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The Right Phytolamp - Choosing A Lighting Device For Additional Lighting Of Plants

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Wise nature has thought of everything to the smallest detail - sunlight provides all the needs of plants in the best way, activating germination of seeds, seedling growth, flowering and fruit setting. But when we put green pets in unnatural conditions, away from their usual environment, and with a short daylight period in the cold, we take on a very difficult task. One of the most important factors in the successful growth and development of plants is optimal light. What phytolamp to choose to provide it? In this article we deal with the main characteristics of lighting devices in order to understand which one is required in each specific case.

The right phytolamp - choosing a lighting device for additional lighting of plants
The right phytolamp - choosing lighting device for additional lighting of plants. © HYVE Crowd

The importance of correct lighting for plants

It would seem that additional lighting of plants indoors should not cause any special questions: you should allocate a personal lamp to a flower and the result will be excellent. But that's not quite true.

Light is primarily a visual experience for people. When we have plenty of light we find it easier to get around and see details of objects, and when it gets dark we know we should go to bed. For plants, on the other hand, light is much more important, since to a certain extent they use light as "food". In this regard, not only the quantity but also the quality of light is important for them.

As you know from school biology course, the basis of plant life - photosynthesis. As a consequence of this complex chemical process, water and carbon dioxide are converted into oxygen and sucrose with the help of light, and the green mass grows as a result. But in addition to the well-known photosynthesis, it is important to be aware of the existence of the photomorphogenesis phenomenon. In simple terms, under the influence of light rays of different spectra such processes as seed germination, root system growth, flowering and ripening of fruits are activated.

So when choosing a lamp for plant lighting, it is important to consider the spectral composition of the light emitted by the device and take into account some other indicators.

Basic characteristics of light fixtures

To find out what characteristics of the majority of bulbs for sale and to learn to read the markings on the packaging of light fixtures I invite you to take a small excursion into physics.

W (W) - watts, power of light fixtures

W (W) - watts, power - they indicate the amount of energy a light fixture consumes. It is important to understand that this indicator is not always directly proportional to the light output, because when converting energy into light beams some of it is lost.

Accordingly, there is a relationship between power and luminous intensity, and a fluorescent lamp with 40W indicator will look brighter and light a much larger area than a similar 15W luminaire. But nevertheless, this value is not all that simple.

If you compare the popular energy-saving lamps to other types of bulbs, for example, they will shine brighter than other lamps for the same number of watts, although they use less energy. So watts are more useful in calculating how much the meter will "wind up" in the end by regularly using the lamp.

Lm (Lm) - Lumens, amount of light

Lm (Lm) - Lumens are units for measuring light output, that is, they indicate how much light a lighting fixture gives. In simple terms, lumens indicate the brightness of light.

The requirements of plants regarding light intensity depend on their species. If you take the average values for indoor flowers the light amount should not be less than 6000 Lumen for a sure growth and development. But it is best when it is close to 10000-20000 Lumens. By the way, in the summer time on the surface of the soil, the illumination is from 27000 to 34000 Lumen.

K - Kelvin, shades of light

Kelvin - this unit shows the shades of light, the so-called light temperature. That is, how much the glow is visually perceived as warm or cool (not to be confused with the degree of physical heating of the lamp). Why does this indicator need a florist?

The fact is that scientists have revealed the relationship between light temperature and plant development, so it is very important that the flowers receive light of optimal "temperature".

G - cap

This characteristic will be important if you buy a fluorescent lamp and housing (lamp) for it separately. With bulbs, screwed into the socket, the base is designated by the letter E, with a standard socket marked as E40.

V - Volts, voltage

The voltage at which the lamp works; on some lamps indicated the limiting range of operation of the lamp. For example, 100-240 V.  Most domestic light fixtures operate from a standard 220 Volt power supply.

The right phytolamp - choosing a lighting device for additional lighting of plants
For plants, it is not only the amount of light, but also the quality. © Orchids Made Easy

Selecting a fluorescent light bulb to illuminate plants

According to studies, approximately 6500 Kelvin is required for seed germination, seedling growth and successful vegetation. And 2700 Kelvin for maximum blooming and fruit-bearing.

W arm White (WW), "natural white light" (Neutral White Light (NW) ) and "cool white light" (Cool White (CW) lamps are generally available for indoor lighting.

