Calcium is a vital nutrient, performing a large number of vital roles in plant biology. Itโs a crucial component in plant cell walls and helps transport other minerals from one side of cell membranes to the other. Itโs also involved in some enzyme functions.
Itโs whatโs known as an immobile nutrient โ once the plant has put it to use in one part of its structure, it canโt be relocated. Thatโs why we see deficiency in young leaves first โ even if old leaves have more than enough, the calcium is fixed and canโt travel to where itโs needed.
Without enough calcium, those membranes become weak. The cell walls canโt control their permeability, resulting in the leeching of vital nutrients and an eventual waterlogging of affected cells. Mostly we see it as yellowing leaves, especially in newer growth, and fruit that becomes soggy and sodden from too much moisture.
Magnesium is just as important. Itโs a key component in the construction of chlorophyll, arguably the most important of all chemicals inside a plant. Chlorophyll is the powerhouse of the plant. Itโs responsible for turning oxygen and water into sugar, fueling all the plant's growth. Without it, thereโs no chance of vigorous growth at all
Unlike calcium, magnesium is mobile and can be redeployed, so to speak, if the plant becomes deficient. As a result, magnesium deficiencies show in older leaves first, as the plant shifts its dwindling supplies to new growth.
Chlorosis is the defining trait of magnesium deficiencies. Leaves turn yellow, from the oldest to the youngest. It makes sense โ after all, no magnesium, no chlorophyll.
Many Calmag solutions include iron, usually as a chelate. This is because many of the conditions that lead to soils poor in calcium and magnesium can also lead to low levels of iron, so it pays to cover all bases. Iron deficiencies also cause the same sort of chlorosis as magnesium deficiencies, so it sometimes pays to apply both at once.
(Chelation is a type of bonding of ions and the molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These ligands are called chelants, chelators, chelating agents, or sequestering agents. They are usually organic compounds, but this is not a necessity.)
Others will include nitrogen, too, presumably because plants need a fairly consistent supply of the stuff, and a deficient plant is likely to spring to life, hungry and ready to grow, once the deficiency is corrected. This is not the case for all brands, so it pays to check โ there are plenty of cases where a low or nitrogen fertilizer is preferred.
Calcium and magnesium work in concert within the plant, and so for many years it was assumed you had to ensure a good ratio of calcium to magnesium in order to get good growth from your plants.
We now know that itโs both simpler and more complicated than that. The ratio of calcium to magnesium in the soil isnโt important, provided thereโs enough of both for whatever is growing.
However too much calcium can cause a drop in available magnesium. The two get along and readily bind to each other. You may well wind up with a magnesium deficiency if you go too hard with a purely calcium-based amendment. Itโs why Cal-mag fertilizers are so useful โ they prevent magnesium depletion while addressing both deficiencies at once.
Cal-mag is best used regularly. As calcium is non-mobile, it needs to be present in the soil for use all through the growing season.
You can also use Calmag to treat either magnesium deficiencies or calcium deficiencies as they appear. Both show up as chlorosis, with magnesium depleting the green from old leaves and calcium from the young
Coco substrates have a few unique chemical properties that can cause problems if not treated. Chief among these is the high amount of potassium naturally found in coco. This potassium tends to swap places with calcium in nutrient solutions, resulting in too much potassium and not enough calcium in your system. Fortunately, treating with Calmag is a good way to remediate this. The magnesium has its own part to play in the complex chemistry happening at the root level, but together they can work to create a supportive growing environment for your plants.
How you apply the Calmag will determine how effective it is, as well as what youโre hoping to achieve.
As a preventative measure, you may never see the Calmag do its work. Thatโs the point โ you are preventing the deficiencies from developing. If applied judiciously, itโs an invisible barrier, protecting you from crop failure and poor growth.
But if used to treat a diagnosed deficiency, the impact will be felt fastest with foliar application. Magnesium deficiencies will correct quite quickly. While already damaged leaves wonโt revive, the grim march of yellow will stop almost immediately. Calcium deficiency is slower to spot, as itโs tied to the development of new tissue, but once youโve corrected the problem the next wave of leaves or blossoms should be in good health.
Soil application takes longer for the plant to process, but it tends to be more enduring. It can take a few days for the minerals to work their way through a large plant, but once they do itโs a long-lasting result.
You can always have too much of a good thing, and Cal-Mag is no different.
At best, itโs possible to use Cal-mag to treat disorders caused by totally unrelated deficiencies, or even bacteria or fungus. While in these cases the Cal-mag itself isnโt going to cause too many problems, they certainly arenโt going to fix your problem.
More critically, both calcium and magnesium can spell trouble in too high concentrations. Too much calcium in the soil can result in the uptake of too much of other minerals and not enough of others, a tricky thing to detect. Magnesium sickness is easier to spot, leaving browning on the tips of new growth.