Vegetative Growth
Part of the free Stevie Weedseed grow guide. No paywall, no account, written by a working grower.
What Happens in Veg
The plant shifts from survival mode to growth mode. Leaves multiply, stems thicken, branches develop, and the root system expands rapidly. This is where you build the structure that will hold your buds.
Plants can double or triple in size during veg. Healthy veg means a big harvest.
Plants can double or triple in size during veg. Healthy veg means a big harvest.
Light Schedule
Most growers use 18/6 (18 hours light, 6 hours dark). Some use 20/4 for faster growth. 24/0 works but gives plants no rest.
PPFD target: 400-600 μmol/m²/s.
DLI target: 25-40 mol/m²/day (up to 50 with CO2).
LED distance: 18-24 inches above canopy.
Check your DLI with the Calculator →
PPFD target: 400-600 μmol/m²/s.
DLI target: 25-40 mol/m²/day (up to 50 with CO2).
LED distance: 18-24 inches above canopy.
Check your DLI with the Calculator →
Watering in Veg
As plants grow, watering becomes deeper but less frequent. Water until 10-20% runoff comes from the bottom of the pot, then let the soil partially dry.
The lift test: pick up the pot. Heavy means do not water. Light means it is time to water. This simple test prevents 90% of watering problems.
The lift test: pick up the pot. Heavy means do not water. Light means it is time to water. This simple test prevents 90% of watering problems.
Nutrients
Veg plants need higher nitrogen (N). Look for nutrient formulas labeled "Grow" or "Veg."
NPK target: roughly a 3-1-2 ratio. Start at half strength and increase gradually.
Signs of nutrient burn: brown leaf tips, dark green leaves, leaf clawing downward.
Signs of deficiency: yellowing lower leaves (nitrogen), slow growth.
Use the NPK Calculator →
NPK target: roughly a 3-1-2 ratio. Start at half strength and increase gradually.
Signs of nutrient burn: brown leaf tips, dark green leaves, leaf clawing downward.
Signs of deficiency: yellowing lower leaves (nitrogen), slow growth.
Use the NPK Calculator →
How Long to Veg
You control this. Indoor growers choose when to flip to flower.
2-4 weeks veg gives small plants (good for Sea of Green).
4-8 weeks gives medium plants (most common).
8+ weeks gives large plants (maximize yield per plant).
Critical rule: Cannabis can double in size after you flip to flower (the "stretch"). Plan your veg time so plants do not outgrow your space.
2-4 weeks veg gives small plants (good for Sea of Green).
4-8 weeks gives medium plants (most common).
8+ weeks gives large plants (maximize yield per plant).
Critical rule: Cannabis can double in size after you flip to flower (the "stretch"). Plan your veg time so plants do not outgrow your space.