Why is light important for hydroponic plants?
The energy of green plants comes from photosynthesis. The leaves contain cells called chloroplasts, which contain a green pigment: the famous chlorophyll. It is the reaction of this pigment with light that transforms the sugar in the sap into energy, which allows the plant to grow.
However, not all light is suitable: it must have the right light spectrum. Chlorophyll does not work well with green and yellow wavelengths. It works mostly with red and blue wavelengths. Note that it’s not just about the visible color. The red color tells plants the number and size of leaves and the blue color when to bloom. (McCallister, A. 2018) Each plant has different needs in this regard.
Finally, keep in mind that a plant also needs to “sleep”. So ideally, you should program the lighting to turn off to mimic “night” for the plants. Plants may need less than 12 hours, 12 hours or 6-10 hours of “night”.
The different types of horticultural lighting
Your hydroponic horticultural farm will generally be indoors. If the natural light is not enough, you can choose to illuminate it with an artificial light source to promote its growth. There are several types:
- Incandescent or halogen lighting. These are the most common lamps, but they are not recommended for horticulture, as they generate too much heat. They are also not very energy efficient. They are in all respects less interesting than fluorescent bulbs.
- Fluorescent lighting is quite common and full spectrum tubes are readily available. They can have a compact format, called “CFL” (Compact Fluorescent Lightbulb).
- LED lighting (light-emitting diodes). This is one of the most popular lighting: even if they are more expensive than the others, they have the best energy efficiency, longevity and produce little heat. It is even possible to generate red and blue color.
- High pressure sodium (HPS) bulbs.
The important variables are
- the intensity of the luminosity
- the durability of the bulbs. Typically, LEDs are particularly durable. Fluorescent tubes are nearly 10 times more durable than incandescent bulbs.
- heat generation
Accessories for your hydroponic horticultural lighting
Several accessories optimize the efficiency of your horticultural lighting:
- The reflector hood. This is a reflective surface that will allow you to focus your light on your crop, which optimizes the efficiency of your lighting.
- A timer. Inexpensive, but essential, it allows you to adjust the duration of exposure of your crop.