Depending on the manufacturer, the performance of these lamps may vary slightly. Typically, fluorescent lamps of warm white light have a characteristic in the range of 2700-3200 Kelvin, natural light - 3300-5000 K, cold white light - from 5100 to 6500 K. There can also be daylight labels (Day Light), whose values start at 6500 K.

In this regard we should also mention such a concept as nanometers (nm). Unlike Kelvin, nanometers indicate the wavelength of light radiation. The interval of electromagnetic radiation visible to the human eye has a wavelength in the range from 380 nm to 740 nm. Scientists have proven that the 660 nm (visible to the human eye as red light) and 455 nm (perceived as blue) are the most effective for the full development of plants.

This is because the energy required for photosynthesis is mainly provided by the red rays of the spectrum. The green and yellow component of the light is practically useless for the plants.

According to special instruments, the cold light bulbs have the most green and blue, and almost no red. Whereas a warm light bulb has a significant amount of red. So if you are planning to light your plants with normal household daylight bulbs (fluorescent bulbs), it is better to combine both types of fixtures. For example, warm white 2800 K and cool white or daylight 6500 K, because the first one has a lot of red, which is important for plants, and the second one has a considerable amount of blue.

The right phytolamp - choosing a lighting device for additional lighting of plants
The most effective for the full development of plants are 660 nm (human-visible as red light) and 455 nm (blue).

Phytolamp Osram Fluora

I want to separately mention a popular lamp for special purposes - phytolamp Osram Fluora ("Flora"), suitable both for winter lighting of potted flowers and for additional lighting of seedlings indoors. The spectral composition of this lamp is specially tailored to optimal plant growth and development with intensive light within the 440 and 670 nm spectrum.

Five different types of this phyto light can be found on sale:

  • 438mm - 15W - 400 Lumen;
  • 590mm -18W 550 Lumen;
  • 895mm - 30W - 1000 Lumen;
  • 1200mm - 36W - 1400 Lumen;
  • 1500mm - 58W - 2250 Lumen.

The declared service life of the illuminator is 13000 hours.

The advantages of "Osram Fluora" phytolamp :

  • phytolamp "Flora" is balanced in the spectrum, so it contributes to the full development of plants;
  • phytolamp emits light in the necessary range, and at the same time it does not consume energy for heating and light production in the "useless" part of the spectrum;
  • similar lights consume relatively little electricity;
  • the fluorescent bulb is virtually unheated and does not cause burns to plants;
  • a functioning light bulb has no visible flicker.

Disadvantages of "Osram Fluora" phyto-lighting :

  • unusual pinkish-purple color, which, according to some reports, negatively affects vision, and also has a negative impact on human well-being (causes apathy and some irritation), so it is recommended to shield this lamp from the main living space;
  • High price for the lighting device, several times higher than the cost of conventional household lamps;
  • like phytolamp can not always be found on sale;
  • Necessity to buy the body and cord with plug and switch, as well as self-assembly of the lamp, as these lamps are usually sold separately;
  • Lamps type "Osram Fluora" ignite poorly at low temperatures, so they cannot be used in unheated greenhouses;
  • Lamps "Osram Fluora" have less light output (brightness) than conventional "daylight" lamps;
  • this phytolamp also has a significant disadvantage that is common to all fluorescent tubes - the longer the lamp is in use, the less light it begins to emit (near the end of life, this figure can be about 54% of the original).
The right phytolamp - choosing a lighting device for additional lighting of plants
Growing plants under "Osram Fluora" phytolamp. © Ludmila Svetlitskaya

Rules of using fluorescent lamps for plant growing

When calculating the amount and power of lamps required for additional lighting we can use a standard formula: 1 m2of growing area will require 5500 Lumen. So a window sill or shelf with plants 1 meter long and about 50 centimeters wide would require 2,750 Lumens.

that is, according to this formula, using a Osram Fluora to light up this amount of seedlings would require three lamps at 895 cm/30 W-1000 Lumen. But in practice, for such an area usually not more than two lamps are used, and with sufficient light from the street you can do even with one lamp. Therefore, in this case you need to consider the individual conditions of each apartment and the degree of light requirements of specific crops.

