Deron Caplan + CannaCribs
Mar 18, 2025
Advanced Drip Irrigation Techniques for Cannabis Cultivation
Fundamentals of Cannabis Irrigation
Cannabis prefers a dry root zone compared to many crops.
Main risk is waterlogging, not just "overwatering."
Leads to low oxygen, pathogens (pythium, fusarium), and poor nutrient uptake.
Key Principles
Irrigate to container capacity (fully saturated, with runoff).
Allow 30–50% dryback before the next irrigation cycle.
Match pot size to plant size and growth stage to avoid waterlogging or rapid drying.
Irrigation Phases
Phase 1 (P1)
First irrigation of the day, ~30–60 mins after lights on.
Goal: Reach container capacity using multiple small "shots."
Phase 2 (P2)
Maintain container capacity with pulses every 30–60 mins.
Ends at a point that allows proper overnight dryback.
Leaching fraction: irrigate with 5–20% more than container capacity to manage EC and avoid variability.
Phase 3 (P3)
From last irrigation of P2 until next day’s P1.
Target: 30–50% dryback overnight.
Balance is key: too dry risks reduced resaturation (e.g., Rockwool), while too wet risks pathogens.
Monitoring Moisture
Manual methods: lift-and-feel, or weigh pots at saturation vs. morning.
Automated tools: volumetric moisture sensors (must be calibrated and well-placed).
Even uncalibrated, sensors can show trends over time.
Irrigation Techniques
Use drip stakes or emitters for precision.
Avoid high flow rates that cause channeling.
Use at least two stakes per pot (≥0.5 gal).
Position stakes partially above media to ensure even wetting.
Core Takeaways
Always irrigate to field/container capacity.
Ensure daily dryback to maintain root health.
Continuously adjust timing and pulses as plants grow and water use changes.