Plants can become nutrient deficient if they do not receive adequate chemical elements for plant growth and development. These may arise from inadequate essential nutrient levels in the soil or growing media, whether the plant is outside in the landscape or indoor in a pot. However many factors such as inadequate light conditions, plant stress, incidence of pest, and inadequate soil conditions can prevent plant root uptake of nutrients and can be mistaken for a nutrient deficiency condition. It may be difficult to determine if your plant has a nutrient deficiency problem without analyzing the plant foliage for nutrient content.
You can get an idea if your plant is experience a nutrient deficiency condition by conducting a visual diagnosis for common essential nutrient deficiencies symptoms. For this, you will need to identify if the abnormal condition or nutrient deficiency symptom, which could be yellowing, necrosis, spottiness, etc., is occurring on the old leaves (schematic 1) verses the new leaves (schematic 2).
Using the visual diagnosis schematic for symptoms on old leaves, if the deficiency is occurring on old leaves but also exhibiting symptoms on the entire plant with the plant having a light green appearance or lower leaves yellowing that are drying and turning brown, it is usually an indication of nitrogen deficiency. Nutrients deficiencies for phosphorus, magnesium and potassium are usually expressed in old plant leaves as seen in the old leaves schematic.
Symptoms that appear on new plant leaves that are differentiated by distorted leaves that maybe showing necrosis and depending on whether terminal buds dies would lead to a visual diagnosis of either boron, calcium or copper. On the other hand, symptoms that appears on new leaves that are differentiated by chlorotic leaves that maybe spreading to entire plant or exhibiting intervenial chlorosis, depending on shortening of the plant stem and the presence of necrotic spots would lead to a visual diagnosis for sulfur, zinc, iron, or manganese.
Amy L. Shober and Geoffrey C. Denny with the UF/IFAS Department of Soil and Water Science, Center for Landscape Conservation and Ecology, Gulf Coast Research and Education Center (REC)—Balm have more detailed information in their publication on Identifying Nutrient Deficiencies in Ornamental Plants.