emporium hydroponucs

Blog Post

Magnesium Deficiency

Brockney C • Mar 05, 2019

Cloudy Yellow or Rusty Spots

Magnesium deficiency in a plant can be noticed by small rusty or yellow spots and when leaves begin to curl up

Plants require magnesium because it is one of the building blocks of chlorophyll. Chlorophyll is what gives the green colour in the leaves and helps a plant to photosynthesise by absorbing the sunlight.

When a plant does not have a sufficient supply of magnesium from its nutrients the oldest leaves begin to exhibit the deficiency. Small spots appear that are either a cloudy yellow or emulate the colour of rust. The leaves gradually become more yellow and begin to curl up. This typically occurs on the older leaves to begin with and then gradually spreads to the younger sections of the plant.

How to spot a deficiency of magnesium

  • Yellow spots on the older leaves
  • Curling of the leaf tips
  • Chlorosis between the veins
  • Reduced production
  • Purple stems

Potential causes

  • Soil that has a low pH
  • An excessively cold or wet environment for the roots
  • A poor and undeveloped system of roots
  • An excessively high EC value in the rooting substrate
  • Too much potassium, calcium and ammonia (nitrogen) because this can react and form new magnesium compounds that the plant can't feed from

Prevention

  • Magne-Cal+ from Plant Magic is a good nutrient that contains magnesium oxide (MgO), calcium oxide (CaO) and iron (Fe).
  • Keep the pH level between 6.0 and 7.0
  • Keep the temperature of the growing medium and nutrient solution between 21 and 23 degrees celcius
This will ensure that sufficient magnesium is available and the plant will be able to efficiently absorb it.

Cure

Flushing the system with clean water then replenishing the feed is a good idea.

Feed with Magne-Cal+ or a similar, good quality magnesium nutrient.

1ml of Magne-Cal is added to 1 litre of water and this will replenish the supply to the plant.

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