Article Index
Foliar Nutrition
Reasons for deficiency
Plant Nutrients
Requirements & signs of deficiencies
Symptoms of nutrient deficiencies
Trace element deficiency table
Influence of the least nutrient
The influence of pH
The effect of pH
Absorbition of nutrients IONS
All Pages

The influence of pH

Put simply, pH is a measure of the acidity or alkalinity on a scale of 1 to 14. A reading of 7 is deemed to be neutral, alkaline if above and acidic if below. The following diagram gives an idea of pH values for a range of commonly found liquids.

pH values for commonly used liquids.
battery acid <1
vinegar <3 acidic
orange juice >4
boric acid 5
milk <7
pure water 7 neutral
blood >7
sea water 8
borax >9
ammonia >11 alkaline
bleach >12
lye <14

The pH value of soil, as a general rule, ranges from about 4,0 to about 8,5. An azalea, for instance, enjoys a pH of between 4,5 and 5,5 . At pH 4,5 or less, there is damage to root membranes and less favourable conditions for growth of beneficial bacteria.

Optimum pH values for some other plants:

  • Camelias 5,5 to 6,5
  • Gardenias 6,0
  • Magnolias 6,5 to 7,0
  • Hydrangeas 4,5 to 6,0 ( the lower value gives a blue colour, the higher value gives a pink colour.)