How to spot nutrient deficiencies in your plants

To produce the best yields and highest quality, your crops need all of the essential plant nutrients. Even if adequate amounts of the primary nutrients – nitrogen, phosphorous and potassium – are available, a shortage of one or more secondary or micronutrients could limit yields and reduce the quality of your crop. Depending on the soil in your region, your plants could face serious deficiencies in primary, secondary and micronutrients.

How do you know if your plants are deficient in nutrients? Here’s how to spot the symptoms:


Phosphorus deficiency is difficult to diagnose because abnormalities, such as purple leaf color, don't show up until the deficiency is severe. Mild cases may darken the green leaf color due to a surplus of nitrogen. Other symptoms include slow growth, delayed maturity, poor tillering and low seed yields.


Sulphur deficiency symptoms usually begin in new growth because sulfur is not easily translocated in the plant. Look for general chlorosis of leaves, stunted growth and low seed yields. Sulfur deficiency in canola may also cause low oil content in seeds and produce deformed cup-shaped leaves that take on a reddish-bronze color.


As one of the primary nutrients, nitrogen is vital to the health of your plants. Symptoms of nitrogen deficiency include general chlorosis (leaves are pale, yellow or yellow-white) of older leaves, stunted growth and low protein content in foliage or seeds.


Potassium is highly mobile in plants, so deficiencies appear on old growth first. Look for general chlorosis intensifying to scorched edges and interveinal areas of the older leaves. Other symptoms include poor stem strength which may lead to lodging and low bushel weight of cereals due to shriveled seeds.


Visible symptoms of boron deficiency are not common. However, symptoms may appear on new growth – as boron is immobile in plants. Leaves and stems may thicken and become brittle while forages and canola may have reddish or bronze discoloration or yellow mottling. Also, look for poor fertilization and seed or fruit set, poor growth or death of terminal buds and shortened internodes.


Chloride deficiency in cereals is sometimes manifested as "physiological leaf spot" which resembles a tan spot. Other symptoms may include wilting followed by chlorosis (leaves are pale, yellow or yellow-white), bronzing of leaves, yield loss and greater disease incidence.


Copper is immobile in plants, so deficiencies are seen on new growth first. Seriously deficient cereal plants turn light green, with dried and twisted leaf tips similar to frost damage. Mild deficiencies may result in low test weight and higher levels of disease, especially melanosis (blackening of the seed heads). Copper deficiency may also cause ergot in cereals.


Symptoms of iron deficiency are not common in most field crops but may occur in high pH/calcareous soils. Iron deficiency is exhibited as distinct interveinal chlorosis of the upper leaves. Veins remain green with light green, yellow or even whitish interveinal tissue. Iron-deficient plants are generally spindly and stunted.


Manganese deficiency is most common in soils with high pH or organic matter. Manganese is an immobile nutrient, so symptoms appear first on new leaves. In cereals, the new leaves become chlorotic, creating a striped-leaf effect. Gray specks may occur in cereals. Broadleaf crops show some mottling or interveinal chlorosis similar to iron deficiency.


Symptoms of zinc deficiency commonly appear as stunted plants with shortened internodes and small leaves. Severe deficiency can result in "rosetting" of terminal leaves. Also look for interveinal chlorosis and/or mottling of leaves and delayed maturity. Zinc deficiency is most common in high pH soils, soils with low zinc levels and soils with high phosphorus levels.

All the nutrients your plants need, in one granule

Every granule of Rainbow Plant Food is a complete package of nutrients that are uniform in size, shape and weight, so they spread evenly to maximize distribution. These granules also deliver the proper nutrient amount within the all-important root zone. Rainbow gives your crops just the right amount of nutrients needed to thrive and bring you strong returns.

Rainbow Plant Food is available in a variety of grades and formulations designed to meet the nutritional needs of your crop.

For more information about micronutrient deficiencies, click here.

For Rainbow Plant Food application recommendations, click here.

For Rainbow Plant Food Grading and Analysis, click here.

For questions or comments, tweet us @Rainbow_Plant.