Mounting height comes from the fixture’s PPFD distribution and target canopy intensity. There is no universal 12-, 18- or 24-inch answer because a narrow board light and a wide multi-bar fixture spread photons differently.
Look for PPFD maps at several heights and select the spacing that produces the target intensity with acceptable edge uniformity. Then verify with a PAR meter in the real room.
A fixture that only works inches above the canopy can become difficult with tall crops. Plan suspension adjustment, airflow and maintenance access.
For “How High Should Commercial LED Grow Lights Be Mounted?,” these three models give you concrete products to compare against the requirements above, instead of leaving the answer at theory.
Our strongest starting point because its bar-style led / dimmable high-output fixture format makes it relevant when translating the lighting metric above into a real fixture choice.
A useful second comparison because its multi-bar led / dimmable format makes it relevant when translating the lighting metric above into a real fixture choice.
A contrasting third option because its high-output full-spectrum led / dimmable format makes it relevant when translating the lighting metric above into a real fixture choice.