LED Grow Glossary

This is the unit that measures a LED lamp’s efficiency: how many photons useful to plants (µmol) are produced for every joule of electrical energy consumed. The higher it is, the better the lamp at equal power consumption. A good modern LED lamp exceeds 2.5 µmol/J; the best reach 3.0–3.2 µmol/J.

The photosynthetic photon flux: the total quantity of PAR photons emitted by the lamp every second, regardless of direction. It doesn’t measure how many photons reach the plant, but how many are produced in total. It’s useful for comparing lamps in the same category.

The photosynthetic photon flux density: how many PAR photons reach one square meter of canopy every second. It’s the most important measure for understanding how much light the plant actually receives. It depends on lamp power, mounting height and coverage area.

The daily light integral: the total quantity of PAR photons received by one square meter of canopy over 24 hours. It’s the “cumulative” measure that really counts for plant growth. Calculated as: DLI = PPFD × hours of light × 3600 / 1,000,000.

Photosynthetically active radiation: the portion of the electromagnetic spectrum (400–700 nanometers) that plants use for photosynthesis. It includes blue (400–500 nm), green (500–600 nm) and red (600–700 nm). Only light in this range is counted in PPF and PPFD measurements.

Lumens (lm) measure light as perceived by the human eye: they penalize blue and red, which plants love the most. µmol/s (PPF) measure light useful for photosynthesis without spectral bias. A lamp with high photosynthetic efficiency can have few lumens but a very high PPF. Never use lumens to choose a grow lamp.

A “full spectrum” lamp covers all the PAR spectrum bands a plant needs, from vegetative growth to flowering. It emulates natural sunlight with a mix of wavelengths: blue 400–500 nm for leaf growth, green 500–600 nm for canopy penetration, red 600–700 nm for flowering.

Measures the “tone” of white light: low values (2700–3000K) give warm/yellow light, high values (5000–6500K) give cool/bluish light. For indoor cultivation, 3000K–4000K is typically used: it covers both vegetative and flowering well without needing to change lamps.

The 660-nanometer wavelength is the absorption peak of the chlorophyll A photoreceptor. The SMD3535 660nm red diodes added to the S Line Foldable’s 4000K white LEDs specifically boost the physiological response during flowering, increasing flower and fruit formation.

The name ORTOLED uses for an agriculture-optimized spectrum that covers the entire PAR band (400–700 nm) with emphasis on the wavelengths most effective for photosynthesis (blue 450 nm, red 660 nm), while still maintaining good vegetative performance.

The plant “canopy” formed by the uppermost leaves, the area that directly receives light from the lamp. PPFD is always measured at canopy level. Canopy penetration refers to light’s ability to reach inner leaves and fruit, not just the surface ones.

Light emitting diode: a semiconductor that converts electrical energy directly into light with high efficiency. Unlike traditional lamps (HPS, MH), it doesn’t burn a gas or filament — light is emitted at the atomic level. This explains its very high efficiency (up to 3+ µmol/J), long life (50,000+ hours) and the absence of harmful UV/IR rays in grow versions.

The Samsung-made LED chips most widely used in professional grow lamps. The LM301H is the high-efficiency EVO version (up to 3.1 µmol/J per chip), the LM301B is the standard version. Both are small SMD chips that allow high density on the PCB, a 4000K white spectrum optimized for photosynthesis, and a certified long lifespan.

The electronic component that converts the mains alternating current (AC) into direct current (DC) at a constant voltage to power the LEDs. Driver quality determines the lamp’s stability, efficiency and lifespan. An external driver (like Sosen or Meanwell) is separate from the light head; an integrated driver is built into the lamp body.

A system for controlling light intensity via an analog 0 to 10 Volt signal: 0V = off (or minimum intensity), 10V = maximum power. It’s the industry standard for professional grow lamps: compatible with almost all controllers, manual potentiometers and automation systems. It lets you adapt intensity to the different growth stages.

