Top Lighting, Inter-Canopy and Under-Canopy LEDs: Designing the Light Layer

Supplemental lighting positions should be selected by the canopy problem they solve. Top lights provide the primary photon source. Inter-canopy and under-canopy systems can redistribute light into areas that receive less from above.

Top lighting establishes the room baseline

Top lights should be laid out for the target canopy PPFD, uniformity, mounting height and electrical load. They remain the foundation of most indoor and greenhouse lighting strategies.

Inter-canopy lighting targets the interior

Linear fixtures placed within or alongside the canopy can add photons deeper in taller or denser crops where upper leaves intercept much of the top light.

Under-canopy lighting targets lower productive sites

Under-canopy fixtures add light below the main canopy. Their value depends on plant architecture, pruning strategy, fixture position, heat and the amount of lower growth the facility intends to maintain.

Measure before and after

Map PPFD at representative positions before adding another lighting layer. After installation, repeat the measurements and compare crop outcomes, electrical load and labour requirements.

Do not count photons twice

When several lighting layers overlap, evaluate the combined distribution at the plant rather than adding fixture PPF specifications and assuming all emitted photons reach useful tissue.

Compare PURE top, inter-canopy and under-canopy lighting systems.