The vegetative growth phase is one of the most important stages in cannabis cultivation. During this time, the plant lays the foundation for strong flowers and high yields. Whether you’re a beginner or an experienced grower, optimizing this phase can make the difference between a mediocre harvest and a top-notch one!
In this guide you will learn:
- What vegetative growth is and why it is so important
- The best environmental conditions for strong growth
- Essential nutrients and irrigation techniques
- Training methods for maximum yields
- How to master the transition to the flowering phase
Let’s get started!
What is vegetative growth in cannabis?
During the vegetative phase, the cannabis plant focuses on developing strong roots, stems, and leaves—the foundation for later, thick buds. This phase follows germination and precedes flowering.
Key features:
- Rapid growth of stems and leaves
- High nutrient requirements (especially nitrogen)
- Development of a strong root system
- Preparing for the flowering phase
If you manage this phase well, you will get healthier plants, higher yields and greater resistance to pests and diseases.
Optimal conditions for vegetative growth
For your cannabis plants to grow optimally, you need to create the right conditions.
1. Lighting requirements
- Light cycle: 18 hours light / 6 hours dark (18/6) is ideal. Some growers use 24/0 for faster growth.
- Light spectrum: Blue light (400-500 nm) promotes compact, bushy growth.
- Light intensity: Strong, even lighting prevents long, asparagus-like growth.
2. Nutrients
- Nitrogen (N) is particularly important now – it ensures strong leaves and stems.
- Phosphorus (P) and potassium (K) support root formation and cell strength.
- Trace elements such as calcium, magnesium and iron must not be missing.
Tip: Use a high-quality growth fertilizer and follow the dosage recommendations to avoid over-fertilization.
3. Irrigation
- Water when the top layer of soil (about 2 cm) is dry.
- Avoid waterlogging – it leads to root rot.
- Use pH-adjusted water (optimal: 6.0–6.5 for soil, 5.5–6.0 for hydroponics).
4. Temperature & Humidity
- Temperature: Ideal is 22–28°C (during the day), not below 18°C at night.
- Humidity: 40–70% – young plants prefer a little more humid (~60–70%), older plants prefer a little more dry (~40–50%).
Training techniques for better yields
During the vegetative phase, you can train your plants to bring more light and air to all bud sites.
1. Low-Stress-Training (LST)
- Carefully bend and secure branches to achieve a flatter, wider shape.
- Advantages: More light for all shoots → more buds!
2. Topping
- Cut off the tip of the main stem to force two main colas.
- Advantages: Bushier growth, more flower buds.
3. Pruning
- Remove weak or shaded leaves and shoots.
- Advantages: The plant puts its energy into the upper, light-rich areas.
The transition to the flowering phase
After 3–6 weeks (depending on the variety and desired size), you can initiate flowering:
- Change the light: To 12/12 (12 hours light, 12 hours darkness).
- Adjust fertilizer: Now the plant needs more phosphorus and potassium.
- Avoid stress: No more repotting or strenuous training!
Tip: Look for the first buds after 1-2 weeks.
Conclusion
The vegetative phase is the foundation for a successful harvest. If you give your plants enough light, the right nutrients, and an optimal environment, they will reward you with vigorous growth and high yields.
Ready for the next stage? Then read our guide to the flowering phase!