P deficiency in Hydrangea (Pot & Bedding Plants)

P deficiency in Hydrangea (Pot & Bedding Plants)

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Scientific Name
Phosphorus (P)
Atomic Number
15
Atomic Weight u
30.974
Elemental Group
Macro elements (N, P, K ) | Primary macronutrients
Available Forms

Available forms of Phosphorus (P) for use in Pot and Bedding Plants

  • Monoammonium phosphate (MAP, NHâ‚„Hâ‚‚POâ‚„) – soluble, provides both N and P; commonly used in fertigation.
  • Diammonium phosphate (DAP, (NHâ‚„)â‚‚HPOâ‚„) – highly soluble, supplies N and P; used in liquid or granular fertilizers.
  • Monopotassium phosphate (MKP, KHâ‚‚POâ‚„) – soluble, supplies both K and P; ideal for fertigation and foliar sprays.
  • Triple superphosphate (TSP, Ca(Hâ‚‚POâ‚„)₂·Hâ‚‚O) – concentrated P source; slower acting in substrate, suitable for long-term correction.
  • Rock phosphate (apatite, Caâ‚…(POâ‚„)₃(F,Cl,OH)) – natural, slow-release phosphorus; limited solubility, more effective in acidic substrates.
  • Ammonium polyphosphate (APP, mixture of (NHâ‚„)nH(n+1)PnO3n+1) – highly soluble, liquid P fertilizer; can be blended with other nutrients.
  • Phosphoric acid (H₃POâ‚„) – highly soluble, used for rapid correction via fertigation or foliar sprays.
  • Calcium magnesium phosphate (CaMg(POâ‚„)â‚‚) – slow-release form, supplies both Ca and Mg along with P.

Phosphorus (P) Deficiency in Hydrangea – Pot and Bedding Plants

Symptoms

  • Stunted growth: Plants show slower shoot and root development.
  • Leaf coloration: Leaves may turn dark green to purplish, especially on older leaves.
  • Delayed flowering: Flower buds may be fewer, smaller, or delayed in development.
  • Thin stems: Stems may appear weaker or more brittle.
  • Root development: Reduced root growth can occur in substrate-limited systems.

Causes

  • Low P in substrate: Especially in peat, coir, or sandy mixes.
  • High pH: P becomes less available in alkaline conditions (>6.5–7.0).
  • Excessive Ca or Fe: High calcium or iron levels can tie up available phosphorus.
  • Leaching: Frequent irrigation can remove soluble phosphorus from substrate.

Correction

  • Fertigation: Apply water-soluble phosphorus sources such as MAP, DAP, or MKP through irrigation.
  • Substrate amendment: Mix in slow-release or readily available phosphorus sources like triple superphosphate or phosphate rock.
  • pH adjustment: Maintain substrate pH in the slightly acidic range (5.5–6.5) for optimal P uptake.
  • Balanced fertilization: Avoid excessive nitrogen, potassium, or calcium that can interfere with phosphorus absorption.
  • Foliar application: Use phosphoric acid or MKP sprays for rapid correction of deficiency symptoms.

Prevention

  • Fertigation: Apply water-soluble phosphorus sources such as MAP, DAP, or MKP through irrigation.
  • Substrate amendment: Mix in slow-release or readily available phosphorus sources like triple superphosphate or phosphate rock.
  • pH adjustment: Maintain substrate pH in the slightly acidic range (5.5–6.5) for optimal P uptake.
  • Balanced fertilization: Avoid excessive nitrogen, potassium, or calcium that can interfere with phosphorus absorption.
  • Foliar application: Use phosphoric acid or MKP sprays for rapid correction of deficiency symptoms.

P deficiency in Hydrangea (Pot & Bedding Plants)

Phosphorus (P)
Scientific Name
Phosphorus (P)
Atomic Number
15
Atomic Weight u
30.974
Elemental Group
Macro elements (N, P, K ) | Primary macronutrients
Available Forms

Available forms of Phosphorus (P) for use in Pot and Bedding Plants

  • Monoammonium phosphate (MAP, NHâ‚„Hâ‚‚POâ‚„) – soluble, provides both N and P; commonly used in fertigation.
  • Diammonium phosphate (DAP, (NHâ‚„)â‚‚HPOâ‚„) – highly soluble, supplies N and P; used in liquid or granular fertilizers.
  • Monopotassium phosphate (MKP, KHâ‚‚POâ‚„) – soluble, supplies both K and P; ideal for fertigation and foliar sprays.
  • Triple superphosphate (TSP, Ca(Hâ‚‚POâ‚„)₂·Hâ‚‚O) – concentrated P source; slower acting in substrate, suitable for long-term correction.
  • Rock phosphate (apatite, Caâ‚…(POâ‚„)₃(F,Cl,OH)) – natural, slow-release phosphorus; limited solubility, more effective in acidic substrates.
  • Ammonium polyphosphate (APP, mixture of (NHâ‚„)nH(n+1)PnO3n+1) – highly soluble, liquid P fertilizer; can be blended with other nutrients.
  • Phosphoric acid (H₃POâ‚„) – highly soluble, used for rapid correction via fertigation or foliar sprays.
  • Calcium magnesium phosphate (CaMg(POâ‚„)â‚‚) – slow-release form, supplies both Ca and Mg along with P.
P deficiency in Hydrangea (Pot & Bedding Plants)
Image Source: Everris Research (NL), care of ICL

Phosphorus (P) Deficiency in Hydrangea – Pot and Bedding Plants

Symptoms

  • Stunted growth: Plants show slower shoot and root development.
  • Leaf coloration: Leaves may turn dark green to purplish, especially on older leaves.
  • Delayed flowering: Flower buds may be fewer, smaller, or delayed in development.
  • Thin stems: Stems may appear weaker or more brittle.
  • Root development: Reduced root growth can occur in substrate-limited systems.

Causes

  • Low P in substrate: Especially in peat, coir, or sandy mixes.
  • High pH: P becomes less available in alkaline conditions (>6.5–7.0).
  • Excessive Ca or Fe: High calcium or iron levels can tie up available phosphorus.
  • Leaching: Frequent irrigation can remove soluble phosphorus from substrate.

Correction

  • Fertigation: Apply water-soluble phosphorus sources such as MAP, DAP, or MKP through irrigation.
  • Substrate amendment: Mix in slow-release or readily available phosphorus sources like triple superphosphate or phosphate rock.
  • pH adjustment: Maintain substrate pH in the slightly acidic range (5.5–6.5) for optimal P uptake.
  • Balanced fertilization: Avoid excessive nitrogen, potassium, or calcium that can interfere with phosphorus absorption.
  • Foliar application: Use phosphoric acid or MKP sprays for rapid correction of deficiency symptoms.

Prevention

  • Fertigation: Apply water-soluble phosphorus sources such as MAP, DAP, or MKP through irrigation.
  • Substrate amendment: Mix in slow-release or readily available phosphorus sources like triple superphosphate or phosphate rock.
  • pH adjustment: Maintain substrate pH in the slightly acidic range (5.5–6.5) for optimal P uptake.
  • Balanced fertilization: Avoid excessive nitrogen, potassium, or calcium that can interfere with phosphorus absorption.
  • Foliar application: Use phosphoric acid or MKP sprays for rapid correction of deficiency symptoms.