Calcium (Ca) Deficiency

Scientific Name

Calcium (Ca)

Atomic Number

Atomic Weight u

40.078

Elemental Group

Meso elements (Ca, Mg, S ) | Secondary macronutrients

Available Forms

Available forms of Calcium (Ca) for Horticultural Production

Calcium nitrate (Ca(NO₃)₂, “Calcium nitrate”) – highly soluble; primary Ca source in fertigation.
Calcium chloride (CaCl₂, “Calcium chloride”) – very soluble; rapid foliar correction (use with caution to avoid leaf burn).
Calcium sulfate (CaSO₄·2H₂O, “Gypsum”) – sparingly soluble; supplies Ca without strongly raising pH.
Calcium carbonate (CaCO₃, “Calcitic lime”) – slow to moderate release; raises pH while supplying Ca.
Dolomitic lime (CaMg(CO₃)₂, “Dolomite”) – dual supply of Ca and Mg; also used for pH adjustment.
Calcium hydroxide (Ca(OH)₂, “Hydrated lime”) – fast-acting pH amendment and Ca source.
Calcium chelate (Ca-EDTA, “EDTA-Ca”) – soluble form for foliar or specialty applications.
Calcium acetate (Ca(C₂H₃O₂)₂, “Calcium acetate”) – soluble; used in liquid fertilizer formulations.

Container Nursery Stock, Pot & Bedding Plants

Appears first on youngest tissues since Ca is immobile within the plant.
Deformed, strap-like, cupped, or twisted young leaves; tip burn and marginal necrosis are common.
Weak peduncles, bud or blossom abortion, and poor flower quality.
Poor root growth with stubby, brittle root tips.
Overall plant vigor reduced due to impaired structural integrity.

Insufficient Ca in fertilizers or irrigation water.
Interrupted Ca transport caused by irregular moisture, low transpiration (dense canopy, poor airflow), or water stress.
Antagonism from excessive NH₄⁺, K⁺, or Mg²⁺ competing with Ca²⁺ uptake.
High electrical conductivity (EC) in the root zone restricting Ca mobility.

Fertilizer supply: Provide Ca via calcium nitrate in fertigation; supplement with gypsum for sustained release without raising EC excessively.
Foliar application: Use calcium chloride sprays for rapid correction on developing tissues (apply in cool periods to avoid leaf burn).
Irrigation management: Maintain consistent substrate moisture to support continuous Ca transport.
Reduce antagonists: Minimize excess NH₄⁺, K⁺, and Mg²⁺ that interfere with Ca uptake.
Keep EC within the target range to avoid stress-induced restriction of Ca movement.

Ensure a continuous Ca supply through fertigation (e.g., calcium nitrate) or gypsum in substrate mixes.
Promote transpiration by managing canopy density, air circulation, and climate conditions.
Irrigate consistently to avoid dry-down cycles that disrupt Ca delivery.
Avoid excessive NH₄⁺, K⁺, or Mg²⁺ that compete with Ca uptake.
Routinely monitor substrate EC and Ca levels with testing programs.