Led Grow Plant Growth Stages & LED Lighting

Question 1

What light schedule is typically used to keep cannabis plants in the vegetative stage indoors?

Accepted Answer

18 hours light / 6 hours dark

Answer

12 hours light / 12 hours dark

Answer

16 hours light / 8 hours dark

Answer

24 hours light / 0 hours dark

Question 2

What light schedule is required to trigger flowering in photoperiod cannabis strains?

Accepted Answer

12 hours light / 12 hours dark

Answer

20 hours light / 4 hours dark

Answer

18 hours light / 6 hours dark

Answer

14 hours light / 10 hours dark

Question 3

What PPFD level is generally recommended for cannabis seedlings in their first two weeks?

Accepted Answer

50-150 µmol/m²/s

Answer

200-400 µmol/m²/s

Answer

400-600 µmol/m²/s

Answer

700-1000 µmol/m²/s

Question 4

How does increasing CO2 concentration above ambient levels (1500+ ppm) benefit plants under high-intensity LED grow lights?

Accepted Answer

It allows plants to photosynthesize at higher light intensities without reaching light saturation

Answer

It reduces the plant's water requirements by 50%

Answer

It eliminates the need for blue light in the spectrum

Answer

It replaces nitrogen fertilizer requirements during flowering

Question 5

What is 'light burn' in cannabis plants, and what causes it under LED grow lights?

Accepted Answer

Bleaching and necrosis of upper leaves caused by excessive PPFD from lights too close

Answer

A fungal disease exacerbated by high humidity and light intensity

Answer

Yellowing of lower fan leaves due to insufficient light penetration

Answer

A nutrient deficiency triggered by light-induced pH changes

Question 6

What is the 'stretch phase' in cannabis, and how should LED light intensity be managed during this period?

Accepted Answer

The first two weeks of flowering when plants rapidly elongate; maintain or slightly reduce intensity

Answer

The final two weeks of flowering when buds gain mass; maximum intensity recommended

Answer

The seedling stage before roots are established; very high intensity needed

Answer

The cloning stage after cuttings are taken; maximum blue spectrum needed