Cannabis Vegetative Stage Water and Feeding
Water cannabis in the vegetative stage when the top 1 to 2 inches of the medium feel dry. Feed a nitrogen-heavy mix at an EC of 1.2 to 1.6, or 600 to 800 PPM on the 500 scale. Hold pH at 6.0 to 6.5 in soil and 5.8 to 6.2 in coco or hydro. The vegetative stage runs about 3 to 8 weeks indoors. Plants in this window build roots, stems, and leaves before flowering starts.
How Much Water Per Plant
Give 10 to 20 percent of the pot volume at each watering. A 5-gallon pot takes 0.5 to 1 gallon. Water until 10 to 20 percent of that volume drains from the bottom. Runoff pushes salt buildup out of the root zone.
How to Shorten the Cannabis Vegetative Stage: A Comprehensive Guide
Pot weight is a reliable gauge. Lift the pot after a full watering, then again two days later. Water when the pot feels light, not on a fixed calendar.
Watering Frequency by Medium
- Soil: every 2 to 3 days in a 5-gallon pot at 75 F.
- Coco coir: once per day, or twice per day in late veg.
- Peat mixes: every 2 to 4 days.
- Deep water culture: continuous flow, with the water level 1 inch below the net pot.
Roots need oxygen between waterings. A medium that stays wet for 5 days or more slows growth and raises root rot risk.
What Temperature for Cannabis Veg Stage
Vegetative Nutrient Targets
Nitrogen drives leaf and stem growth in veg. A common veg ratio is 3-2-1 N-P-K, or a two-part base at equal parts. Numbers to target:
- EC 1.2 to 1.6 in week 2 and 3; 1.6 to 2.0 in late veg for fast plants.
- PPM 600 to 800 (500 scale) in mid veg.
- Calcium and magnesium: 1 to 2 ml per gallon of calmag in coco or with reverse-osmosis water.
- Water temperature: 65 to 70 F.
Mix nutrients at full strength after the plant has 4 to 5 nodes. Seedlings and clones take quarter to half strength for the first 10 days.
Signs of Too Much or Too Little Water
- Drooping leaves with stiff stems: dry medium.
- Drooping leaves with soft stems and heavy pots: overwatering.
- Yellow lower leaves: nitrogen shortage or pH drift.
- Leaf tips that curl down and burn: nutrient strength too high. Cut EC by 0.2 to 0.4.
Environment for Veg
- Temperature: 68 to 78 F at canopy level.
- Relative humidity: 55 to 70 percent.
- VPD: 0.8 to 1.1 kPa.
- Light: 18 hours on, 6 hours off; PPFD 400 to 600; DLI 25 to 40 mol per square meter per day.
- Air movement: one oscillating fan per 4 square feet of canopy.
Feeding Schedule Example
Week 1: plain water at pH 6.0 to 6.5, no nutrients. Week 2: half-strength base nutrients, EC 0.8. Week 3: full veg strength, EC 1.2 to 1.4. Week 4 and later: EC 1.6 to 2.0 with calmag. Flush with plain pH-adjusted water every 2 to 3 weeks if runoff EC climbs above the input EC.
Exact values vary with strain, pot size, and climate. Measure runoff EC and pH to adjust.