Posted on by Jason Gibson

Iron deficiencies and how to spot them

Deficiencies are in a sense, the plants form of communication to us, their ‘true language’ and as we evolve in the garden so does our understanding of the plant language.

Until intuition and understanding takes over, you will most likely be reliant on your local garden store, articles and like-minded people a little further up in skill set.

What causes plant deficiencies?

  • An Insufficient amount a food, low EC
  • pH instability, in turn impacting nutrient availability
  • Too much food causing a lock out of nutrients, high EC
  • Temperature & humidity
  • Environmental factors (HVAC)


Iron deficiencies are most commonly confused with magnesium deficiencies.

Iron deficiencies show in very similar ways to magnesium deficiencies, as the plant will lack the green pigment in between leaf segments, veins remain green, so diagnosis can be quite tough for a new gardener, if in doubt keep reading.

The main difference between the two deficiencies is that Iron shows an even fading between the leaf segments eventually progressing into yellow paneling.

Magnesium also fades the leaf segments however the difference here is if the symptom if observed closely it can be seen as a broken fade, progressively turning into faded blotches/freckles.  

Seedlings will actually present an Iron deficiency as a partial fading of leaves, starting from the leaflet array closest to the petiole.

Quick facts:

  1. Nitrogen is reliant on iron as its role in Nitrogen fixation.
  2. Iron is a mobile micronutrient.

The most abundant form of Iron in soils is ferric oxide (Fe2O3) or hematite, which is an extremely insoluble form of iron and imparts a reddish colour to the soil.