Light Deficiency (Etiolation / Stretching)
Long internodal spacing with tall, thin stems and large leaves reaching for light. The plant is not receiving enough photons (PPFD / DLI) for its growth stage. Common when seedlings or clones are under weak light, or when LEDs are dialled down or mounted too high. The first 2-3 weeks of 12/12 stretch is normal - sativa-leaning plants can double or triple in height.
What usually causes it
- Average canopy PPFD too low for the stage (<200 umol/m2/s in seedlings, <400 in veg, <600 in flower)
- Light mounted too far from canopy or driver dimmed too low
- Photoperiod issues (too long dark cycle, irregular timer)
- Sativa-dominant strain in early flower (genetic stretch - normal)
Related product categories
Terms worth knowing
Walk the questions if you are not sure this is the match. The notes above are the same ones the tool ends on.