How Suboptimal Fertilization Affects Yield

Fertilizer is a crucial component of crop production, but simply adding fertilizer to the system is no guarantee a crop will get the nutrients it needs. Inadequate nutrient availability, nutrient incompatibility, and subpar nutrient formulations can result in under-fertilized plants, also known as suboptimal fertilization.

Without the right nutrients in the right concentrations and ratios, plants cannot achieve optimal yields or maximize crop quality. For cannabis, suboptimal fertilization can also impact cannabinoid profiles and concentrations.

Consequences of suboptimal fertilization

In one study, researchers tested the consequences of suboptimal fertilization in cannabis by inducing nutrient deficiencies. They found that imbalances of even a single essential nutrient can substantially impact growth and reduce yields and quality, especially when the imbalances occur during flowering. Floral yields were reduced by 33‒72% in all but two nutrient-deficient treatments.[1]

Yield reductions of this kind are explained by Liebig’s law of the minimum, which states that plant development is limited by the scarcest essential nutrient. So even when a plant is fed sufficient quantities of all essential nutrients except one, it will not reach its full potential in yield or in quality.

In addition to reduced yields, nutrient deficiencies can cause the following problems:

  • Impaired plant growth and development: Suboptimal fertilization frequently prevents plants from reaching their expected size and impairs their overall health.
  • Underdeveloped root system: It can also compromise root growth, limiting plant access to water and nutrients.
  • Delayed maturity: Suboptimal fertilization may even delay crop maturity, prolonging the time to harvest without increasing yield or crop quality in the process.
  • Increased susceptibility to pests and diseases: Weakened plants are more vulnerable to pathogens, which can result in additional yield losses.

Causes of suboptimal fertilization

Suboptimal fertilization occurs for several reasons.

The most obvious cause is not providing enough fertilizer. When cultivated indoors under ideal conditions, cannabis is a prolific grower requiring a lot of nutrients.[2] While providing excessive fertilizer may result in a different problem, toxicity, one study found that increasing fertilizer rates diluted cannabinoids such as THC, THCA and CBGA.[3] A healthy balance in nutrient applications—not too little or too much, hitting the sweet spot—is required.

Another study found that cannabis fertilized with 100 mg/L of phosphorus during the vegetative phase performed similar to cannabis fertilized with only 30 mg/L. Growers often fertilize plants with high rates of phosphorus—up to 200 mg/L during flowering—in the mistaken belief that more is better when it comes to flower development, but there is little evidence to support it.[4]

High phosphorus levels can also lock out nutrients like iron, zinc, magnesium, calcium and copper. This is called nutrient antagonism; it occurs when too much of one nutrient prevents another nutrient from being available for absorption. The growing medium’s pH also influences nutrient availability, so it is important to make sure that it stays in balance too. For example, iron can be locked out if the pH is too high.[5]


Choose a complete fertilizer line

To avoid suboptimal fertilization, provide the right nutrients in the right concentrations and ratios at the right times in the cannabis life cycle.

The simplest way to achieve this is by sticking with one integrated line of fertilizers whose components are already formulated to work in tandem. That way you’re not at risk of under- or over-fertilizing the crop or of supplying the wrong nutrient ratios, thereby causing suboptimal fertilization.

That’s why Emerald Harvest’s product line is simple and compact, consisting of premium base nutrients and supplements designed to work together, so you can grow the biggest yields and highest-possible quality.

The Emerald Harvest Team

[1] Llewellyn, David, Scott Golem, A. Maxwell P. Jones, and Youbin Zheng. 2023. “Foliar Symptomology, Nutrient Content, Yield, and Secondary Metabolite Variability of Cannabis Grown Hydroponically with Different Single-Element Nutrient Deficiencies” Plants 12, no. 3: 422.

[2] Ibid.

[3] Caplan, Deron, Mike Dixon, and Youbin Zheng. “Optimal Rate of Organic Fertilizer during the Flowering Stage for Cannabis Grown in Two Coir-based Substrates”, HortScience horts 52, 12 (2017): 1796-1803, accessed May 16, 2024,

[4] Bevan, Lewys, Max Jones and Youbin Zheng. “Optimisation of Nitrogen, Phosphorus, and Potassium for Soilless Production of Cannabis sativa in the Flowering Stage Using Response Surface Analysis”, Front. Plant. Sci. 12 (2021):

[5] Whipker, Brian E, Paul Cockson, Patrick Veazie, David Logan, Dylan Kidd, and W. Garrett Owen. 2021. “3 Tips to Avoid Nutrient Lockout.” Cannabis Business Times, January 2021.

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