A marijuana feeding schedule week by week pairs nutrient strength with plant stage: plain water or a quarter-strength mix in weeks 1 and 2, nitrogen-heavy feeds in weeks 3 through 6, then phosphorus and potassium from week 7 until harvest. Most growers feed at every other watering in soil and at each reservoir change in hydro. The exact numbers depend on your medium, but the shape of the curve holds for photoperiod and autoflower plants alike.
Week by week feeding chart for photoperiod plants
- Weeks 1-2 (seedling): plain water, or a quarter-strength feed at 0.4 to 0.8 EC. Roots are fragile and salts stack fast in small pots.
- Weeks 3-4 (early veg): 1.0 to 1.4 EC with a nitrogen-forward NPK near 3-1-2. Feed every other watering.
- Weeks 5-6 (late veg): 1.4 to 1.8 EC, same nitrogen push. This is the stretch window before the light flip.
- Weeks 7-8 (early flower): switch to a bloom mix near 1-3-2 and hold EC at 1.6 to 2.0. Keep a little nitrogen so leaves stay green through stretch.
- Weeks 9-10 (mid flower): 1.8 to 2.2 EC, heavy phosphorus and potassium. Buds swell and water demand peaks.
- Weeks 11-12 (late flower): drop to 1.2 to 1.6 EC. Cut nitrogen, keep potassium.
- Weeks 13-14 (flush and harvest): plain water at the right pH, then chop when trichomes turn cloudy.
Seedling stage: weeks 1 and 2
A seedling lives off the cotyledons for the first days and needs almost nothing from a bottle. Feeding too early burns root hairs and stalls growth for a week or more. If your soil has compost or an amended mix, water alone covers this stage.
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What to feed a seedling
- Plain water at pH 6.0 to 6.5 in soil, 5.7 to 6.0 in coco or hydro.
- If you feed, use one quarter of the label dose and watch for burnt tips.
- Skip bloom boosters, PK additives, and enzymes until week 3.
Vegetative stage: weeks 3 to 6
Veg is the build phase. Leaves, stems, and roots expand, and nitrogen drives that work. Aim for steady, mild feeds rather than one big dose.
Marijuana Fertilizer Schedule: Outdoor vs Indoor Picks
Nitrogen and EC targets in veg
Most cannabis nutrient lines call for an NPK near 3-1-2 or 2-1-2 during veg. In soil, run 1.0 to 1.6 EC. In coco or drain-to-waste hydro, push 1.4 to 1.8 EC. Water to 10 to 20 percent runoff so unused salts leave the pot.
How often to feed in veg
Feed, water, feed, water is the standard loop in soil. In coco, feed at every watering with a lower EC. Add cal-mag if you use reverse osmosis water or a coco mix, since both tie up calcium.
Flowering stage: weeks 7 to 12
Nutrient demand turns when the light schedule flips to 12/12. The plant stretches for two weeks, then builds flower sites. Phosphorus and potassium take over, but a hard cut of nitrogen at week 7 costs you leaves before buds finish.
Early flower (weeks 7 and 8)
Blend veg and bloom nutrients at a 50/50 ratio for the first week after the flip. Move to a full bloom mix at week 8. Hold EC near 1.6 to 2.0 and watch for clawed leaf tips, which signal too much nitrogen.
Mid flower (weeks 9 and 10)
This is the peak feed window. Raise EC to 1.8 to 2.2 and keep phosphorus and potassium high. Water use jumps, so check pots each day and feed before the medium dries past the wilt point.
Late flower (weeks 11 and 12)
Drop EC to 1.2 to 1.6 and cut nitrogen. Too much food late in flower delays ripening and leaves a harsh taste. Watch trichomes, not the calendar, when you decide to harvest.
Flush and harvest: weeks 13 and 14
A flush means plain water at the correct pH for the last 7 to 14 days. Research on flushing is thin, and some growers skip it in organic soil. If you run salt-based nutrients in hydro, a flush clears the root zone, and many growers report a cleaner burn.
How does an autoflower feeding schedule differ?
Autoflowers start flowering on their own at week 3 to 5, so the whole run lands near 10 to 12 weeks. Compress the same curve: two weeks seedling, two to three weeks veg, four to five weeks flower, one week flush. Feed lighter, since a short veg window and a small root ball limit how much salt the plant can take.
What pH and EC should you run?
- Soil: pH 6.0 to 6.8, EC 1.0 to 2.0.
- Coco coir: pH 5.8 to 6.2, EC 1.2 to 2.2.
- Hydro (DWC, drain to waste): pH 5.5 to 6.2, EC 1.0 to 2.2.
- Check runoff EC once a week. A runoff reading above your input by 0.4 points means salts have built up and the pot needs a water-only cycle.
Common feeding mistakes
- Feeding on a fixed calendar while ignoring plant size.
- Jumping EC by 0.5 or more in one step.
- Mixing nutrients at full strength in soft water without cal-mag.
- Skipping runoff in coco, which lets salt stack in the root zone.
FAQ
Do I feed every watering?
In soil, no. Alternate feed and water so roots chase moisture and salts do not stack. In coco or hydro, feed at every watering at a lower EC.
Should I feed during the flush?
No. Plain water for the final 7 to 14 days. If leaves yellow in the last week, that is normal senescence and not a sign you need more food.
Why do my leaves turn yellow in veg?
Yellow lower leaves in veg point to a nitrogen shortfall or a pH lockout. Check your input pH and runoff EC before you add more food, since a lockout looks the same as a shortage.
Can I feed more to grow bigger buds?
Past a point, more nutrients burn roots and cut yield. Bud size follows light, airflow, and genetics more than a heavy bottle dose. Raise EC in small steps and stop when leaf tips burn.