Plant Deficiencies
| Nutrient deficiencies tend to affect high light and high CO2
tanks more as the plants use up available nutrients quicker. It is
very hard to measure a lot of the nutrients which is why the
Estimative Index method of dosing works so well by providing
all of them to a small excess. Even so there are times when
something is not quite right with some or all of the plants.
Trying to identify which nutrient is lacking can be a
difficult process at times as one deficiency can mask a
different one. The first thing to look for is whether the
deficiency is affecting new leaves or old leaves. Plant
nutrients are considered to be mobile or immobile. Mobile
nutrients can be reclaimed from old leaves and used to produce
new growth, so problems will show mainly in old leaves.
Immobile nutrients cannot be moved from the older leaves and
so new growth is then affected.
The following table provides a good starting point to identifying plant deficiencies but be aware that with high light not everything is quite so straight forward. For example limiting nitrogen or phosphorus is supposed to effect old leaves, but I have found the opposite to be true in that new growth can sometimes be stunted. This is possibly due to the faster uptake of nutrients under high light. |
| Element | Leaves | Symptom |
| Boron | New | Dead shoot tips and side shoots Delicate stems Similar to calcium deficiency |
| Calcium | New | Distorted leaf growth Twisted and short roots Yellow leaf edges |
| Carbon Dioxide | New | Slow growth Distorted leaf growth Possibly calcium deposits on leaves |
| Copper | New | Dead leaf tips |
| Iron | New | Pale growth of new leaves Leaves can become brittle Yellowing of leaves |
| Magnesium | Old | Yellow patches with veins remaining green Similar to iron as it prevents plant from absorbing iron Distorted leaf growth |
| Manganese | New | Dead yellowish tissue between leaf nerves |
| Molybdenum | Old | Yellow spots between leaf nerves Brown edges Inhibited flowering |
| Nitrogen | Old | Stunted growth Leaves turn yellow and die off Slight reddening of leaves on occasions |
| Phosphorus | Old | Stunted growth Darker leaves Poor root growth |
| Potassium | Old | Pinholes appear which slowly enlarge Yellow patches Curling leaves Stunted growth |
| Sulphur | New | Leaves turn yellow and die off |
| Zinc | Old | Yellowish areas between nerves starting at the edges |
| I haven't included light in the table as it is not really a nutrient in the true sense of the word. It does however play an important part in plant growth. Poor light will create spindly plants with small leaves. Leaves often fall off towards the bottom leaving it bare. |
This page was last updated 13th September 2007