Ornamental plants need a balanced mixture of macro- and micro-nutrients to grow, bloom and fruit properly. Plants that are missing one or more essential nutrients may have discolored and distorted foliage, as well as stunted growth. Ornamental plants that have been weak by the lack of one or more nutrients are more susceptible to insects, diseases and environmental stresses. Recognizing the visual symptoms of nutrient deficiencies is the first step to identifying and correcting the problem. Soil and plant tissue tests can pinpoint the nutrient or nutrients needed, as well as the amounts required to correct the problem. Contact your local county extension office for more information on how to identify deficiency symptoms in ornamental plants, and how to submit soil and plant tissue for testing.
The symptoms of deficiencies of the three primary macro-nutrients first occur on the older leaves of ornamental plants. Lack of nitrogen (N) causes light green to yellow leaves on the whole plant and slow plant growth. Light greenish-yellow, red or wine colored leaves and stunted growth are symptoms of phosphorus (P) deficiency.
The symptoms of insufficient potassium (K) depend on the species of plant affected and the severity of the deficiency. Some indications are yellow or dead tissue between the veins of the leaves, dead tissue along the margins of the leaves or dead spots on the leaves.
Yellowing of leaves on an ornamental shrub is an indication of the lack of one of the secondary macro-nutrients. An insufficiency of calcium (Ca) causes yellow or light green uneven areas on the leaves, blunt stems and short thick roots. Solid yellow leaves indicate the lack of Sulfur (S). The symptoms of magnesium (Mg) deficiency first occur on the older leaves with yellowing between the veins and along the margins, but no dead leaf tissue. Affected plants produce small leaves, grow slowly, and in severe cases, drop their leaves.
The symptoms of micro-nutrient deficiencies appear on the newer leaves of ornamental plants. A lack of Boron (B) causes dark green, brittle leaves that are puckered or cupped on stems with short internodes.
A copper (Cu) deficiency results in yellow tissue between the veins of the leaves. A line of green tissue remains along the veins, along the edges and on the tips of the leaves. The symptoms spread rapidly and the leaves quickly die. Iron deficiency is common in alkaline or poorly drained soil, as well as in plants with nematodes or root rot. The main symptom is yellowing between the veins of the leaves. Affected plants produce small, nearly white leaves in severe cases. Symptoms of Manganese (Mn) deficiency vary among affected species of plants. Most have yellowing of the leaves between the veins. Others may have yellow or dead spots in the leaves. As the conditions worsen, affected plants produce tiny leaves and tip dieback occurs.
A lack of zinc (Zn) causes small leaves, stems with short internodes and yellowing of the leaf tissue between the veins with some green remaining along the veins. Leaves may grow in a rosette–a group of curled leaves.