The main signs of lack of light can be called: elongated stems (elongation of internodes), pale coloration of leaves, yellowing of the lower leaves. If this happens you can try to lower the lamp or add another light bulb.

As far as lighting for houseplants in the wintertime is concerned, the experience shows that for tropical houseplants (Monsters, Citrus, Philodendrons etc.) one T8 fluorescent lamp 60 cm long with 18 Watt at 25 cm above the flower is sufficient.

For tall palms up to two meters high two T8 fluorescent lamps with 36 Watt and 120 cm length are needed. It is very useful to use a screen of reflective materials.

When placing fluorescent lights, it is important to install them at a height of 15-20 centimeters. The maximum distance should not exceed 30 cm from the tops of the plants, because when you reduce it the light output becomes much less than stated (the height of 30 cm reduces the light output of the lamp by 30%). But too low (less than 10 centimeters) to hang the lamp is also not worth it in order not to burn the foliage. In addition, low placement reduces the light area.

The operating time of the lamp should be set on the basis of a full day of light. For most plants, the duration of illumination in late fall, winter and early spring should be 9-12 hours. For seedlings, the first time it is better to be in the light for about 16 hours. Lights should always be turned off at night. Round-the-clock illumination not only will not bring any benefit, but also will harm the plants.

The right phytolamp - choosing a lighting device for additional lighting of plants
To strengthen the brightness of the phytolamp, it is desirable to cover the walls of the rack with light-reflecting material. © Ludmila Svetlitskaya

Choice of LED (LED) lighting for plants

In this article we will not touch the ready-made LED lights developed by professionals for plant lighting. But if you decide to assemble an LED lamp yourself or use an LED strip, you will need some theoretical information.

The best LEDs for growing plants are red and blue. It is very important to choose the right wavelength: for reds it should be 660-670 nanometers (nm) and 440-450 nm for blues.

A separate issue is the ratio of red and blue LEDs. According to researchers and practicing gardeners, seedlings grow best when using blue and red LEDs in a ratio of 1:2. Similar proportions (from 1:2 to 1:4) promote active vegetation and will be beneficial not only for seedlings, but also for any plants that are growing green mass. In the flowering and ripening stage of fruit, a ratio of blue to red LEDs of 1:5 to 1:8 is recommended.

The optimum power of individual LEDs used to illuminate plants is 3-5 watts. One LED of this power is sufficient for an illumination area of 10-20 cm2. But on sale you can also find ready-made LED strips. However, they usually consist of diodes of small power, so it is advisable to use them in combination with fluorescent lamps.

The right phytolamp - choosing a lighting device for additional lighting of plants
Our homemade lamp for plant illumination. © Ludmila Svetlitskaya

Whether it is reasonable to make a phytolamp with your own hands?

I have to say right away that our attempt to build a LED phytolamp by ourselves ended in failure. Nevertheless, a negative experience can also be useful, so I will briefly tell you the story of our experiments.

Note: According to some reports the Chinese LEDs are usually of low quality and their characteristics do not match the manufacturer's claims.

For assembling the LED phytosensor we needed: 3 W LEDs (red and blue), a power driver with output power from 54 to 105 volts, aluminum plate, terminals for wires, wire with plug and switch, wooden rail, 5 meter wire, heat resistant adhesive.

I will not go into detail about how we, absolute humanitarians, short-circuited twice when trying to turn on the newly-built luminaire. I will only note that the finished lamp worked successfully for no more than two weeks, after which the LEDs began to burn one after another and needed constant replacement.

The reason was that during operation the diodes heated to a critical temperature, and for the successful operation of this type of bulb cooling (cooler) is recommended. An additional negative factor in our lamp was that the metal strips with LEDs were placed on a wooden frame, and wood does not provide a sufficient heat sink. Perhaps there were other mistakes, which are not easy to guess for humanitarians.

Course every situation is different, but I would not advise to assemble the lamp by yourself to people without technical education or with no experience in the field of electricity. In particular, in our situation the well-known principle worked: "a miser pays twice". The money was spent not only on the purchase of parts for assembling the failed version of the lamp and updating the regularly burning LEDs, but also on the subsequent purchase of ready-made lighting fixtures.

Currently we are lighting our seedlings with phytolamps "Osram Fluora" as well as with household daylight lamps in combination with LED strips.