Crop-light requirement
Species, cultivar, stage, morphology, finish schedule, quality objective, natural-light history, photoperiod sensitivity, and production method define the question.
LIGHT IS QUANTITY, TIME, SPECTRUM, AND SPACE
Horticultural
Supplemental Lighting
A fixture specification is not a crop-lighting result. The useful system connects outdoor and canopy light, crop stage, photoperiod, spectrum, fixture layout, dimming, screens, power, heat, uniformity, commissioning, crop response, and economics.
5CHAPTERS4VISUAL BLOCKS2GRAPH LINKS3SOURCES
ACT / SELECTED CONCEPTHorticultural Supplemental LightingStart with the role, then move through the editorial sequence.
HOW TO READ THIS PAGE
Visual explanationA diagram or operating scene makes the relationship visible.
Structured modelA flow, comparison, capability set, or boundary map organizes the idea.
Guided explanationOriginal prose connects the concept to its operating context.
01 / Overview
Design for the light received
by the crop over time.
Natural greenhouse light changes with season, latitude, weather, glazing, structure, screens, crop height, and nearby obstructions. Supplemental lighting adds a controllable layer; it does not erase those spatial and temporal differences.
Daily light integral describes accumulated photosynthetic light rather than a single instant. It belongs beside—not in place of—photoperiod, spectrum, canopy distribution, crop response, electrical demand, fixture heat, and operating cost.
02 / Lighting loop
Measure, plan, deliver,
map, verify.
01CONTEXT / 01Define crop and natural lightSpecies, stage, crop plane, season, glazing, screens, shade, forecast, photoperiod, production objective, and energy constraints
02PLAN / 02Set the lighting strategyDaily target logic, schedule, dimming, zones, spectrum capability, blackout or screen coordination, price and demand constraints
03DELIVER / 03Control the fixturesLayout, mounting, drivers, circuits, communication, thermal state, power, transitions, interlocks, and safe maintenance
04VERIFY / 04Measure crop-plane resultsGrid mapping, sensor position, calibration, daily accumulation, uniformity, crop response, power use, drift, cleaning, and re-commissioning
03 / Lighting system
Fixture efficacy is important,
but it is not the whole installation.
Optical and spatial design
Fixture distribution, beam pattern, mounting height, crop plane, structure, screens, aisle loss, overlap, edge effects, and future crop height shape delivered uniformity.
Integrated control
Dimming, zoning, schedules, daylight response, daily accumulation, screens, climate equipment, alarms, overrides, power limits, and records connect lighting with the greenhouse.
Commissioning and economics
Crop-plane mapping, electrical measurement, thermal checks, cleaning, depreciation, electricity, demand, labor, yield, timing, quality, and market value determine whether performance is useful.
04 / Light concepts
Four light questions
must not collapse into one number.
ConceptQuestion answeredDoes not answer
Instantaneous crop-plane intensityHow much photosynthetic light reaches a location now?The total day, distribution, spectrum, or crop response
Daily light integralHow much photosynthetic light accumulated over the day?Photoperiod timing, spectrum, spatial uniformity, or economics
PhotoperiodHow long is the defined light or dark period?How many photons arrived or where they reached the crop
SpectrumHow is radiant output distributed by wavelength?Delivered quantity, fixture layout, crop universality, or financial return
05 / Boundaries
A bright greenhouse can still have
a poor lighting system.
One sensor reading is not a lighting map.Crop-plane height, time, location, orientation, calibration, spectral response, shading, natural light, and measurement grid all influence interpretation.
A crop response is not universal.Species, cultivar, stage, density, climate, nutrition, carbon-dioxide context, pest pressure, production system, and market objective can change the value of a lighting strategy.
More light is not automatically more profit.Capital, electricity, demand, heat, controls, maintenance, labor, crop timing, yield, quality, price, risk, and opportunity cost belong in the same decision.
06 / Connections
See the system around this concept.
Follow incoming and outgoing relationship records to understand what supplies, informs, enables, coordinates with, or extends this technology in the published knowledge graph.
Relationship radar / published edges2 records / 2 neighboring systems
Incoming01records point toward this concept
act roleHorticultural Supplemental LightingSelected technology
Outgoing01records point from this concept
02connections visible
act / Controlled-environment actuationGreenhouse Climate Control ↗coordinates crop climate and energy state with
Integrated greenhouse operation can coordinate supplemental lighting with natural light, screens, temperature, humidity, crop stage, power limits, and the resulting thermal load.
decide / Production resource managementGreenhouse Energy Management ↗adds controllable electrical demand to
Supplemental lighting adds fixture, zone, schedule, intensity context, crop stage, daylight interaction, heat, electrical demand, maintenance, and measurement boundaries to greenhouse energy management.
2CONNECTED ROUTES4–4STEP POSITIONS15ROUTE SOURCE LINKS
Operating practice
From greenhouse observation to crop control
Follow one protected-crop production loop from representative environmental and root-zone evidence through coordinated climate, light, and fertigation action, then into daily flower-production practice.
- 01 / OBSERVEMap the greenhouse environmentTechnology→
- 02 / ROOT ZONERead the container as a dynamic reservoirTechnology→
- 03 / CLIMATECoordinate the atmospheric control loopTechnology→
- 04 / LIGHTBuild the crop's light dayTechnology→
- 05 / WATER + NUTRIENTSClose the fertigation loopTechnology→
- 06 / PRACTICERun the flower-production routineField guide
CURRENT POSITION04
04 / LIGHT
Open the complete route ↗Build the crop's light day
Separate instantaneous intensity, daily accumulation, photoperiod, spectrum, spatial uniformity, commissioning, and economics.
07 / Evidence
Primary sources.
This briefing uses Purdue daily-light guidance and Cornell and Penn State controlled-environment resources. It does not provide crop recipes, target quantities, spectral prescriptions, fixture recommendations, or return-on-investment claims.
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Measuring Daily Light Integral (DLI)Purdue University Extension · Accessed 2026-07-20