Defining leaf tissue nutrient standards and nutrient disorder symptomology of greenhouse-grown spearmint (Mentha spicata L.)

Authors: CLADE, DANIELLE - North Carolina State University; VEAZIE, PATRICK - North Carolina State University; Boldt, Jennifer; HICKS, KRISTIN - North Carolina Department Of Agriculture & Consumer Services; DAVIS, JEANINE - North Carolina State University; JACKSON, BRIAN - North Carolina State University; WHIPKER, BRIAN - North Carolina State University

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/7/2025
Publication Date: 9/8/2025
Citation: Clade, D., Veazie, P., Boldt, J.K., Hicks, K., Davis, J., Jackson, B., Whipker, B. 2025. Defining leaf tissue nutrient standards and nutrient disorder symptomology of greenhouse-grown spearmint (Mentha spicata L.). HortScience. 60(10):1752–1762. https://doi.org/10.21273/HORTSCI18721-25.
DOI: https://doi.org/10.21273/HORTSCI18721-25

Interpretive Summary: The increased use of greenhouses for culinary herb production has led to a need to develop optimized production practices for each crop. This includes crop-specific fertilizer recommendations. Too little or too much of a plant-essential element can hinder plant growth and yield. Current nutrient guidelines exist for field-grown spearmint but not for greenhouse-grown plants. This research visually documented nutrient deficiency symptoms in the leaves of greenhouse-grown spearmint for 12 plant-essential elements. This research also defined deficient, low, sufficient, high, and excessive concentrations for each of the elements. This visual guide and the development of defined nutrient ranges for each element will help growers better identify when greenhouse-grown spearmint plants have too little or too much of an element in their leaves. This information will also guide growers on what corrective action to take, which will improve spearmint crop growth in greenhouses and reduce fertilizer use.

Technical Abstract: Spearmint (Mentha spicata L.) is a perennial herb popular for its distinct flavor and aroma. While traditionally grown outdoors as a field crop, controlled environment agriculture can provide an alternative method for producing spearmint. The objective of this study was to define foliar mineral nutrient interpretation ranges specific to greenhouse-grown spearmint by inducing and documenting individual nutrient disorders. Plants were cultivated in a hydroponic sand culture system and supplied with a modified Hoagland’s solution, where individual nutrients were either omitted or supplemented, while maintaining all others at consistent levels. As nutrient disorders became evident, symptoms were photographed and documented. Plant tissue was collected to measure plant dry mass and nutrient concentrations. Additional foliar tissue data were compiled with those from the present study to create a larger dataset containing 315 samples. Data were analyzed to define interpretation ranges for 12 essential nutrients using a hybrid meta-analysis Sufficiency Range Approach (SRA), which defined ranges for deficient, low, sufficient, high, and excessive tissue concentrations for each nutrient. The most representative distribution for each nutrient was selected based on the lowest Bayesian Information Criterion (BIC) value. Potassium, calcium, sulfur, boron, and copper were best modeled using a Normal distribution, while magnesium was best represented by a Gamma distribution. A Weibull distribution provided the best fit for nitrogen, phosphorus, iron, manganese, molybdenum, and zinc. These findings provide previously unavailable resources for diagnosing nutrient disorders and evaluating foliar nutrient analysis of greenhouse-grown spearmint.