How to Identify and Prevent Nutrient Deficiencies in Cannabis

by | Mar 2, 2021

Written by Kristina Etter

Kristina is a digital content creator and designer. She has a talent for creating engaging and informative content that resonates with our professional audience. Kristina’s passion for the cannabis industry stems from her belief that it has the potential to revolutionize the world in many ways, and has a personal testimony of cannabis success.

As with most crops, maintaining the perfect environment for the plants is the essential function for farmers and growers. Whether you’re talking about cannabis or cabbage, ruderalis, or rutabaga, all plants need a particular recipe of sunlight, water, and nutrients to produce quality fruits. An imbalance in the delicate ratio of these vital ingredients can result in nutrient deficiencies that can sicken your plants, reduce your yields, or even kill your entire crop.

Naturally, preventing nutrient deficiencies in cannabis starts with recognizing and identifying the problem and the know-how to correct it. However, as perfectly portrayed in the first season of “Growing Belushi” on Discovery, Jim Belushi sprayed his plants with neem oil, is distracted, and accidentally leaves with the lights on, ultimately burning the crop.

Although neem is an organic pesticide, not a vital nutrient, this is an excellent example of the fact that humans make mistakes, so many commercial growers are turning to automation technology to avoid critical errors.

Identifying Nutrient Deficiencies in Cannabis

The first step in preventing nutrient deficiencies in cannabis is learning to identify them and their causes. The nutrients which are critical for cannabis include Nitrogen (NO2), Phosphorus (P), Potassium (K), and Magnesium (Mg). Let’s explore what deficiencies look like in each of these elements.

Nitrogen (NO2)

One of the most essential nutrients for healthy plant development, nitrogen fuels the production of enzymes, proteins, and chlorophyll. Several factors can contribute to nitrogen deficiency including, small containers, poor soil, lack of fertilization, a pH imbalance, or even certain pests.

Because nitrogen is responsible for producing chlorophyll, the chemical which makes plants green, the most obvious sign of a nitrogen deficiency is the yellowing of leaves. Besides yellowing, other signs and symptoms of a nitrogen deficiency include:

  • Short, underdeveloped plants
  • A decrease in yields during the flowering stage
  • Wilting, withering, and dying

It’s important to note that plants do not require nitrogen during the last three weeks of flowering, and yellowing and shedding during this time is a natural and expected outcome.

Phosphorus (P)

While phosphorus is required at all stages of the plant’s lifecycle, it is critical for root development and bud growth. However, too much phosphorus can result in over-feeding plants, as well, so it’s imperative to ensure proper dosing of the nutrient.

A phosphorus imbalance can result in the following symptoms:

  • Poor root development
  • Small, blue-green leaves
  • Leaves may turn purplish during flowering
  • Limited bud growth
  • Sickly plants that are more vulnerable to pests

So, what causes a phosphorus deficiency? Multiple conditions contribute to the problem, including low, waterlogged soil, a pH imbalance, too much or too little fertilization.

Potassium (K)

Potassium is essential for plant health. Potassium performs several critical functions in plants, such as providing energy, improving growth in the plant itself, as well as the roots, regulating transpiration or water evaporation, and helping to create chlorophyll, sugars, and starches.

There are two main culprits of a potassium deficiency in cannabis: poor soil and too much fertilizer.

Potassium deficiency symptoms may look similar to a nitrogen deficiency and also include:

  • Leaf deterioration
  • Rust-colored spots
  • Brown leaves
  • Brittle stems during flowering

Magnesium (Mg)

Magnesium helps plants develop healthy veins and leaves and helps break down enzymes and produce chlorophyll. Reasonably common in commercial cannabis cultivation because certain indoor growing conditions can affect how the plants absorb the mineral.

Growers should look for the following symptoms to identify a magnesium deficiency:

  • Yellowing between veins on the low to mid-level leaves
  • Dotted rust spots throughout
  • Edges of leaves start to curl
  • Leaves start to pale or look white

Causes of magnesium deficiency include poor soil, over-fertilization, acidic soils, or high calcium levels.

How Automation Technology Helps Prevent Nutrient Deficiencies

Growing six plants for personal use looks much different than growing 6,000 plants for commercial use. While most cannabis growers started outgrowing for themselves, adapting and scaling to accommodate a rapidly growing retail market comes with a whole different set of challenges. Commercial grow operations require skilled, competent staff to nurture and care for the delicate crop. But as Jim Belushi taught us – err is human, and one tiny mistake can lead to catastrophic outcomes.

The answer many commercial growers are seeking lies in the development of automation technology. Automating nutrient application eliminates the variable of human error.

With a crop where consistency is critical, closely monitoring conditions within the grow operation and making the necessary adjustments separate good yields from great yields. To ensure proper nutrient dosing every time, growers have three basic requirements for automation:

  • Dosing System – a method to dilute the various nutrients to proper strength and deliver them into the irrigation system.
  • Application System – the process by which the solution is uniformly delivered to the root zone when needed.
  • Repeatable Method – for the sake of consistency, the dosing system and application system functions require repeatability for optimal plant health and efficient operations.

Growlink and the Benefits of Automation

In a commercial environment, optimizing efficiencies and reducing costs is a balancing act for producing a quality product at the lowest possible price. Automation acts as a catalyst for optimizing labor, freeing up your employees to focus on value-added manual work while the system handles tedious, repeatable tasks for consistent, accurate results.

Integrated fertigation systems allow operations to monitor and control their crops with little manual intervention. With a dashboard that provides real-time analytics and detailed reports, growers can easily visualize sensor data, including temperature, humidity, vapor pressure deficit, carbon dioxide levels, photosynthetic active radiation, or PAR.

Nutrient dosing systems like those offered by Growlink allow cultivation operations to:

  • Adjust pH regularly, based on plant requirements
  • Change pH and type of water
  • Monitor and record dosing details
  • Prevent crop shock
  • Reduce losses and boost yields

If you’re interested in taking the guesswork out of optimizing your cannabis operation, contact Growlink today to learn more about their automated nutrient dosing system.


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