Today, more and more growers are getting rid of traditional HID and fluorescent T5 grow light and installing LED grow light. The heat emitted by LED is less than that of HID light source, which means that the distance between the 600 watt grow light and the crown is different from that of the traditional 600 watt grow light. It is also important to understand how the optimal growth light distance affects the different stages of plant growth.

This article summarizes the different lighting needs of various plants (including hemp) according to their growth stages. It also describes how to determine the appropriate distance between LED lighting and plant canopy to nourish plant growth, and the importance of PPFD (PAR) and other popular growth lamp terms.

How to Measure the Light of Plants?

PAR (photosynthetically active radiation) describes the part of the visible spectrum (400nm-700nm) that plants “see” and use for photosynthesis. PPFD (photosynthetic photon flux density) measures the amount of light (PAR) received by plants over time. PPFD is the optical density received by plants over time, measured in micromolars per second per square meter.

One way to visualize PPFD is to imagine the sun “pouring” light onto plant leaves. When the sun shines light on plants, their leaves are collecting energy. PPFD is a measure of the amount of light (photons) that the sun “pours” on plants over time. PPFD is an important indicator because it can help growers accurately measure the light intensity of canopy photosynthesis. It’s also important because lights that are too close to the canopy can cause burning, bleaching, stunting or discoloration.

Distance Chart of 600 Watt Grow Light

The distance chart shows the performance of the 600W LED grow light at different distances from the plant canopy. It outlines light intensity (Lux) and provides PPFD. The “light footprint” or canopy coverage is also shown. The intensity, PPFD / par and “light footprint” all changed with the increase or decrease of light distance from plant canopy.

The chart also highlights how changing the distance of the same 600 Watt LED light changes light intensity and “light footprint” or canopy coverage received by plants. When the light source is close to the crown, the light intensity increases. Generally speaking, growth lights should be installed at the plant growth stage closer to the plant canopy and higher (far away) from the plant canopy during the flowering stage.

How far should LED grow light be from plants?

Because LED grow lights hardly generate heat, many gardeners think they can put the lamp directly above the plant canopy. However, this is not the case. The light from an LED may look dark and feel as if it doesn’t emit heat, but it can still burn plants. If you start to see the Yellow / bleached color on the leaves, you will know that the growth lamp is too close.

How close should HPS and metal halide grow lights be to the top of plants?

Using traditional HPS and MH grow lights, it is easy to see if the lights are too close to your plants. Just put your hands on the top of the plant for 30 seconds. If the heat starts to make you feel uncomfortable, it means that the growth lamp is too close.

Where should the 600 watt grow light be placed?

For seedlings, LED grow light should normally be installed between 24-36 inches above the plant canopy, however, depending on the power of the light source (Watts). Place the LED grow light farthest from the seedlings (~ 36 “) – this will maintain low levels of heat and light intensity and help prevent the seedlings from drying out. Once rooted and germinated, the lamp can be moved closer (usually within the first 2-3 weeks).

In plant growth stage, the LED growth light should be 12-24 inches from the top of the crown. At this stage, photosynthesis needs more light, so the light source should be close to the plant.

As plants enter the flowering stage, their need for strong light decreases. The top leaves of the canopy should be 18-24 inches from the light source to produce flowers. It is at this stage that the height of the plant increases and the fruit is produced. Depending on the light and the way you want the crop to grow, there is no need to change the height of the light during flowering, especially if you don’t want higher plants.

How Far Should 600 Watt Grow Light Be From Seedlings?

In the early stage of growth, seedlings are very fragile and the required light intensity is low. This means you don’t want to increase intensity too early, because the seedlings thrive in a more gentle way. According to the size of the lamp, it is safe to place the growth lamp between 24-36 inches from the top of the soil.

How Far Is LED 600 watt grow light from Flowering Plants?

As plants grow, their needs change. Once the vegetative stage is completed, the plant will enter the flowering or “flowering” stage. For mature plants, they already thrive where they need to. In the flowering stage, the LED plant growth lamp should be located 16-36 inches away from the plant canopy. The growth of light will increase the intensity of light, thus maximizing photosynthesis. However, if growth lamps are too close to plants, they will lead to wider and more widespread growth and may even damage plants.

What about other growth stages（ H2)

According to each stage of growth, plants need different degrees of light. In order to know exactly how far the 600 watt grow light should be from the plant, it is important to consider the different growth stages (2). It is also important to consider the power output of the growth lamp, which is usually related to the wattage of the light source, which is the main factor to determine the optimum distance of LED when starting the growth process.

The growth of plants can be divided into three different stages: seedling stage, vegetative stage and flowering stage. This means that once healthy roots are firmly established, it’s time to increase intensity and reduce lighting.

Seedling Stage

At the initial stage of seedling growth, grow lights should be placed in the higher position of plants to avoid soil drying.

Some growers may want to irradiate the seedlings with high-intensity light to promote faster growth, but it won’t help until the plants mature. Seedlings are too fragile at this early stage and need a more gentle approach. Once the plant matures, higher light intensity is needed to promote photosynthesis.

