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Traditional incandescent lamps are used by many vegetable growers to illuminate seedlings, but they are of no use. The emitted yellow-orange glow does not help the plants develop. The entire useful spectrum is obtained from LEDs or phytolamps. The disadvantage is the high cost of lighting equipment. A full-fledged replacement can be fluorescent lamps for seedlings, emitting the entire necessary light spectrum.
Light source device
In everyday life, fluorescent lamps are known as fluorescent lamps. The name comes from the white glow. The device consists of a housing with a diffuser. A glass tube, sealed at both ends and operated by a choke, acts as a lamp. The inner surface of the glass walls is covered with a white coating – a phosphor. A base is fixed at both ends of the tube. Through its contacts, voltage is applied to the filament. The pressurized interior is filled with argon and a small amount of mercury.
Fluorescent and traditional incandescent lamps have one thing in common – a tungsten filament. When voltage is applied, the spiral radiates heat, which contributes to the formation of UV radiation in argon and mercury vapor. For the human eye, the rays are not visible, but the plants benefit. The phosphor coating contains phosphorus substances that form the spectrum and enhance the glow. Thanks to additional components, the fluorescent tube glows 5 times stronger than a traditional incandescent lamp.
Seedling response to light
Under natural conditions, plants develop under sunlight. Seedlings are grown on a windowsill or greenhouse. Daylight penetrating glass is not enough. It should be noted that the cultivation of seedlings falls on a period of short daylight hours, and artificial lighting is indispensable.
Traditional incandescent lamps emit a yellow-orange light that is useless for plants. The absence of UV rays inhibits the growth of seedlings and the process of photosynthesis. As a result, unfriendly shoots are observed, withering shoots on long thin legs. In the fall, such planting material will produce a poor harvest, and during the growing season, the crops will get sick.
When seedlings are illuminated with fluorescent lamps, conditions are created that are as close to nature as possible. There are two important colors in UV rays: blue and red. The spectrum useful for the plant suppresses the harmful ranges of other colors and promotes the full development of plants.
Useful and useless spectra
The full spectrum of colors is present in the solar color, and it has the most positive effect on the vital activity of plants. Fluorescent tubes are able to provide seedlings with blue and red light. These colors are maximally absorbed by plants and benefit:
- Blue color promotes proper cell development. The stem of the plant does not stretch, but thickens and grows stronger.
- Red color is useful for germinating seeds, and also accelerates the formation of inflorescences.
Red and blue are optimal for seedlings, but the percentage of benefit depends on absorption. There is such a thing as distraction. Direct rays absorb foliage worse. If you use a matte reflector with a fluorescent lamp, the light becomes diffused. Rays of red and green become more favorable for absorption by vegetation.
Varieties of light sources
Considering which fluorescent lamp is best for seedlings, it is worth considering that the light sources of this group are divided into two types.
Traditional daylight sources
The simplest and cheapest option are economy class fluorescent lamps for seedlings used for indoor lighting. They emit daylight with a limited amount of blue and red. Products differ in shape. The traditional “housekeeper” in the form of a spiral or U-shaped tubes, twisted into a chandelier cartridge, similarly from this group. However, this option is not suitable for growing planting material due to the small area of illumination.
The best option is a tube. Lamps are produced in different lengths, which allows them to be distributed over the entire rack. The disadvantage of the light source is low power. You have to hang fluorescent lamps for tomato seedlings or other garden crops as close to the plants as possible. In terms of lighting area, the tube is able to replace 2-3 “housekeepers”.
Phytoluminescent light sources
If you decide to seriously start growing seedlings, it is preferable to acquire phytoluminescent light sources. The lamps are specially designed to illuminate plants in greenhouses. A feature of the product is an unusual spectrum of luminescence, as close as possible in terms of characteristics to the sun’s rays. The composition is dominated by pink and lilac color. For human vision, radiation creates discomfort, and benefits plants.
The advantage of phytolamps is low power consumption, long service life and safe use. Due to its small size, the phytoluminescent lamp can be placed in a limited space, and it illuminates a large area.
The main disadvantage is the spectrum that is uncomfortable for vision. When growing seedlings inside a living room, you will have to take care of reflectors and protective partitions. The design should maximally direct the glow to the planting material, and not into the eyes of the residents of the house.
Among the popular manufacturers of phytoluminescent lamps are the Osram, Enrich and Paulmann brands. Devices for illumination are available in different capacities and almost all are equipped with reflectors.
Organization of illumination
To correctly determine which fluorescent lamps are suitable for seedlings, you need to know what optimal lighting is acceptable for growing crops.
Brightness
Every culture is different in its sensitivity to light. Some people like bright lights, while others like soft lights. It is unprofitable to buy a lot of lamps that differ in power to illuminate different seedlings. Brightness is best adjusted by the height of the hanging fixtures.
Cucumbers or cabbages love direct sunlight. Lighting devices are removed from the tops of the seedlings at a distance of 20 cm. Eggplants, tomatoes and peppers experience discomfort under bright lighting. Fluorescent lamps move away from the tops of the seedlings at a distance of up to 50 cm.
The height of the lamps is constantly monitored. Seedlings grow rapidly and their tops should not come close to a critical distance from the lamps.
Backlight duration
At different ages, planting material requires a certain duration of illumination. In winter, in cloudy weather, fluorescent lighting is turned on for 18 hours. On sunny days, the backlight is turned off. Plants need to get used to natural light. The duration of artificial lighting is reduced to 12 hours.
The duration of illumination depends on the age of the plants. After sowing the seeds over the boxes, turn on the light around the clock to speed up the germination. Germinated plants need rest at night. Constant lighting will not be in favor. A good result is the use of lamps with different characteristics. The combination of lighting devices allows you to get a spectrum that is as close as possible to the sun’s rays.
The video talks about the effect of light on seedlings:
Do-it-yourself backlighting
In the manufacture of lighting, it is desirable to choose the shelves of the racks and fluorescent tubes of the same length. The optimal size is 1 m. It is better to use factory-made fixtures. The devices are compact, equipped with a switch, all electrical elements are hidden under the casing, and the glass tube is closed with a plastic matte diffuser.
In a home-made backlight, they must hide the junction of the base with the cartridge with a casing. Wiring is laid along the rails of the rack. The throttle is installed in the box further from the lamps, so that when watering the seedlings, the water does not cause a short circuit.
Fix the backlight on the underside of the shelf of the upper tier of the rack. The glass surface of the tube must not come into contact with any objects. On wide shelves, it is optimal to install 2 lamps at the edges. If the brightness of the backlight will be adjusted by a dimmer, the appliances can be fixed to the shelves with rigid steel tapes. Otherwise, the lamps are hung on ropes to adjust the height.
When organizing the illumination of seedlings, one must remember about electrical safety. Water that has fallen on the lighting fixture during irrigation will create a short circuit. There is even a threat of destruction of the glass tube, where inside there is mercury dangerous for humans.