and growth of cell walls, which helps plants fight disease. Also necessary for nitrate absorption


  • Magnesium:  Ensures plants have a vibrant green color


  • Nitrogen:  Responsible for robust and healthy foliage and encourages the chlorophyll development that produces leaves’ green color


  • Sulfur:  Assists plants to grow seeds and resist disease. Also helps the production of vitamins, acids, and enzymes


  • Phosphorous:  Vital for root and flower growth and helps guard against environment stressors


  • Potassium:  Helps create healthy plants, particularly in the early stages and also encourages water retention


Crops grown in the soil absorb many of these nutrients naturally, but hydroponic plants must get nourishment from solutions. Growers often use a water nutrient delivery system that provides essential ingredients in the correct amounts needed for each phase of growth. For example, they may use specific products designed for newly cloned, flowering, and harvest-ready plants.


Preventing Plants from Suffering Nutrient Burn


The simplest way to deal with nutrient burn is to make sure it doesn’t happen. However, feeding plants grown in hydroponic systems can be more challenging than cultivating crops in soil. Different types of plants often react differently to the same conditions.


Environmental factors like humidity and temperature can also change how plants absorb water, which determines the correct nutrient solution required. Professionals caution newcomers to begin applying plant foods and liquid fertilizers slowly, which makes it easier to recognize early signs of nutrient toxicity.


According to experts, growers should also own a TDS meter. TDS meters can measure the number of dissolved solids in solutions. That makes it simple to measure nutrient level changes before and after altering solutions. 


The Steps Needed to Resolve Nutrient Burn


Hydroponic growers need to act at the first sign of nutrient burn, to prevent the loss of leaves and keep plants healthy. The first step is to reduce nutrient levels in the water reservoir.


The easiest way to reduce nutrients is to dilute the water. However, growers may also mix a new batch of nutrients using lower levels of each element. They can then replace the original water.


Once levels are lowered, plants will respond immediately. Leaves stop turning brown or yellow, and no new areas are affected. Damaged leaves cannot be restored, but the rest of the plant will stay healthy.


The process can be tricky, though. One plant may thrive with the number of nutrients that cause nutrient toxicity in another. That is why it is crucial to measure each crop’s needs. Experts recommend that growers begin feeding plants ½ their previous nutrients after changing water due to nutrient burn.


A TDS Meter can help prevent issues by allowing growers to monitor the nutrients in water regularly. The meter gauges how much of various elements are in a solution, which makes it easy to determine whether they are increasing or decreasing. Growers who notice meters showing a rise in nutrients can make changes before plants develop problems.


Pre-Harvest Flushing Is Critical


Pre-harvest flushing is another essential technique that professionals use to lower nutrient levels. It is a form of detox for plants that is done sometime before crops are harvested. It is necessary because any minerals plants do use will remain in feeding solutions.


Flushing allows plants to use up the last remaining nutrients, which improves the taste of consumable products. Hydroponic growers can flush nutrients as late as a few days before harvest. The process usually involves flushing the medium and then the plants. 


  • Flushing the Medium: This is a simple process for hydroponic growers. They just dispose of the current solution in their reservoir and replace it with one that has less salt. If growers are using mediums like coco coir or Rockwood cubes, they should pour the new solution through the medium to clear minerals.


  • Flushing the Plants: As plants grow, minerals build up in their tissues. If excess minerals are not flushed, they can lead to problems like a bad smell, disagreeable flavor, or even plant damage. Flushing ensures the purest possible crop. The simplest method is to provide plants with plain water in the days before harvest, forcing them to use excess elements.


It is common for hydroponic crops to develop nutrient burn caused by feeding plants too many nutrients. Leaves on affected plants become discolored and can die, reducing the leaf mass that is necessary for good health. Growers can prevent the problem by using the correct nutrients for each phase of growth. Nutrient burn in hydroponic plants can be resolved by diluting water in the feeding solution or replacing it with a solution that has lower nutrient levels.