How to Identify Nutrient Deficiencies

Nutrient deficiencies prevent plants from reaching their maximum genetic potential in terms of both quantity (yields) and quality (color, flavor, fragrance and potency).

As we discussed in our blog post on suboptimal fertilization, a deficiency in just one essential plant nutrient can seriously impair plant growth and health. Therefore, it is crucial to be able to spot the first signs of a deficiency.

In this blog post, we’ll discuss the symptoms that indicate a nutrient deficiency and how to determine which nutrient is deficient.

Symptoms of nutrient deficiencies

Five types of symptoms are commonly associated with nutrient deficiencies:

  • Stunted growth can occur when a plant lacks sufficient nutrients involved in processes such as stem elongation, photosynthesis and protein synthesis, resulting in plants that are small in stature.
  • Chlorosis, or yellowing, can range from localized white or yellow spotting to the entire plant appearing light green or yellow. Chlorosis occurs when plants are deficient in nutrients necessary for photosynthesis or chlorophyll production.[1]
  • Interveinal chlorosis occurs between the veins in the leaf tissue, while the veins themselves remain green. Interveinal chlorosis happens when plants are deficient in boron, iron, magnesium, manganese, nickel or zinc.
  • Purple-red discoloration coloring of the plant stems and leaves is due to abnormally high levels of anthocyanin, which can be caused by a phosphorus deficiency.
  • Necrosis is when plant tissue browns and dies.

Once a nutrient-deficiency symptom is identified, growers can look at the location of the symptom to determine if the deficiency is caused by a mobile or immobile nutrient.

Mobile nutrients (i.e., chlorine, magnesium, molybdenum, nitrogen, phosphorus and potassium) can move from older leaves to younger parts of the plant when nutrients are inadequate. Symptoms indicating deficiencies of these nutrients first appear in the older or lower leaves and then generalize or localize (Figure 1).

Figure 1. If older or lower leaves are affected, follow this flow chart to determine which mobile nutrient is deficient. Image source: McCauley, Ann, Clain Jones, and Jeff Jacobsen. 2011. “Plant Nutrient Functions and Deficiency and Toxicity Symptoms.” Accessed July 1, 2024. https://apps.msuextension.org/publications/pub.html?sku=4449-9

Immobile nutrients (i.e., boron, calcium, copper, iron, manganese, nickel, sulfur and zinc) cannot move from one part of the plant to another, so when a deficiency presents itself, it is localized in the younger or upper leaves (Figure 2). Zinc, which is only somewhat immobile, is an exception; symptoms of zinc deficiency manifest in the middle leaves before affecting older and younger leaves.

Figure 2. If new or younger leaves are affected, or symptoms are localized, follow this flow chart to determine which immobile nutrient is deficient. Image source: McCauley, Ann, Clain Jones, and Jeff Jacobsen. 2011. “Plant Nutrient Functions and Deficiency and Toxicity Symptoms.” Accessed July 1, 2024. https://apps.msuextension.org/publications/pub.html?sku=4449-9

Identifying essential nutrient deficiencies

Here we list the essential plant nutrients in alphabetical order, as well as the symptoms of deficiency for each.[2] The images show the initial (top), intermediate (middle) and advanced (bottom) stages of deficiency.[3]

Boron (micronutrient, immobile):

  • Lightly stunted stem and root tips (initial stage).
  • Distorted growth of young leaves and growing tips.
  • Narrower and smaller leaflet bases.
  • Necrotic spots between veins (advanced stage).
  • Inwardly curled leaves with pale-brown coloration.
  • Rust-colored leaves.
  • Swollen root tips.
  • Wilting throughout the entire plant due to the death of root tips and subsequent loss of root biomass.

Calcium (secondary macronutrient, immobile):

  • Stunted growth.
  • Narrow leaflets with interveinal chlorosis.
  • Irregular leaf geometries and orientations.
  • Yellow leaves with necrotic growing tips (advanced stage).
  • Smaller root tips.

Copper (micronutrient, immobile):

  • Minor stunting followed by young leaf distortion around leaflet bases.
  • Wilted shoots and young leaves.
  • Slight chlorosis around the leaflet.
  • Distorted and narrowed leaflet base, with marginal interveinal chlorosis.
  • Curled leaves.
  • Dark green tips and margins.
  • Limp young leaves.

