Plant lighting - Your Quickstart Guide

Your quickstart guide to plant lighting

Plants need light. Just which one? The best thing for any plant is natural sunlight. Since this is not available in indoor gardening, the question of a worthy substitute arises. Basically important for a plant light is the power (Watt) of the ballast/lamp and the contained color spectrum, or color temperature (°Kelvin).

For example, a 250 W lamp will not generate as much growth as one with 400 W and a bulb that is closer to the natural daylight spectrum (approx. 6500° K) will allow far more natural growth than, for example, a very "warm" bulb (e.g.: 2500° K). On the other hand, the light color can be used to specifically control plant growth. For example, a higher proportion of red in the light stimulates flowering and fruiting in many species, while more blue stimulates leaf growth.

Which light source should it be?

First of all, the sodium vapor lamps (also: HPS) should be mentioned; with a high proportion of yellow and red light, they are ideally suited to bring most crops through the growth, flowering and fruiting phase. In addition, HPS are very efficient light sources; A large portion of the energy consumed is converted into light that can be used by the plant (a lot of lumens per watt (lm/W)). MetalHalides (MH) are related to HPS in the way they work, but emit much more in the blue range.

This makes them the optimal light for the growth phase, for example: Promote leaf growth and strong side shoots. Energy saving lamps (ESL) are nowadays available in many different color temperatures (from approx. 2500°K-6500°K). The luminous efficacy (lm/W) is not as high as with NDL, but they impress with low energy consumption.

Day and night in the box. Sensible planning of light cycles.

The cycle of day and night determines almost everything in the life of a plant. Depending on the species and the place of origin, plants need different amounts of light per day, but for almost all plants the light cycle also controls the different growth stages.

Where orchids, for example, prefer a constant day length (and grow and bloom accordingly year-round), many cultivated plants (tomatoes, for example) require alternating phases of long days, during which the plant mainly grows, and shorter days, which initiate flowering and eventually fruiting. Accordingly, the home gardener can consciously use the light cycle to control the phases of growth.

Ballast, reflector, light source Only together does it get really bright.

When coordinating a lighting system that exactly fits one's own needs, a lot of care should be taken with the appropriate, individual components.
For example, HPS and MH lamps work with a ballast (VSG), which makes the current from the line available to the lamp. In ESL lamps, the VSG is already integrated in the housing. Reflectors are used to direct the light emitted by the lamp in all directions to where it is needed - to the plants.
In this way, a good reflector can considerably increase the luminous efficacy of the lamp. And in the long run, that means more growth with the same power consumption.

LED outshines everything else

LED (Light Emitting Diode) convert the current flowing through them into light very efficiently, and in terms of efficiency they outshine any previous technology. The biggest advantage of LED grow lamps, however, is the spectrum, which can be precisely adjusted to the requirements of photosynthesis.

Unlike an NDL, for example, an LED can emit red, blue and other wavelengths simultaneously. A Grow LED is therefore not only more efficient in the "production" of the light beams, but the light beams themselves can be absorbed by the plants much better and more effectively, which leads to even better yields at the same electricity costs.
A modern Grow LED has about 30% more light output than a conventional NDL at the same power consumption, which means that the acquisition costs are quickly amortized.