What to Know When Switch from HPS to LED
Many growers would like to switch from traditional HPS lights to LED grow lights aiming to reduce energy cost, increase efficiency, and get higher yields. It goes without saying that LED grow lights provide many advantaged over HPS lights. However, there are many differences between HPS and LED grow lights, such as the heat, spectrum, intensity, energy consumption, etc. These differences may also affect the growing environment and settings of relevant equipment. For commercial growers, the cost of HPS to LED transition can be tremendous. To achieve a good ROI and a successful transition, there are several things growers should know before starting switching from HPS to LED.
Consider effects of spectrum on plants
LED grow lights can produce HPS spectrums and more. Therefore, you should consider the effects of spectrum on plants when switching from HPS to LEDs. The spectrum of HPS lights is re-dominant, which makes it ideal for flowering. The red-dominant spectrum helps plants grow taller and develop thinner stems. However, the spectrums of HPS lights can be modified because the gases in lamps decide their color. In contrast, LED grow lights can mimic sunlight. In addition, LEDs can be customized with the light spectrum that precisely meet crops needs. LEDs are rich in blue, red, green, and yellow light. With the balance spectrum, plants are more likely to grow thrive. Since the spectrum affects the photosynthetic responses of plants, consider the difference of spectrum between HPS and LED before a transition from HPS to LED grow lights.
Adjust the temperature
As known, HPS lights produce more than LED grow lights. The significant amount of heat will warm up the upper leaves of the plants, so as the temperature in grow rooms. The leaf surface temperature is critical because leaf is the place where photosynthetic reactions take place. Excessive heat or too cold temperature will slow the photosynthesis or even damage the plants. But in a certain temperature range, warm leaf surface temperature can promote transpiration and accelerate the movement of water and nutrients. LEDs produce little or no radiant heat. So LED grow lights can be placed closer to plants. However, due to the difference of heat, a grow rooms fitted with LED grow lights should have a higher temperature than with HPS lights to get the similar performance. Thus, you may need to adjust the temperature when switching from HPS to LEDs.
Consider the lights intensity
As mentioned earlier, HPS lights can produce a large amount of radiant heat while LEDs only create little or no radiant heat. As a result, HPS lights cannot be placed too close to plants. But the higher mounting height of HPS lights limits the light intensity that plant receive. When you place LED grow lights at the same height to HPS, you had better consider the difference of light intensity. Generally, LED grow lights have a higher light intensity than HPS at the same height. The higher light intensity is possible to damage your plants. Thus, growers should take light intensity into account when transitioning from HPS to LEDs. A PAR meter is helpful for checking the PPFD level in a grow room.
Regulate the water use
The radiant heat generated by HPS lights can promote transpiration, making the water move quicker from roots to next growing point. The addition of cooling machines like fans and air conditioners contribute to higher rates of transpiration. The increasing transpiration results the higher water usage. Growers need to water the plants frequently to ensure sufficient water for plant growth when using HPS lights. When you switch to LED grow lights, you don’t need to water the plants as frequently as growing with HPS lights. That is because the LED plant light produce less heat and slow the transpiration. As a result, growers should regulate the water use when switching to LED lights.
Wattage does not indicates the photons
It is a common misconception to compare the wattage to the photons received by the plant. Actually, wattage refers to the amount of electricity a grow light consumers. Selecting LED grow lights that have the same wattage with existing HPS light for a transition makes no sense. In stead, you should use the LED grow lights with the same PPFD to replace the HPS lights. PPFD means the Photosynthetic Photon Flux. It is used to measure how many photosynthetically active photons (400-700nm) that emit from light source per second. If you want to figure out the PPFD of HPS lights, turn on your HPS lights first. Then, let HPS lights completely warm up. Next, place the probe of the light meter in the middles of the growing area. The light meter should be placed as high as the top of the plants. At last, record the readings on the light meter.
You may need additional infrastructure
One of the most complex problems of switching from HPS to LEDs is the requirement of additional infrastructure. Wiring, track, or truss may be needed for a transition. So, if there is a simple 1:1 replacement from HPS to LEDs? The answer is Yes. For example, a 800W Horti-Top can replace a 1000W HPS lights one-to-one. But the reality can be more complicated. That is because HPS lights have reflectors to create a wide and diffused lighting distribution over the plants. LED grow lights do not have reflectors, so they create directional lighting distribution. The lack of reflector increases the required larger quantity of LED fixtures to ensure uniformity over the plants. Another problem is that different mounting height and layout of LED grow lights will affect the PPFD and light uniformity. You had better consult a professional horticultural lighting company for a customized light plan. The light plan can provide the optimal layout of LED fixtures and the highest uniformity for your grow rooms including greenhouses, grow tents, vertical farms, etc.
It seems that switching from HPS to LEDs is difficult and complex.
Don’t panic. Just contact us if you need any help. We will provide professional light plan and customized lighting solution for you.
