Greenhouse Grow Lights

Lighting greenhouse: Essential for growth

Lighting is an essential factor for plant growth. Our greenhouses are designed to create an optimal environment for growing plants. Because natural sunlight is the cheapest source of light available, translucency of the greenhouses and greenhouse shading are important factors. However, natural sunlight is not always available in sufficient quantities or at the right time for optimal commercial products. This is where supplemental lighting with grow lights comes in handy.

Grow Light Requirements in Greenhouses

Our custom-made software CRUX, allows us to easily obtain solar radiation data from reputable sources. This enables us to quickly determine the light levels available and calculate the grow light requirements for optimal production and yields. In greenhouse technology, we consider three functions of grow light.

Supplemental Grow lighting

In greenhouses, the main source of light is the sun. The availability of the sun differs over the year periods and even between days. To have more control on the plant development and production growers apply grow lighting in order to have a sufficient sum of light during a specific period. Normally this is measured in Daily Light Integral (DLI).

Daylight Extension

Plants have a requirement to light periods to optimize the photosynthesis process within the plant. You can choose whether the “day” (light) period is extended at the beginning or at the end of the day. Growers will have their own cultivation principles that must be supported with the lighting strategy.

Use of Steer light

Steer light is the supply of specific light colors (individually or spectra) to create a specific response at plant level that is not aimed at photosynthesis. This may be to determine the shape of the plant or to stimulate a process such as flowering or the opening of the stomata.

PAR Light, Micromols and DLI

There is a lot of terminology and jargon when it comes to grow lighting. To provide clarity and enable better understanding when discussing grow lighting, the essential elements and terms are briefly explained below.

Micromoles

In the greenhouse horticulture industry, the intensity of light being exposed to the plants is measured in micromoles per second, μm/s describing the number of photons at a specific surface.

DLI - Daily Light Integral

Daily light integral (DLI) is the total sum of PAR light received each day as a function of light intensity (referred to as μmol/m²/s) and duration (day). It is expressed as moles of light (mol) per square meter (m²) per day, or moles per day(mol/m²/d). The daily light integral is connected to grow models in order to justify the output per sum of light.

PAR & Light Spectrum

Plants have a specific light spectrum that influences photosynthesis within the plant. This range of light differs from the visibility through the human eye.

In general, the light spectrum being measured for plants is referred to as Photosynthetically Active Radiation (PAR) and includes wavelengths from 400 to 700 nm. However, other wavelengths outside this spectrum range can also have a significant effect on plant growth. Far-red is the spectrum above 700nm and induces the flowering and water uptake of plants increasing fruit generation in the crop and the fresh weight, where the other side UV (A-B-C) can also have a significant effect focusing on the production of dry matter increasing taste and shelf-life (product quality) of produce.

Recently, the use of Full Spectrum, Daylight Spectrum or Sunlight Spectrum is gaining interest in the greenhouse and indoor cultivation markets. These more general light spectra, all having small deviations focusing on energy and cost efficiency, can be applied to a wider range of crops and need less tuning from the grower.

Grow light requirements per crop

Different crops have distinct lighting needs for optimal growth. Understanding these needs is crucial for a successful greenhouse and indoor growing operation. For instance, leafy greens like lettuce and herbs generally require lower light intensities, for these crops, minimal additional light could be sufficient. In contrast, fruiting plants like tomatoes and peppers need higher light intensities and a broader spectrum of light to support both vegetative growth and fruiting. For more specific details, visit the crop-specific grow light requirement guides linked here.

Cannabis Tomatoes Bell Peppers Cucumbers Egg Plant Strawberries Leafy Greens