9 Tips for Choosing The Right LED plant grow light for Seedlings
In our harsh climate, when it can snow in May, and the sun is an infrequent guest, the seedlings that many gardeners grow on windowsills may not survive until spring. A plant grow light will help maintain the strength of young plants in the cold season.
In this article, we will answer the question, why are LED plant grow lights so good compared to their predecessors – sodium and fluorescent lamps, and what is their advantage over modern energy-saving lighting devices.
Advantages of LED plant grow lights:
- energy savings,
- content in the light flux of spectra useful for plants, accelerating photosynthesis.
Decide on the shape of the plant grow light
If you have a window sill, a table, a long shelf, shelves, then, of course, it is more convenient to purchase a linear plant grow light. It will illuminate seedlings or flowers in a long row evenly. If the flowers are located on a radius stand, you need to highlight a miniature tree or a small area on the table, it is better to use a basement plant grow light.
Check the spectrum of diodes in the plant grow light
It is well known that plants need sunlight, which consists of different wavelengths and colors, for growth and development. In the spring, during the period of growing seedlings, when there is not enough sunlight, artificial lighting lamps are usually used to supplement the plants. However, their emission spectrum is limited and occurs mainly in the yellow and green color sectors. In addition, incandescent lamps consume a lot of electricity. Fluorescent and modern energy-saving lamps are more economical, but they emit little light in the red and orange spectral regions. And plants respond well by growing in response to blue and red colors.
This optimal combination of colors was achieved when using LEDs in plant grow lights . Therefore, these light sources are called bicolor. To choose the right lamp, you need to look at the so-called spectrogram (see Figure 1). It is also on the packaging of the lamp itself. The spectrogram should have peaks in the blue and red sectors of the spectrum. In the blue sector, the optimal wavelength for seedlings is 440-450 nm, and in the red sector – 650-660 nm. If the spectral indicators deviate greatly in both directions, such a lamp is not worth buying, since waves of a different length are ineffective for seedlings.
Distinguish between the real and nominal power of the diode
Diodes come in different wattage – 1 W, 3 W or 5 W. For the needs of the “home greenhouse” the most suitable are emitter lamps with a primary lens, which diffuse light at an angle of 120 degrees. A 3 W lamp with the correct ratio of emitted light and heat is considered optimal.
In order not to be mistaken with the choice of a lamp, it is necessary to distinguish between the concepts of nominal and real power. Let’s figure out what they mean. The rated power is the power at which the diode operates at its maximum limit. This means that the “life” of the diode under such a load will be short. To make the diodes last longer, they are “powered” by half of their power, that is, a 3 W diode will in reality “show” 1.5 W. This is its real power. Self-respecting manufacturers of LED lamps are required to indicate this information on their websites.
Correctly calculate the power of the LEDs in the lamp
How to calculate the total power of LEDs? How many diodes should there be in a lamp? The answer to these questions depends on your specific situation. The most important thing in the choice is the ratio between the diode and the radiator (more on this in point 6).
The formula for calculating the number of diodes is quite simple: M = K × M1 , where M is the total lamp power (W), K is the number of diodes, and M1 is the power of one diode. However, not all manufacturers are extremely honest with their customers. To avoid falling for the bait, we close the knowledge gap.
Let’s say you chose a 54W lamp with 18 diodes from Aliexpress, where the manufacturer claims that the power of each diode is 3W. If you measure it with a wattmeter (a device for measuring the power of connected devices), then it turns out that it produces 11 watts.
It must be borne in mind that the diode cannot work at maximum for a long time! So, let’s count: we divide 54 W by 18 diodes, we get 3 W for each diode, which work at full! But this cannot be! However, you pay for 54 watts of nominal power and 27 watts of real power (see information above.) But in fact, it gives out 11.6 watts. That’s far from 27 watts.
