Foliar fertilization for cannabis: nutrient uptake via leaves

Introduction

Foliar fertilization, also known as foliar feeding, is a method in which nutrients are absorbed directly through the leaves of the cannabis plant. This technique enables the plant to be supplied quickly and efficiently, especially in the event of acute nutrient deficiencies or if root uptake is impaired.

Advantages of foliar fertilization

• Rapid nutrient uptake: Nutrients applied via the leaves can be utilized by the plant within a few hours, which is particularly beneficial in the case of acute deficiencies.

• Bypassing root problems: In the event of problems in the root system or substrate, such as pH fluctuations or root diseases, foliar fertilization offers an alternative nutrient supply.

• Targeted application: Certain micronutrients such as iron, zinc or manganese can be supplied specifically and efficiently via the leaves.

Suitable nutrients for foliar fertilization

Not all nutrients are equally suitable for foliar application. They are particularly effective:

• Micronutrients: Iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), boron (B) and molybdenum (Mo) can be efficiently absorbed via the leaves.

• Macronutrients: Nitrogen (N), phosphorus (P) and potassium (K) can also be supplied in smaller quantities via the leaves, but the absorption efficiency here is lower than for micronutrients.

Optimal application times

• Time of day: The best time for foliar fertilization is early in the morning or late in the evening. At these times, the stomata of the leaves are open, which favors the absorption of nutrients. The risk of burns from sunlight is also reduced.

• Growth phase: Foliar fertilization is particularly useful in the vegetative phase and in the early flowering phase. It should be avoided in the late flowering phase so as not to wet the flowers and thus prevent mold growth.

Application of foliar fertilization

1st Prepare the solution: Mix the selected fertilizer with water according to the manufacturer's instructions. A weaker concentration is often recommended for foliar fertilization, typically 25-50% of the normal dose.

2 Adjust pH: Make sure the solution has a pH between 6.0 and 7.0 to ensure optimal uptake of nutrients.

1. spray technique: Use a fine mist spray to evenly wet the leaves. Make sure to spray both the upper and lower sides of the leaves, as the stomata are mainly on the underside.

4 Ensure air circulation: After application, ensure good ventilation to allow the leaves to dry quickly and minimize the risk of fungal attack.

Important notes

• Avoid overdosing: Too high a concentration of nutrient solution can cause leaf burn. Start with a lower concentration and increase it gradually if necessary.

• Do not spray in direct sunlight: This can burn the leaves. Therefore, choose the early morning or late evening hours for application.

• Regular application: For acute deficiencies, foliar fertilization can be repeated every 3-4 days until improvement occurs. The frequency should then be reduced.

• Combination with root fertilization: Foliar fertilization does not replace regular fertilization via the substrate, but serves as a supplementary measure.

Conclusion

Foliar fertilization is an effective method for quickly supplying cannabis plants with essential nutrients, especially in the case of acute deficiencies or root problems. With the right choice of nutrients, the optimal time of application and correct implementation, this technique can significantly improve the health and productivity of plants.

Pro Tips

• Always use clean, lukewarm water to prepare the spray solution.
• Test the solution on a small leaf area before spraying the entire plant.
• Avoid foliar fertilization in high humidity to prevent mould growth.
• Use special foliar fertilizers that are formulated for Foliar application.
• Make sure that the spray bottle is clean to avoid contamination.