
Identify Symptoms of Nitrogen Deficiency in Plant Leaves
A nitrogen deficiency can be recognised by yellow leaves. This is because chlorophyll disappears from the leaves. You'll first see this happen in the older leaves at the bottom of the plant. This happens because plants transport the available nitrogen to their young leaves and growing points. Eventually the growth of plants will stop as a result, and leaves will fall off. Some plants may see the leaves turn purple instead of yellow. Among others, this happens in multiple varieties of cabbage. A plant with a nitrogen deficiency will remain smaller than a healthy plant. The same goes for its fruits. Plants with a nitrogen deficiency are also more susceptible to problems like diseases and insects.
How do you recognise a nitrogen deficiency?
- First, the older leaves turn yellow-green. This colouring will spread from the inside of the leaves to the outside.
- Next, the yellowing will spread to the base of the leaf and the veins.
- Eventually, the growth of the plants stops and the leaves fall off.
- The stems of your plants will turn purple or reddish.

What is the (possible) cause?
- Too much potassium, zinc and manganese in the soil or substrate.
- Too much chloride in the soil.
- Too little nitrogen available in the soil or substrate.
- The pH value of the root environment is too high.
- The root system of the plant may be dysfunctional. This can be caused by damage, disease or a low soil temperature.
- Nitrogen is easily soluble. This means it can easily be washed out of the soil.