Grow Lights
6 guides in this topic
PPFD, PAR, DLI, and Lux Explained
PAR is the wavelength range, PPFD is the momentary intensity at the leaf, and DLI is the daily total — only those last two tell you what the plant actually gets.
How to Measure PPFD at Home
A smartphone camera with a white-paper diffuser can estimate PPFD within about 20% of a real quantum sensor — good enough for positioning decisions.
Grow Light Distance and Stretching
Move the light as close as the plant tolerates without stress signs, measured by PPFD at canopy height, not by a fixed hanging chart.
How to Calculate DLI (Daily Light Integral)
DLI is just PPFD multiplied by hours of light (then × 0.0036) — measure real PPFD at canopy height, multiply it out, and compare the daily total to your plant's target range instead of trusting a single reading.
Grow Light Schedules and Photoperiod Explained
Photoperiod is a signal, not a growth dial — pick a stage-appropriate schedule, keep the dark period genuinely dark and the timer reliable, and remember the daily DLI, not the clock, is what your plants actually receive.
How to Choose a Grow Light
Judge a light by its PPFD map at your hanging height and its µmol/J efficacy — wattage tells you what it costs to run, not what your plants receive.