Can you burn plants with LED grow lights? Even though LED lights are the safest for your plants, they can still hurt them and even burn their leaves if they're too close. LED lights can even cause photo-bleaching in plants that don't need plenty of light throughout the day.
This 100W LED light was just too close to the seedlings, causing them to get burned and turn purple and suffer, they can get burned just like we do in the bright sun! It is true that your seedlings need bright light to grow healthy and strong—but, too bright a LED light could actually damage them if it's too close!
And while using a grow light can be beneficial, they can also burn plants if they're used improperly or placed too close to them. In an attempt to use extra light to help a plant and keep it healthy, these examples can cause a great deal of harm instead.
If you are growing seedlings under two-bulb fluorescent fixtures, you can usually achieve a good color balance by combining one cool white and one warm white bulb. A set of stacked shelves with fluorescent T5 lamps (or LED lamps) makes it easier to grow a large number of seedlings.
Where Should Grow Lights Be Located? For seedlings, LED grow lights should generally be mounted between 24-36 inches above the plant canopy – however, this depends on the power (wattage) of the light source.
Vegetative Growth & Flowering
During the seedling phase, when plants are tender, lights are suspended higher. Generally, LED lights should be about 24-26 inches during this phase, and then lowered to 18 to 22 inches during the vegetative and flowering stages of growth.
Telltale Signs of Too Much Light
The most apparent sign is leaf burning. This typically causes the yellowing of leaves at the top of the plant but the veins stay green, and the leaves take on a yellow or brown, burnt look.
High Light Stress In Plants
If a plant is getting too much light and suffering from high light stress, its leaves may look as though they have burned or simply are falling off. In many cases, the soil will be dry to the touch, too.
Since sunlight is what plants naturally use to grow, the best color light for seedlings is the color that best mimics sunlight. The light from the sun includes all colors on the spectrum, so a full spectrum light is ideal.
' plants do require a daily respiration period of at least 6 hours per day (for seedlings) and ideally 8-10 hours for more mature plants. Therefore we do not recommend providing more than 14-16 hours per day of light, even if you are growing long-day-loving varieties and trying to induce flowering/fruit from them.
A: In general, you should not leave grow lights on 24/7. Plants need a light-dark cycle to develop properly. It's believed that they truly do “rest” during periods of darkness, and probably use this time to move nutrients into their extremities while taking a break from growing.
After the plants reach the final stage of grow, and get to their full size, we do not need to use the grow light that much. Even though they've already stopped growing, you shouldn't ditch the grow light completely. A fully-grown plant would still need about 12 to 14 hours of light per day.
Now, despite LED grow lights not generating lots of heat like HID's, their light spectrum can be overwhelming to lots of plant species if they're hung too close. When this happens your plants will suffer from light bleaching, which will impact how your plants take in sun and convert it into energy for growth.
They can last up to 100, 000 hours, which is much longer than other light sources. Next, unlike MH and HPS grow lights, dimming LED grow lights does not decrease the efficiency or change the light spectrum. Dimmable LED grow lights help you save energy because the current consumption is reduced when you dim the lights.
As an unofficial rule of thumb, many growers work on the basis that: You need 20-40 watts of power per square foot. Lower wattage LEDs of around 200 watts should sit between 12-20 inches from the top of the plant. Higher wattage LEDs of 1000 watts and above should sit between 36-46 inches from the top of the plant.
Yes LED lights can burn the leaves of the plants. High intensity LED lights can be too much for plants, especially when they are extremely close to the plants. Exposing plants for long periods to lights (as we have discussed) will also lead to leaf burn.
Light Intensity
Over time, this can deplete the plant's water reserves and leave insufficient water for vital processes such as photosynthesis. If the plant's capacity to dissipate heat is depleted, or if the amount of heat generated exceeds the plant's ability to dissipate it, the plant will suffer heat damage.
Vegetable seedlings and other “full sun” plants require about 2000 to 3000 lumens (at minimum) per square foot of growing space. So, if you're growing just a single standard tray of seedlings, using a grow light that emits 3000 lumens is sufficient. Otherwise, do the math and scale up to a brighter light.
How long to keep grow lights on plants depends on a number of factors. As a general rule of thumb, most vegetables and flowering plants need 12 to 16 hours of light per day, with flowering plants at the top end of that range. Plan on giving most plants at least 8 hours of darkness per day.
Seedlings should be watered once a day or every other day, depending on how much sun and heat they get. Remember that seedling roots are fairly close to the surface and they're growing in a small amount of media, so they don't need a deep soak the way larger plants do.
Attach them to a timer set to 12 hours of light per day. The seedlings will thrive, thinking it's later in the spring. That being said, plants do need some darkness to grow, so make sure the timer also turns the lights off.