Calcium is an essential plant nutrient, it is necessary for cell formation, it forms calcium pectate which helps bind cells to one another and strengthens the cell walls of plants. By maintaining cellular integrity it also helps guard against invasive fungal and bacterial diseases. It also helps protect plants against heat stress and is a catalyst that brings proteins that protect against heat shock into play. By strengthening the cell walls it also has a major impact on the quality of fruit produced by the plant
Calcium is necessary for the regulation of the stomata. The stomata or stoma are on the outermost cells of all subterranean plant parts. They allow for the uptake of carbon dioxide, and allows wastes gases to be expelled or exhaled. Without the stomata the plant can't breathe, without calcium and other key nutrients the stomata will not function.
Symptoms of Calcium Buildup or Deficiency
Calcium Deficiency Symptoms
Calcium is transported at a snails pace through the plant and tends to concentrate in older growth and roots before being shared with new growth. As the new growth is the last to receive its dose of calcium it is the first to show symptoms of a deficiency.
Leaf tip burn, browing and dieing back of new growth, distorted leaf margins, Browning of plant tissue - particularly new growth, necrotic patches on young leaves.
In the early blooming phase, abortion of flower and buds is common. Moderate calcium deficiencies may cause twisted and bent leaves, as well as white streaks and leaf margins in new foliage.
Blossom End Rot of many fruiting plants such as tomatoes , peppers, cucumber are symptoms in more mature plants.
Calcium Build up Symptoms
Deficiencies are not the only issue with calcium. Excessive calcium or calcium buildup can also be a problem. If excessive calcium is present in the plants early stages its growth becomes stunted.
In subsequent stages excessive calcium can interfere with the uptake of other nutrients such as magnesium and phosphorous. which will cause deficiency symptoms relative to those nutrients and totally screws up your diagnosis.
Boron deficiencies, although less common resemble calcium deficiencies. Boron deficiencies are rare except when a plant is in an overly dry environment. Which makes it even rarer in hydroponics. Boron is not absorbed well if moisture is lacking, however if the humidity is below 20% relative airborne humidity, a humidifier may be needed.
Causes of Calcium Deficiencies and Buildups
A deficiency of calcium does not necessarily mean you provided insufficient calcium for the plant. Quite frequently it is a calcium intake issue, the calcium is present, but it is just not being transported to where it is needed. You can put all the gas you want in your car - if it doesn't burn, your car still isn't gonna run. If it burns incorrectly your car is not going to run very efficiently or worse case scenario - your car itself is gonna burn.
Calcium transport problems are most commonly caused by environmental stress. Excessive high humidity, which is common in some hydroponic scenarios restricts transpiration and calcium distribution. Inadequate ventilation also restricts transpiration and enhances humidity - so basically poor ventilation and or excess humidity are common causes of Calcium deficiencies even though the nutrient solution may have sufficient calcium present.
Excessive potassium and/or magnesium will also interfere with calcium uptake.
Calcium deficiency is also more apt to occur under an acidic pH. In Hydronics, calcium is absorbed best by the roots in the pH range of 6.2 - 6.5 . Even though the suggested range for the grow media and plants you are growing may vary it is advisable to adjust your pH to suit the situation - in this case a Calcium deficiency.
Excessive calcium or calcium buildup can be caused by a number of issues. One factor to consider is the water you used. If you used 'Hard water' - it already contains deposits of chalk and limestone which have a high percentage of calcium in it. You then add more calcium via your nutrient solution and you now have an excess. Assuming it is being taken up by the plant as nature designed you end up with a excess of calcium which leads to a calcium buildup. See: Hydroponic Water Quality
If using tap water, your water company should be able to tell the approximate calcium content. Calcium content above 70 ppm is hard water. If you notice a white residue on your plumbing / faucets that accumulates over time - chances are you have hard water.
'Soft water' has a much lower mineral content. Water can be 'softened' to a certain degree but it's questionable as to whether its worth the effort. In addition - softening your water can at times lead to more problems than it solves. For instance - water that has gone through a water softener is frequently way too salty for most hydroponic plants.
Reverse osmosis (RO) water will help control Calcium buildup However - Calcium deficiencies are more common with RO water.
Distilled water is actually best - it has a suitable pH and is basically soft. Distilled water is also readily available and cost effective.
Companies that market nutrient solutions will sometimes have a line designed for use with hard water - Hard Water Nutrient Solutions.
Treatment of Calcium Issues in Hydroponic Systems
Calcium Deficiency Treatment
If you are certain, or at least you think you're certain, that you have a calcium deficiency, flush your system with soft or distilled waterto remove any salts and minerals that may have hampered calcium uptake. Restore pH to the proper levels.
Add a suitable Nutrient formula for the crop being grown. As Calcium and Magnesium deficiencies commonly occur simultaneously it is advisable to supplement your solution with calcium and magnesium [Cal-Mag]
Calcium Nitrate will also correct a calcium deficiency assuming it is not caused by an uptake issue. Spraying the fruit of fruit bearing plants is one method. Foliar spray has no discernible effect. Adding Calcium Nitrate to the solution is workable keep in mind that calcium nitrate also contains nitrogen and will increase nirogen levels as well.
In most cases, so long as the plants are not too far gone you should expect to see an improvement fairly quickly. The time frame will vary dependent on the plant - but generally within a week. Older leaves will not recover, but new growth should appear healthy and vibrant.
If you only had a very minor calcium buildup you could simply use the same procedure for a deficiency. Unfortunately in most cases when a calcium buildup has been detected and had an adverse effect on plants it is not 'minor'.
Treating a calcium buildup is a little more involved than treating a deficiency. You could simply indulge your herbicidal tendencies, rip out all your plants and start over again. Or you could perform an "acid-flush" .
1. Evacuate the Plants to a safe temporary locale.
2. Add distilled or RO water and a small amount hydrochloric acid to the reservoir. 3/4 tsp per Gallon.
Note: Hydrochloric acid is volatile and corrosive - it should not be allowed to come into contact with any metallic components of the system. It should also be stored safely as per manufacturers instructions.
Treatment of Calcium Buildup
3. Soak the system for at least a full day but no more than 3 days.
Run the pump for about 6 hours a day durring this time. If you are using a run to waste system run the pump for short periods, a minute or two at a time, each hour and collect the discharge to recirculate.
4. Flush the entire system several times with clean fresh water to remove any acidic residue. It is advisable that any narrow tubing, sprayers or drippers be dismantled and individually washed out.
The pH when you arrive at the final flsuh shoud be above 5.0 - this indicates that the acid has been successfully flushed out. Return the plants and adjust pH and nutrient levels.