REFERENCE SUFFICIENCY RANGES
ORNAMENTALS & FLOWERS

Poinsettia

C. R. Campbell

• Critical Values
  
  

  Levels at which deficiency symptoms are evident and growth and development are affected.
  N	P	K	Ca	Mg	S	Fe	Mn	Cu	B	Mo
  3.50%	0.15%	1.00%	0.50%	0.20%	0.05%	30 ppm	15 ppm	1 ppm	15 ppm	0.5 ppm

• Sampling Procedures

  The most recent fully expanded or mature leaf is the best indicator of nutritional status. This is the first fully expanded leaf below the growing point.

  Sampling is initiated as soon as plants are large enough that leaf removal will not limit further development.

  Sampling is discontinued when bracts near full development.

  Depending on size, approximately 10–15 leaves are required per sample.

• Sufficiency Ranges
  
  
  • All Growth Stages
    
    

    Macronutrients
    N	P	K	Ca	Mg	S
    4.0–6.0%	0.3–0.6%	1.5–3.5 %	1.00–1.75%	0.3–1.0%	0.1–0.3%

    
    

    Micronutrients
    Fe	Mn	Zn	Cu	B	Mo
    50–300 ppm	25–250 ppm	20–60 ppm	2–10 ppm	25–75 ppm	1–5 ppm

    
    

    Important Ratios

    The N:S ratio should not exceed 18.

    
    

    Excessive or Toxic Nutrient Levels
    N	P	K	Cl	F	Li	Mn	B
    7.3%	0.9%	4.0%	3.0%	5 ppm	20 ppm	1000 ppm	200 ppm
    Boron toxicity is common where irrigation water contains 0.5 ppm B or higher. Excess boron causes a marginal leaf burn that begins on older leaves. Toxicity symptoms progress up the plant with time. Leaf margins contain very high concentrations of boron.
    Lithium toxicity is associated with some water supplies and vermiculite deposits containing high concentrations of this element. Symptoms include marginal burn on older leaves. Leaf margins contain very high concentrations of lithium.

• DRIS Norms

  DRIS norms for poinsettia have not been reported.

• Remarks

  Critical values were taken from the work of Ecke and others (1990) and modified based on experience. Sufficiency ranges and toxicity values were taken from work of Ecke and others (1990) and modified based on experience.

• References

  Ecke P Jr, Matkin OA, Hartley DE. 1990. The poinsettia manual. Encinitas (CA): Paul Ecke Poinsettias. p 121.

Electronic Document Prepared by:
Catherine Stokes, Communication Specialist
Agronomic Division of the N.C. Department of Agriculture and Consumer Services. July 2000.