Horticulture Grow lights - Light requirements of plants

Hydroponics, greenhouses, indoor gardening, growing aquatic plants, food production and plants propagation – all of these fields use grow lights. Mostly, it is done on an industrial level, although, non-professional, domestic gardeners are also in a habit of using grow lights.

Increasing light efficiency is often of vital importance for the growers, as the farther the grow light is from the plants, the more of it is lost. Many methods, techniques, and tricks are employed nowadays by the growers to achieve this goal: it is possible to use light reflectors, to whitewash the walls or cover them with reflective materials, to group plants close together, or to move lamps closer to them. For example, incandescent lamps may be placed as close as 24 inches to the plants, while other types of light (those that produce less heat) may be about 4 inches close to the plants.

As for the reflective materials, white and black plastic sheeting is the most common option. The black side is turned towards the walls and the white one faces the plants and works to reflect the light. Using a white paint gardeners choose those with the highest content of titanium dioxide to increase its reflexive abilities. Other types of sheeting include Foylon (foil-laminated fabric), Mylar, or Astrofoil (heat and light reflective sheeting).

Light requirements of plants

It is the real science of adjusting light to the requirements of peculiar plants. Indeed, various herbs need different amount of lighting, and that used in the indoor gardening should mimic that of the natural surrounding. Furthermore, along with the kind of the plant grown one should take into account its growth stage and even size. Thus, having provided optimal light, a gardener may expect the best yields.

Let us say, the richest crops of vegetables is possible to achieve using MH-lamps or fluorescent lamps, which resemble full sunlight. Foliage plants may grow best in the shade, thus, incandescent lamps may be enough for them.

The growers must not forget to allow the plants to “rest” ensuring dark periods (similar to the night in the natural environment). Some plants need many hours of light and short dark periods, while others flourish when both periods are equal.

To sum it up, it is necessary to mention about one more important for the indoor gardening notion: it is light density – the amount of light falling on a surface, which is measured in lux. One lux is equal to one lumen of light falling on a square meter. To make understanding easier, a brightly illuminated office will have approximately 400 lux, while light density of a standard candle on one square foot will reach about 10,76 lux.

Horticulture Grow lights comparison

An interesting note about PAR watts and lumens for MH and HPS lamps is that the correlation between the two is over 97%. Meaning that for HPS and MH lights (remember the very restricted sample used here) on average there is less than 3% variance when estimating PAR watts from lumens. But remember that is an average and some lamps the difference may be much more.

An interesting note about PAR watts and lumens for MH and HPS lamps is that the correlation between the two is over 97%. Meaning that for HPS and MH lights (remember the very restricted sample used here) on average there is less than 3% variance when estimating PAR watts from lumens. But remember that is an average and some lamps the difference may be much more.