A LED lamp format where chips are evenly distributed across a single flat, high-density panel (PCB). As opposed to the “bar” (linear strip) or “COB” (chip-on-board) format. Advantages of QB: even distribution with no hot spots, wide emission angle, low profile. It’s the preferred format for square grow boxes.

LED technology where many microscopic chips are bonded directly onto a substrate (board) in a single compact area, creating a high-intensity point light source. Excellent canopy penetration for central areas, but less uniform over large surfaces compared to Quantum Boards.

A heat dissipation system that doesn’t use mechanical fans. Heat generated by the LEDs is conducted through the PCB to an aluminum heatsink that disperses it into the air through natural convection. Advantages: silent (0 dB), zero extra power draw, no risk of mechanical failure. Requirement: good ventilation in the grow environment.

Industry standard for measuring a LED lamp’s lifespan: the number of operating hours after which luminous flux drops to 70% of its initial value. Samsung LEDs certified L70 at 50,000 hours means that after 50,000 hours of operation, the lamp still emits at least 70% of its original light output.

Enclosed spaces for indoor cultivation. A grow box is a rigid box lined on the inside with reflective material. A grow tent is a structure with a metal frame and a silver interior liner, more flexible and easier to assemble. Both create a controlled environment for light, temperature and humidity.

A room or space dedicated entirely to indoor cultivation, larger than a grow tent. It requires more structured ventilation, dehumidification and temperature control systems. Professional lamps like the S Line Foldable are designed for grow rooms from 2 m² to over 20 m².

The two main phases of the indoor plant growth cycle. The vegetative phase (18h light / 6h dark) favors leaf and structural growth — requires PPFD 200–500 µmol/m²/s. The flowering phase (12h/12h) induces flower and fruit formation — requires PPFD 600–1000 µmol/m²/s.

The vapour pressure deficit: measures the difference between the water vapour pressure inside the leaf and that of the surrounding air. An optimal VPD (0.8–1.2 kPa during vegetative, 1.0–1.5 kPa during flowering) maximizes plant transpiration and CO₂ uptake. LED lamps produce less radiant heat than HPS, making VPD control easier.

HPS (high pressure sodium) is the traditional lighting technology for indoor cultivation. Typical efficiency: 1.0–1.5 µmol/J. Modern LED reaches 2.7–3.1 µmol/J: at equal photon flux it consumes 40–60% less. Additionally, HPS emits a lot of infrared light (heat), raises grow room temperature and requires a more powerful cooling system.

A feature of advanced controllers that simulates sunrise and sunset: lamp intensity gradually increases at the start of the photoperiod and decreases at the end, instead of switching abruptly from 0 to 100%. It reduces plant stress and improves physiological rhythms. Available on the EC4330 controller, compatible with all ORTOLED lamps.

The IEC 60529 standard that classifies a device’s degree of protection against the ingress of solids (dust) and liquids (water). The code consists of two digits: the first indicates protection against solids (0–6), the second against liquids (0–9). IP65 = total dust protection (6) + resistance to direct water jets (5).

The CE marking indicates that a product complies with the applicable European directives (electrical safety, electromagnetic compatibility, etc.) and can be freely marketed within the EU. It’s not a quality mark but a minimum legal requirement for sale in Europe.

A European directive that restricts the use of hazardous substances (lead, mercury, cadmium, etc.) in electrical and electronic products. RoHS certification ensures the lamp doesn’t contain toxic materials, important both for user safety and end-of-life disposal.

Electromagnetic compatibility certification ensures the device doesn’t emit electromagnetic interference that disrupts other equipment, and that it’s immune to external interference. Important in grow rooms where lamps, fans, pumps and control systems coexist.

The alternating voltage range accepted by the lamp’s power supply. A driver with a universal 110–277V input works on both European grids (220–230V) and American/Japanese grids (110–120V), without adapters or special configuration. All ORTOLED ECO Series lamps accept 110–277V AC.