The Role of Each Element
Nitrogen (N) — chlorophyll, amino acids, proteins. Excess: lush foliage, weak roots, increased disease susceptibility. Peak consumption occurs during vegetative growth.
Phosphorus (P) — energy transfer, root development, and generative organ formation. Deficiency: purple tint on lower leaves. Excess: blocks Zn, Fe, and Mn uptake.
Potassium (K) — water balance regulation, stomatal function, sugar synthesis. Deficiency: yellowing of leaf edges. Excess: displaces Ca and Mg through ionic antagonism.
Nutritional Needs by Growth Stage
| Stage | Emphasis |
|---|---|
| Vegetative | Higher N for leaf development |
| Transition to flowering | Lower N, higher P and K |
| Leafy crops (lettuce, greens, microgreens) | N emphasis throughout the entire cycle |
Common Mistakes
- Treating the NPK ratio on a fertiliser package as a guarantee of what the plant will actually absorb
- Adding nitrogen for slow growth without first checking DO, pH, osmotic stress, and micronutrient levels
- Using the same recipe throughout the entire cycle for fruiting crops
Signs of Correct Balance
- Development matches the current growth stage
- Even leaf colour with no chlorosis
- Normal growth without excessive stretching