The actual output of the diode is half the power. Then if we take 1.5 W of the power of each diode and multiply by 18 diodes, then we get that this lamp should consist of at least 27 diodes, and not 18, as it is in fact. Cheating? No, it’s just that there are diodes of lower power, that is, with a power of 1 W, which operate at half of their power. Manufacturers, of course, do not write about this.
But how did it come about? We take 11.6 watts of real power from the outlet, divide by 18 diodes. And we get 0.64 W! That is, 0.64 W is just about half of 1 W.
Consider the radiator area
The radiator is an aluminum housing, which is located in a circle in the basement lamps or, if it is a linear lamp, the entire housing is the radiator. In Figure 3, the radiator is indicated by arrows.
The radiator is designed to dissipate the heat generated by the diodes. Therefore, the volume of the radiator must be calculated for the number of diodes so that they do not overheat. The maximum temperature on the crystal of the diodes should not exceed 70-75 ° C, otherwise they “degrade”. That is, if there are many diodes in the lamp, and the radiator is small, such a lamp will quickly fail.
In order for the LED plant grow light to work properly, the ratio between the radiator area and the number of diodes must be well verified. The distance between the diodes is equally important, that is, if there is enough space between the diodes, the heat is distributed faster.
Consider the distance from the lamp to the illumination area
At what distance from plants should plant grow lights be placed? The answer to this question will depend on which room and how many plants you plan to grow, as well as the length of daylight hours.
In order for the lamp to retain its functions, and the effect of such illumination does not diminish, it can be equipped with additional lenses in order to narrow the light beam. The flare area will depend on the lens chosen. In order not to overpay for extra lamps and unnecessary power, it is better to pick them up with the help of professionals.
Consider installing additional lenses
As mentioned earlier, diodes already have a primary lens and a 120 degree exposure angle. But if you hang the lamp too high, less light will reach the plants, and it will be scattered more. That is, the light will cover the area that is not useful. Such use is ineffective, but you will have to pay extra for electricity. Installing additional lenses will help solve this problem. They are 15, 30, 45, 60, 90 degrees. Fitting a lens will allow you to select the desired height and maintain the useful lamp power required by the plants.
Select the lamp of the desired spectrum
Bicolor (bicolor spectrum) – the main spectrum for giving the plant the energy needed for photosynthesis.
A lamp with this spectrum is recommended:
- for highlighting any plants on a windowsill, balcony and in places with a minimum amount of sunlight;
- for growing seedlings and young plants;
- for supplementary illumination of adult plants in a room with additional light sources;
- to support plants in winter and in low light conditions.
Full spectrum . These are bicolor lamps with a wider range of peaks in the red and blue field. They are versatile and will suit many plants. In terms of energy efficiency and spectrum peaks, these light sources are slightly inferior to bicolor lamps, but due to the wider spectral zone, they allow the plant to give the plant a maximum of artificial light, similar in effect to the sun.
The multicolor spectrum is a unique lamp that combines red, blue, warm white and far red light. It provides maximum stimulation of flowering and fruiting in many plants, including orchids and adeniums, as well as a large proportion of red and blue light for photosynthesis during the growth stage. A lamp with this spectrum is recommended:
- for illumination of adult plants;
- to stimulate flowering and fruiting;
- for growing indoors in the absence of sunlight;
- for supplementary lighting of indoor flowers, especially orchids;
- for illumination of decorative leafy plants.
Peppers, tomatoes, eggplants, cucumbers are recommended to light up from 8 to 13 hours a day. Green crops (salads) – 8-11 hours a day, tugovid plants (celery, radishes, turnips) – 12-16 hours a day.
Buy LED plant grow lights with a guarantee
This is a very important point. Manufacturing companies and bona fide sellers must issue a warranty on the lamp. It is very important. By buying a lamp from an unverified seller, you will not be able to prove to him that it failed through no fault of yours, but, for example, due to a power surge. And not everywhere will undertake to repair such a lamp. Therefore, choose LED plant grow lights with a minimum of 1 year warranty.