Iron (micronutrient, immobile):

  • Upper foliage deficiencies.
  • Symptomatic growing tips and newly emerging leaves.[4]
  • Slowed growth.
  • Marginally yellowed leaflets, centered around the base of the leaf.
  • Interveinal chlorosis of young leaves (advanced stage).
  • Dark coloration of mid and lower foliage (advanced stage).
  • Necrotic leaves that drop off.

[4] Mainly at the end of the leaf tip.

Magnesium (secondary macronutrient, mobile):

  • Interveinal chlorosis and brown spotted lower and older leaves (early stage).
  • Sharp interveinal chlorosis.[5]
  • Loss of brown-tipped, curled and dried older leaves.

[5] Some regions will be necrotic in the advanced stages.

Manganese (micronutrient, immobile):

  • Yellow-netted interveinal chlorosis of upper and central foliage.
  • Symptoms in young leaves first, then older leaves.
  • Midrib chlorosis of the leaflets that spreads outward toward the leaf margin.
  • Small tan necrotic leaf regions (advanced stage).
  • Leaf loss.

Molybdenum (micronutrient, immobile): This deficiency is difficult to identify, but the main signs are twisted leaves and hindered root growth.

Nitrogen (primary macronutrient, mobile):

  • Slight stunting.
  • Yellowed or pale lower foliage.[6]
  • Curled up tips and edges.
  • Fully yellowed or brownish leaves.[7]

[6] Yellowing will become more severe and advance from the bottom-most leaves to the middle foliage.

[7] Leaves will gradually become necrotic abscised in the late stages.

Phosphorus (primary macronutrient, mobile):

  • Slight stunting.
  • Slowed lateral growth.
  • Purple-colored petioles.
  • Olive-green, irregularly patterned spots on lower and older leaves.[8]
  • Curled and dropping leaves.

[8] These will develop into larger spots that appear sunken and damp with marginal necrosis. In advanced stages, yellowing leaves will become severely spotted and may develop large necrotic portions.

Potassium (primary macronutrient, mobile):

  • Leaf margin chlorosis on the lower and older foliage that turns pale (initial stage).
  • Brittle and weak stems.
  • Yellowing toward the midrib.
  • Yellow leaflet margin (advanced stage).
  • Greening and loss of leaves (advanced stage).

Sulfur (secondary macronutrient, immobile):

  • Lime green to yellow foliage, mainly in the middle of the plant and at the base of the leaflets (early stage).
  • Intense yellowing of new growth.
  • Purple-streaked stems that turn woody.
  • Yellowed leaves, particularly around the midrib and base of the leaflets (advanced stage).
  • Darkened and bent down leaf tips.

Zinc (micronutrient, immobile):

  • Yellowed new foliage (initial stage).
  • Yellowed leaf margins and leaflets.
  • Interveinal chlorosis.
  • Shortened growing tips.
  • Tanned and irregularly shaped necrotic regions along the leaf margin.
  • Burned leaf tips.

Conclusion

Prevention is the best medicine when it comes to nutrient deficiencies.

Routine tissue sampling of the most recent mature leaves can reveal if deficiencies are developing before symptoms appear.[9]

If tissue sampling is impossible, plants must be carefully observed on a daily basis, so that corrective measures can be taken as soon as possible.

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Emerald Harvest Team

[1] Chlorophyll is the green leaf pigment involved in photosynthesis.

[2] We do not list chlorine and nickel, as deficiencies of these micronutrients are extraordinarily rare.

[3] Cockson, Paul, Hunter Landis, Turner Smith, Kristin Hicks, and Brian E. Whipker. 2019. “Characterization of Nutrient Disorders of Cannabis sativa.” Applied Sciences 9 (20): 4432. https://doi.org/10.3390/app9204432.

[9]Cockson, Paul, Hunter Landis, Turner Smith, Kristin Hicks, and Brian E. Whipker. 2019. “Characterization of Nutrient Disorders of Cannabis sativa.” Applied Sciences 9 (20): 4432. https://doi.org/10.3390/app9204432.

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