Growing great cannabis boils down to controlling these 7 factors:
- Temperature
- Humidity
- Light
- Air flow
- CO2
- Nutrients/water
- Pest prevention
Let’s break them down:
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1. Temperature Control
Cannabis likes it warm, but not too hot:
| Growth Stage | Day Temp | Night Temp |
|---|---|---|
| Seedlings | 75-85°F | 70°F |
| Vegetative | 70-85°F | 65-68°F |
| Flowering | 65-80°F | 55-70°F |
Keep it steady with:
- Temperature controllers
- LED lights (less heat)
- Good air flow
- Regular monitoring
If it gets too hot (85°F+), increase air exchange or adjust lighting. Too cold (below 65°F)? Use heat mats for seedlings and insulate your grow room.
2. Humidity Management
Humidity needs change as plants grow:
| Growth Stage | Ideal Humidity |
|---|---|
| Seedlings | 65-70% |
| Vegetation | 40-70% |
| Early Flower | 40-50% |
| Late Flower | 30-40% |
Control it with:
- Hygrometers
- Dehumidifiers/humidifiers
- Fans
- Smart watering
Too high? You risk mold. Too low? Plants dry out. Stay on top of it.
3. Light Requirements
Cannabis needs different light at each stage:
| Growth Stage | Light Intensity | Light Schedule |
|---|---|---|
| Seedlings | 100-180 µmol/m2/s | 18-24 hrs light |
| Vegetative | 400-800 µmol/m2/s | 18 hrs light/6 dark |
| Flowering | 800-1500 µmol/m2/s | 12 hrs light/12 dark |
LEDs are a solid choice. They’re efficient and run cool. But HID lights work too, especially in cold spots.
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4. Air Flow and Ventilation
Good air flow is crucial. It:
- Strengthens stems
- Controls temp/humidity
- Fights mold and pests
- Provides CO2
Set up:
- Oscillating fans for a gentle breeze
- Exhaust system with fan and ducting
- Carbon filter for odor control
Replace all air every 1-3 minutes. Keep humidity 50-60% (70% for seedlings).
5. CO2 Management
Extra CO2 can boost growth by 20-30%. Aim for:
| Growth Stage | Optimal CO2 (PPM) |
|---|---|
| Seedlings | 1000-1500 |
| Vegetative | 1200-1500 |
| Flowering | 1200-1500 |
Add CO2 with tanks, generators, or bags. Use a monitor to check levels.
6. Nutrients and Water
Get pH right:
- Soil: 6.0 to 7.0
- Hydro: 5.5 to 6.5
Water deeply but less often. Let soil dry between waterings.
Nutrients change as plants grow:
| Growth Stage | NPK Ratio |
|---|---|
| Early veg | 2:1:2 – 4:2:3 |
| Mid-veg | 10:5:7 |
| Late veg | 7:7:7 |
| Early bloom | 5:7:10 |
| Mid-bloom | 6:10:15 |
| Late bloom | 4:7:10 |
Start low, increase slowly. Flush before harvest.
7. Pest and Disease Prevention
Stay clean:
- Remove debris daily
- Clean tools
- Use grow-only clothes
Manage pests:
- Use sticky traps
- Try natural predators
- Apply neem oil in veg stage
- Keep humidity under 50%
Check plants weekly for pests and diseases. Act fast if you spot issues.
Growing cannabis takes skill and attention. But with these factors dialed in, you’re on track for a great harvest.
