Led Grow Plant Growth Stages & LED Lighting 2 — Questions and Answers
Question 1: For autoflowering cannabis strains, what light schedule is most commonly used from seed to harvest?
- 12/12 throughout the entire life cycle
- 18/6 throughout the entire life cycle (Correct answer)
- 20/4 for veg then 12/12 for flower
- 24/0 for the entire life cycle
Correct answer: 18/6 throughout the entire life cycle
Autoflowering strains flower based on age rather than light cycles, so most growers run 18/6 throughout for maximum photosynthesis and yield.
Question 2: What is the 'canopy management' technique most important for maximizing LED grow light efficiency?
- Removing all lower leaves to prevent pest hiding spots
- Training plants to maintain an even, flat canopy at equal distance from the LED (Correct answer)
- Increasing plant density to block light from reaching the floor
- Rotating plant positions daily to equalize light exposure
Correct answer: Training plants to maintain an even, flat canopy at equal distance from the LED
Maintaining a flat, even canopy (through LST, SCROG, or topping) ensures all bud sites receive equal PPFD from the LED, maximizing yield.
Question 3: What plant symptom indicates that LED light intensity is too low during the flowering stage?
- Leaf tips curling downward (clawing)
- Loose, airy buds with extended internodal spacing (Correct answer)
- Deep green leaves with purple streaks
- Rapid leaf growth with no flower development
Correct answer: Loose, airy buds with extended internodal spacing
Insufficient PPFD during flowering results in loose, airy, low-density buds as plants lack enough energy for full trichome and bud development.
Question 4: What is the 'late flowering' LED lighting strategy some growers use in the final 2 weeks before harvest?
- Switching to a 24-hour dark period to force resin production
- Increasing red/far-red spectrum and reducing blue to maximize resin and terpene production (Correct answer)
- Reducing PPFD by 50% to slow bud growth and prevent over-ripening
- Adding UV-B light exposure to increase THC percentage
Correct answer: Increasing red/far-red spectrum and reducing blue to maximize resin and terpene production
Shifting spectrum toward red/far-red in late flowering can enhance resin production and terpene development as plants approach maturity.
Question 5: What is 'photoinhibition' and when can it occur in LED grow rooms?
- A decrease in photosynthesis efficiency caused by excessive light intensity damaging photosystems (Correct answer)
- An increase in plant growth rate triggered by very high PPFD levels
- A process where plants shut down at night to conserve energy
- A technique used to stop flowering by interrupting the dark period
Correct answer: A decrease in photosynthesis efficiency caused by excessive light intensity damaging photosystems
Photoinhibition occurs when PPFD exceeds a plant's capacity to process light, damaging photosystem II and temporarily reducing photosynthetic efficiency.
Question 6: What is the effect of maintaining plants in a 24-hour continuous light cycle on most photoperiod cannabis strains?
- Maximum vegetative growth with no negative effects
- Potential hermaphroditism, stress, and abnormal leaf growth in some strains (Correct answer)
- Immediate transition into the flowering stage
- Significantly reduced nutrient uptake leading to deficiencies
Correct answer: Potential hermaphroditism, stress, and abnormal leaf growth in some strains
Many photoperiod cannabis strains experience stress, abnormal growth, or hermaphroditism under continuous 24-hour light, as they need a dark period.
Led Grow Plant Growth Stages & LED Lighting 2
For autoflowering cannabis strains, what light schedule is most commonly used from seed to harvest?