How Often Should You Fertilize Weed Plants?
In soil, feed every other watering. That works out to one feeding every 7 to 14 days. In coco coir or hydroponics, feed at every watering with a weaker mix. Organic slow-release amendments go in every 3 to 4 weeks.
marijuana feeding schedule week by week
Those numbers are starting points. Pot size, light intensity, water volume and plant age all move the schedule.
What Nutrients Do Cannabis Plants Need at Each Stage?
Frequency by Growing Medium
- Amended living soil: reamend every 3 to 4 weeks. Water plain in between.
- Plain potting soil: feed every second watering. Do not feed on dry soil.
- Coco coir: feed every watering. Coco holds no nutrients, so plain water starves the plant.
- Deep water culture and other hydro: change the reservoir every 7 to 10 days and reset the nutrient strength.
Frequency by Growth Stage
Week 1 to 3 from seed: no fertilizer, or one quarter strength. The cotyledons carry the seedling.
Vegetative stage: nitrogen demand is highest. Feed every 7 to 10 days in soil. Target a nutrient strength of 1.3 to 1.8 EC in coco.
Flowering weeks 1 to 3: keep the vegetative mix. The plant stretches and still uses nitrogen.
Flowering weeks 4 to 8: shift to a bloom mix with more phosphorus and potassium. Feed once per week.
Final 7 to 14 days: many growers water plain. Data on flushing is mixed. It does not remove nutrients stored in leaf tissue.
Read the Plant Before the Calendar
Plants show the answer faster than a schedule does.
- Dark green leaves with tips curling down: nitrogen is too high. Skip one feeding.
- Pale lower leaves turning yellow: nitrogen is low. Feed at full strength.
- Brown, crisp leaf tips: salt buildup. Water to runoff with plain water and recheck.
- Purple stems with slow growth: cold root zone or low phosphorus. Check temperature first.
Measure runoff. If runoff EC runs more than 0.4 above the input EC, salts are collecting in the medium. Water plain until the numbers match.
A Soil Schedule That Works
- Day 1: water with nutrients to 10 to 20 percent runoff.
- Day 2 to 3: let the top 2 inches of soil dry.
- Day 4: water plain, same volume.
- Day 5 to 6: dry back.
- Day 7: repeat from step one.
Cut the dose in half for autoflowers and for plants under 300 PPFD of light.
What Moves the Schedule
- Pot size: a 3 gallon pot dries faster than a 10 gallon pot. Faster dry back means more feedings.
- Temperature and humidity: a warm, dry room pushes water use up.
- Light: high PPFD raises demand for calcium and magnesium.
- Water source: hard tap water carries calcium and magnesium. Cut the calmag dose.
Record each feeding and the runoff EC. A written log beats memory after week 6.