Proper watering is critical for cannabis health. When, how much and how to water for optimal root growth.
Irrigation is one of the most important and often mismanaged aspects of cannabis cultivation:
Irrigation principles:
Wet-dry cycles:
- Allow substrate to dry between waterings
- Roots need oxygen phases
- Overwatering most common beginner's mistake
- Rhythm develops with plant growth
Drainage is critical:
- 10-20% of the irrigation water should run off
- Waterlogging leads to root rot
- Drainage holes in all pots
- Empty saucer after 1 hour
Water quality:
- Leave tap water to stand for 24 hours (chlorine evaporates)
- adjust pH value to 6.0-6.5
- Know the EC value of the water
- Consider RO system for hard water
Timing strategies:
Finger test:
- feel 2-3cm deep in substrate
- Dry = time to water
- Moist = still waiting
- Experience develops feeling
Pot weight method:
- Weigh dry vs. wet pot
- Learn the difference in weight
- Fastest method for experienced users
- Especially with the same pot sizes
Plant signals:
- Slightly drooping leaves = thirst
- Heavily drooping leaves = overwatering
- Healthy plants show subtle signals
- Never wait until wilting
Watering techniques:
Slow, thorough watering:
- Distribute water slowly and evenly
- Moisten the entire substrate surface
- Pause between watering
- Until 10-20% drainage is reached
Ring watering:
- Distribute water in a ring around the trunk
- Promotes root spread
- Prevents stem rot
- Especially for young plants
Water from below:
- Water in saucer
- Substrate absorbs from below
- Prevents surface compaction
- Good for sensitive seedlings
Watering equipment:
Watering cans:
- Long, thin spout
- Controlled water delivery
- Different sizes depending on setup
- Best control for beginners
Pressurised sprayer:
- Even distribution
- Adjustable jet
- Good for large plants
- Also for foliar spraying
Automatic systems:
- Drip irrigation
- Timer controlled
- Even supply
- Suitable for holidays
Substrate-specific irrigation:
Soil:
- Every 2-4 days depending on size
- Deep and penetrating
- Longer dry phases okay
- Drainage particularly important
Coco:
- Daily or every 2nd day
- Never allow to dry out completely
- Higher frequency, smaller quantities
- Constant light moisture
Hydro:
- Continuously or several times a day
- Roots never dry
- Timer control standard
- Reservoir management important
Calculate water quantities:
Pot size as a basis:
- 10 litre pot = approx. 1-2 litres of water
- 20 litre pot = approx. 2-4 litres of water
- Depending on plant size
- Consider drainage quantity
Growth adaptation:
- Seedlings: a few litres
- Vegetative: 0.5-2L depending on size
- Flowering: 2-5 litres for large plants
- Increase with plant growth
Automated watering:
Drip systems:
- One dripper per pot
- Timer-controlled intervals
- Even distribution
- Ideal for larger systems
Ebb & Flow (high and low tide):
- Periodic substrate flooding