Fe deficiency in Calibrachoa

Fe deficiency in Calibrachoa

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Scientific Name
Iron (Fe)
Atomic Number
26
Atomic Weight u
55.845
Elemental Group
Micro elements (B, Cl, Cu, Fe, Mn, Mo, Ni, Zn) | Micronutrients
Available Forms

Available forms of Iron (Fe) for use in Pot and Bedding Plants

  • Ferrous sulfate (FeSO₄·7H₂O, “Iron sulfate”) – soluble, fast-acting; foliar or drench.
  • Ferric sulfate (Fe₂(SO₄)₃, “Iron(III) sulfate”) – soluble, acidifying; media drenches in some programs.
  • Iron chelate (Fe-EDDHA, “EDDHA-Fe”) – highly stable, effective in high-pH media.
  • Iron chelate (Fe-DTPA, “DTPA-Fe”) – effective to about pH 7; common in fertigation.
  • Iron chelate (Fe-EDTA, “EDTA-Fe”) – economical; use only in acidic substrates (pH ≤6).
  • Iron citrate (C₆H₅FeO₇, “Ferric citrate”) – soluble organic form for foliar/specialty use.
  • Iron lignosulfonate (varied composition, “Iron lignosulfonate”) – organic complex; soil/media application.
  • Iron frits (varied composition, “Slow-release Fe frits”) – glass-fused carriers for controlled release.

Iron (Fe) Deficiency in Calibrachoa – Pot and Bedding Plants

Symptoms

  • Interveinal chlorosis on the youngest leaves; veins remain green while the lamina turns yellow to nearly white.
  • Reduced shoot growth and smaller, weak leaves.
  • In advanced cases, leaf margins and tips may necrotize; overall plant vigor declines.
  • Poor bud set and diminished flowering quality.

Causes

  • High substrate pH reducing Fe solubility (pH drift from liming or alkaline irrigation).
  • Irrigation water high in bicarbonates raising media pH over time.
  • Excess phosphorus or competing metals (Mn, Zn, Cu) antagonizing Fe uptake.
  • Poor root function due to waterlogging, compaction, or root disease.

Correction

  • Apply iron chelates as foliar sprays for rapid greening (choose EDDHA for high pH, DTPA for pH ≤7, EDTA for acidic media).
  • Drench with chelated Fe to restore root-zone supply; avoid excessive rates to prevent staining or toxicity.
  • Lower substrate pH toward 5.5–6.0 (or 5.0–5.5 for sensitive species) and acidify irrigation water if alkalinity is high.
  • Prefer ammonium-based N sources to promote localized root-zone acidification.

Prevention

  • Maintain substrate pH 5.5–6.0 and monitor drift with regular media testing.
  • Manage irrigation water alkalinity with acid injection when needed.
  • Include chelated Fe in ongoing fertigation for sensitive species.
  • Balance P and micronutrient programs; avoid excessive Mn, Zn or Cu.
  • Use well-aerated mixes and avoid overwatering to keep roots active.

Fe deficiency in Calibrachoa

Scientific Name
Iron (Fe)
Atomic Number
26
Atomic Weight u
55.845
Elemental Group
Micro elements (B, Cl, Cu, Fe, Mn, Mo, Ni, Zn) | Micronutrients
Available Forms

Available forms of Iron (Fe) for use in Pot and Bedding Plants

  • Ferrous sulfate (FeSO₄·7H₂O, “Iron sulfate”) – soluble, fast-acting; foliar or drench.
  • Ferric sulfate (Fe₂(SO₄)₃, “Iron(III) sulfate”) – soluble, acidifying; media drenches in some programs.
  • Iron chelate (Fe-EDDHA, “EDDHA-Fe”) – highly stable, effective in high-pH media.
  • Iron chelate (Fe-DTPA, “DTPA-Fe”) – effective to about pH 7; common in fertigation.
  • Iron chelate (Fe-EDTA, “EDTA-Fe”) – economical; use only in acidic substrates (pH ≤6).
  • Iron citrate (C₆H₅FeO₇, “Ferric citrate”) – soluble organic form for foliar/specialty use.
  • Iron lignosulfonate (varied composition, “Iron lignosulfonate”) – organic complex; soil/media application.
  • Iron frits (varied composition, “Slow-release Fe frits”) – glass-fused carriers for controlled release.
Fe deficiency in Calibrachoa

Iron (Fe) Deficiency in Calibrachoa – Pot and Bedding Plants

Symptoms

  • Interveinal chlorosis on the youngest leaves; veins remain green while the lamina turns yellow to nearly white.
  • Reduced shoot growth and smaller, weak leaves.
  • In advanced cases, leaf margins and tips may necrotize; overall plant vigor declines.
  • Poor bud set and diminished flowering quality.

Causes

  • High substrate pH reducing Fe solubility (pH drift from liming or alkaline irrigation).
  • Irrigation water high in bicarbonates raising media pH over time.
  • Excess phosphorus or competing metals (Mn, Zn, Cu) antagonizing Fe uptake.
  • Poor root function due to waterlogging, compaction, or root disease.

Correction

  • Apply iron chelates as foliar sprays for rapid greening (choose EDDHA for high pH, DTPA for pH ≤7, EDTA for acidic media).
  • Drench with chelated Fe to restore root-zone supply; avoid excessive rates to prevent staining or toxicity.
  • Lower substrate pH toward 5.5–6.0 (or 5.0–5.5 for sensitive species) and acidify irrigation water if alkalinity is high.
  • Prefer ammonium-based N sources to promote localized root-zone acidification.

Prevention

  • Maintain substrate pH 5.5–6.0 and monitor drift with regular media testing.
  • Manage irrigation water alkalinity with acid injection when needed.
  • Include chelated Fe in ongoing fertigation for sensitive species.
  • Balance P and micronutrient programs; avoid excessive Mn, Zn or Cu.
  • Use well-aerated mixes and avoid overwatering to keep roots active.