Led Grow Troubleshooting LED Grow Lights 2

Question 1

Upper leaves of cannabis plants directly below the LED are turning pale yellow or white despite correct height. What is the most likely diagnosis?

Accepted Answer

Light bleaching (photobleaching) from excessive PPFD reaching the uppermost leaves

Answer

Photobleaching occurs when PPFD is too high for the plant tissue to handle — the chlorophyll is destroyed and leaves turn pale yellow or white near the light source.

Question 2

What is 'nutrient lockout' and how can it be mistakenly attributed to LED grow light problems?

Accepted Answer

A soil/root condition where pH imbalance prevents nutrient uptake, causing deficiency symptoms that look like light stress

Answer

Nutrient lockout (caused by pH problems) creates deficiency symptoms like yellowing and stunted growth that can be mistaken for light stress or insufficient LED intensity.

Question 3

A grower replaces their old LED grow light with a new, more powerful model but notices no yield improvement. What is the most likely oversight?

Accepted Answer

The new light was not repositioned to match its different beam angle and recommended hanging height

Answer

A more powerful LED hung at the old light's height may be outside its optimal distance range, producing suboptimal PPFD distribution and wasting the upgrade.

Question 4

What does 'hot spot' troubleshooting involve in an LED grow room?

Accepted Answer

Using a PAR meter to map PPFD across the canopy and identify areas of excessively high or uneven light intensity

Answer

Hot spot mapping involves measuring PPFD at multiple canopy points to identify areas where light intensity is significantly higher than target, indicating poor light distribution.

Question 5

What is the most effective way to diagnose whether slow plant growth in an LED grow room is caused by insufficient light rather than other factors?

Accepted Answer

Measure actual PPFD at canopy level and compare to stage-appropriate targets using a quantum meter

Answer

A quantum/PAR meter provides objective PPFD measurements that can be compared against known targets for each growth stage, directly confirming whether light is the limiting factor.

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Led Grow Troubleshooting LED Grow Lights 2