There are three major signs that your plants are in trouble, especially if they are in a limited or enclosed environment, like a hydroponics system: they’re not growing to their full size or height, there is discoloration and there is some form of malformation in the physical structure of the plant.
However, in order to truly understand how individual micronutrient deficiencies can lead to plant malaise, let’s break down the symptoms per nutrient.
Calcium is required for the normal proliferation of cell walls in a plant. Cell walls are important because they keep water in and out at the same time. The key is in the selective porosity of cellular walls. When a plant has calcium deficiency, you will see a die-off of young shoots. There will also be a characteristic crinkling of stems and leaves, plus a general stunted look, especially in mature plants. Don’t expect plants with calcium deficiency to look tall and proud, as their cell walls aren’t forming properly. High temperatures often cause changes in the nutrient solution that prevent the proper uptake of calcium. Blossom rot is also common.
Sulfur is needed by plants to synthesize proteins, which are necessary for the normal functioning of plant organelles and other cellular structures. Plant protein is also required to keep the physical form of the plant stable. Plants also need sulfur to be able to produce fruits and seeds. Therefore, sulfur inadequacy can lead to fewer fruits, stunted fruit formation, and malformation of seeds in the fruits themselves.
The main symptom that you should watch for is the yellowing of the leaves and the presence of a tinge of purple near the base of the affected leaves. Sometimes, yellowing leaves is normal (as long as the manifestation is not generalized) but if you see plenty of leaves that are yellowing with the suspect purple tinge, sulfuric insufficiency may be the culprit. On the other hand, plants can also suffer from toxic levels of sulfur. The known symptom of sulfur toxicity is the inexplicable stunting of leaves.
Iron is used by plants for energy exchange and processing of sugars through plant respiration (yes, plants breathe and interact with the air). All living things require energy and as a plant grows, it not only stores nutrients for human consumption but it also utilizes energy to be able to perform its normal cellular processes. Iron deficiency can easily be tracked if you pay attention to new blossoms. New blossoms will begin to drop off at an alarming rate.
Prior to the die-off, there will also be generalized paling in the plant. If you observe these two symptoms in a sequence, then it’s possible that you’re dealing with iron deficiency. Another symptom is yellowing along the veins of the leaves. So it’s important to look at the leaves themselves to see if the yellow tinge is forming along the veins. Fortunately, since iron is consumed all the time by plants, Fe toxicity is quite rare and almost never happens.
Magnesium is used by plants to manufacture enzymes (catalysts that allow cellular processes to take place) and is also used by plants to manufacture chlorophyll, the green pigment that allows plant leaves to interact and utilize visible wavelengths of light. When there is a magnesium deficiency old leaves begin to curl up and wither while suffering from yellowing/discoloration around the vein areas. Magnesium deficiency’s hallmark sign is the withering of bigger and older leaves and the survival of smaller, newer leaves. The reason for this is that magnesium is transported by plants to newer leaves, leaving the older leaves with insufficient levels of the nutrient.
Boron is calcium’s partner. These two micronutrients are both vital for the formation of normal and sturdy cellular walls. Again, cellular walls don’t just protect cells from each other and the adjoining space in plant tissue. Cellular wall formation directly affects the physical sturdiness and appearance of plants. Boron deficiency can be quite stressful to growers because they will begin to notice major symptoms like brittle stems and poor growth. A plant can’t grow if it cannot manufacture sturdy cellular walls. And the problem is at the cellular level, so any resulting tissue formation will be problematic because tissues are comprised of cells.
There are also instances of too much boron in the nutrient solution. In case of boron toxicity, you will notice characteristic yellowing of the tips of leaves, followed by a mass fall-off of leaves. The sequence of symptoms is important to understand what’s actually happening to your plants. Each type of nutrient deficiency has its own sequence of events, pointing at the possible culprit or problem.
Like magnesium, zinc is used by the plant to create chlorophyll, metabolize energy and generally, keep things going for the plant. Since zinc affects the quality of plant respiration as it draws carbon and oxygen from the atmosphere to create sugars and energy, you can expect physical deformities to manifest almost immediately. The most common sign of zinc deficiency is the crinkling of leaves. The crinkling may occur at the tips of leaves, or at the opposite borders. After crinkling, the leaves will begin to drop off. Note that since this is a deficiency, not all leaves will manifest the same symptom; however, this does not mean that the deficiency is not there to begin with.
Molybdenum is responsible for nitrogen fixing and utilization in plants. Nitrogen also makes it possible for plants to uptake nutrients and create energy. A molybdenum deficiency will deform plants and the leaves will be stunted and have a tinge of yellow about them. Yellow leaves are not good as they will not be able to perform respiration well, leading to the further stunting of the plant. In tomato plants, molybdenum deficiency may lead to all-yellow leaves, which is rare, but still possible.
Heather Fitzpatrick is someone who enjoys gardening & also teaching others about it. She runs OriginHydroponics.com, a site focused on teaching others how to garden without using soil.