Pillar Guide
Watering and Feeding Cannabis: Water Types, EC and Schedules
Water is the delivery system for everything else. This hub covers source water chemistry, feed strength by stage, watering rhythm, and hands-off automation.
Know what is already in your water
Feed charts assume you are starting from near zero. If your tap water already reads 250 ppm, adding a full-strength feed on top of it can push you straight into nutrient burn. Measure your source water first and subtract it from your target.
Reverse osmosis gives a blank slate but strips calcium and magnesium, so RO growers must add Cal-Mag. Softened water is the one source to avoid outright — ion exchange replaces calcium with sodium, which plants do not want.
Watering rhythm beats watering volume
Roots need oxygen as much as water. The wet-then-dry cycle is what pulls fresh air into the medium. Constantly damp soil suffocates roots, invites fungus gnats and looks exactly like a nutrient deficiency.
Water until 10-20% of what you poured comes out the bottom. That runoff carries away accumulated salts and tells you your feed reached the whole root zone.
Automating it without overwatering
A drip system on a timer delivers the same measured volume at the same time every day, which is more consistent than any human. It also makes a weekend away a non-event instead of a crisis.
Fabric pots pair well with automation: they air-prune roots and drain freely, so a small overshoot in volume does not turn into standing water.
Run the numbers
Gear for this stage
Auto-Watering Drip System (6 Plant)
$96Pump, reservoir, and drip stakes so a weekend away never dries out your pots.
Breathable Fabric Pots, 5 Gal (5-Pack)
$29Air-prunes roots for a denser root ball and no circling or root rot.
Living Super Soil, 1.5 cu ft
$42Lightly amended, well-draining organic mix that feeds seedlings for weeks.
3-Part Fertilizer Set (Grow / Micro / Bloom)
$64Full veg-to-flower feeding program with a printed weekly schedule.
Every guide in this topic
Water & Nutrients
The Best Water for Cannabis: RO, Tap, Well, and Distilled Compared
Water & Nutrients
Cannabis pH Guide: Soil vs Coco vs Hydro Targets
Water & Nutrients
How Often Should You Water Cannabis? The Pot Weight Method
Water & Nutrients
NPK Explained: What Cannabis Needs at Each Stage
Water & Nutrients
Cal-Mag Deficiency: Rust Spots and Yellow Veins
Water & Nutrients
Nutrient Burn: How to Recognize It and Recover
Water & Nutrients
Flushing Before Harvest: Necessary or Myth?
Water & Nutrients
Organic vs Synthetic Nutrients: Which Should You Use?
Water & Nutrients
Runoff PPM: What Your Drainage Water Tells You
Water & Nutrients
Cannabis Watering and Feeding Schedule by Stage
Frequently asked questions
- What is the best water for growing cannabis?
- Reverse osmosis water with Cal-Mag added gives the most control. Filtered city water works well once chlorine has off-gassed. Well water is usable if you test it for hardness. Avoid softened water, which swaps calcium for sodium.
- What EC should cannabis be fed at?
- Roughly 0.6 EC for seedlings, 1.0-1.4 EC in early veg, 1.6-1.8 EC in late veg, 1.8-2.2 EC through mid flower, then taper toward plain water for the final one to two weeks.
- How often should I water cannabis plants?
- By pot weight, not by calendar. Lift the pot: water when it feels light, which is usually every one to three days in a 5-gallon fabric pot depending on plant size and climate. Always water to 10-20% runoff.