Vegetative Stage

During the vegetative stage, plants respond well to strong light – that’s when they are maturing and growing rapidly using photosynthesis. In order to increase light intensity, LED grow lamps should be close to plant canopy. Strong and healthy stems and roots are the key to successful and repeatable yield.

Although increasing the light intensity will promote the growth of the vegetative stage, it is important to closely monitor the plants to ensure attention is paid to the adverse symptoms caused by excessive or insufficient light.

Flowering period

Flowering is the last stage of the plant growth cycle during which fruit production and stem growth accelerate. With the transition of plant growth from vegetative growth stage to flowering or flowering stage, “staged” is a good way. To this end, gradually increase the height of the LED plant light away from the plant canopy (using the height recommendations outlined above). Closely monitor the distance, keeping in mind the plant height and flowering requirements for a particular plant / crop.

The Adverse Effects of Too Much Light

When plants like marijuana receive too much light at any stage, they usually show symptoms of pain. Since LEDs don’t emit too much heat, the main problem that needs to be monitored closely is any sign of “light burning.”. Other side effects associated with the growth of plants that are too close to the plant canopy may be discoloration or dysplasia / irregular growth. These two must be identified quickly and the height of the growth lamp should be adjusted accordingly.

Signs of mild burning of cannabis plants include upward leaves and so-called “bleaching.”. Bleaching is the white or yellow color on the leaves closest to the light. Light burns can also be identified when the veins of the plant are green and the rest turn yellow.

Different Light Distance — Cannabis and Other Indoor Plants

As growers transfer crop production to indoor areas, the use of LED grow lights for cannabis production is becoming more and more popular. LEDs also benefit growers because they can use specific spectra to provide more targeted lighting conditions for different crops. Compared with traditional light sources, other benefits of considering LED plant growth lamps include lower power consumption, less forward heat and increased production in a shorter time.

The LED grow light distance should reflect the height and evenness of the plant required by the grower, as well as good leaves and healthy flowers. If we look at the crop demand for salad vegetables or lettuce compared with marijuana, we will find that salad vegetables and lettuce are suitable for short and wide growth, while marijuana is more suitable for higher and narrower growth.

Regardless of your crop type, farmers and cannabis growers want the highest quality yields in a shorter growth cycle.

Lighting Distance of Traditional 600 Watt Grow Light

Traditional high intensity discharge lamps (HID), such as high pressure sodium lamps (HPS), metal halides, and fluorescent lamps, were widely used before led became popular for indoor planting applications. Historically, the initial cost of these lamps is much lower than that of LED growth lamps. Therefore, they are more affordable and therefore can be used by large indoor growers.

The distance between HID or fluorescent plant growth lamp and plant canopy should be larger than that of LED. This is partly because they emit more forward heat than LEDs, but they also have only a few different wattage / light outputs. The installation distance of growth lamps varies with each stage of growth and depends on the number of tiles used.

Although the initial cost of traditional plant growth lamps is low (lower cost), they need more maintenance over time, requiring frequent replacement and / or cleaning of lamps, and they have great limitations in lighting control – many will not darken and may take a long time to turn on all optical output.

Fluorescent 600 Watt Grow Light

Fluorescent grow lights are divided into three (3) basic types – T5, T12 and compact fluorescent lamps. In order to get different light intensity, growers must adjust the height of the lamp from the plant canopy accordingly. One advantage of fluorescent lamps is that they are difficult to cause light burns because they don’t emit enough heat. In any case, light intensity and heat should always be closely monitored.

For young crops, about 6-12 inches is a reasonable height because they need more intense light. When they go from vegetative growth to flowering, it’s wise to double that distance to about 12-16 inches. As a general rule, when using t5s, it’s wise to keep them as close as possible, but monitor for overheating or drying.

HID 600 Watt Grow Light (metal halides and high pressure sodium – HPS)

Metal halide (MH) lamps provide a lot of blue light, which is considered to be the most suitable spectrum for plant growth stage (3). High pressure sodium (HPS) lamp is an ideal choice for plant growth and flowering. Both generate much more heat than LEDs, but are relatively cheap to buy.

One way to test hid heat is with the back of your hand. This can help you measure the correct growth light distance. Just place your hand on the top of the roof and hold for 30 seconds. Your hands should get hot, but not unbearable. If this happens, increase the growing light distance above the plant.

Many commercial growers use 1000W HID lighting, usually starting at a height of 19-26 inches. From here, they can get closer.However, because hid generates a lot of heat, it is important to avoid heat burns, which can damage any plant. In addition, indoor ventilation of HID lamps is very important because they emit more heat.

With 10 years of collective experience and expertise, Bbier lighting is the leader in led grow lights solutions, and continues to innovate and drive the industry forward. Bbier lighting biological priority and research based LED plant growth lamp method is led by nature, because we have constructed a bright full spectrum LED, so plants grow stronger and yield higher from seedling to maturity.

Compared with HPS, our foldable LED grow lights 400w-1600w can reduce power consumption by 50%, reduce the heat generated by up to 50%, and provide natural light for your plant for ten years. Our 600 watt grow light provides an optimized spectrum for excellent results while using plug and play configurations. Our 600 watt grow lights are easy to install and maintain effortlessly, thanks to our continued commitment to support partner LED integration.