How Long To Use A Grow Light For Houseplants

Grow lights should be left on for at least 8 to 10 hours per day to simulate the duration of exposure to natural sunlight that plants generally receive in a day. Automating this procedure by setting your grow lights on timers will prevent you from forgetting to turn them on or off. Light timers are available online and at most big-box retailers.

How long should indoor plants have grow lights on?

A grow light’s optimal on time truly depends on a few variables. They consist of the specific light you’re utilizing, the surroundings your plant is in, and the purpose for which you’re employing the light (eg, foliage growth, vegetables or flowering).

You should be given precise instructions for using the light. But here are some general pointers.

  • Grow lights should be on for at least 8 to 10 hours each day in order to be successful. Depending on the situation, this can change from one to sixteen hours. It is better to choose an energy-efficient type when they need to be left on all day, which is why LED grow lights are so well-liked.
  • A grow lamp should always be placed above the plant. It imitates sunlight. The greatest option is always to place plants above a light source since they will gravitate there naturally.
  • Check to see if your grow light is touching or getting too close to plants if it starts to heat up.
  • Young plants or those that prefer the shade can survive with weaker grow lights, however larger plants and those with enormous leaves that can soak up a lot of light (like fiddle leaf figs) can benefit greatly from a stronger light.

Short vs Long Day PlantsHow Their Light Needs Differ

Scientists categorize plants as having “long” or “short” days in the context of plants.

  • In order to flower, LONG-DAY plants require brief periods of darkness. Basil, cilantro, parsley, dill, mint, and tomatoes are typical examples of LONG day plants.
  • In contrast, SHORT DAY plants require extended periods of darkness in order to flower. Avocado, mustard greens, marigolds, zinnias, and strawberries are typical examples of SHORT day plants.

Theoretically, all you’d need to do to replicate a plant’s optimum growing environment is to find out how long its ideal day is and use that information to set the grow light’s on/off timer.

The issue with this strategy is that it will probably cause your plants to blossom prematurely. Flowering is the beginning of the end for certain plants, such as lettuce and cilantro, but it’s a wonderful thing for others, like tomatoes and peppers, as the flower is what finally yields fruit. In addition to changing shape, leaves may also start to taste bitter at this time, and the majority of gardeners will pick them out and start over.

In addition to categorizing plants as having short or long days, we can also group them according to whether or not blossoming is preferred.

Using Light Duration To Promote (or Avoid) Flowering

You should therefore provide your plants with their appropriate light duration for plants where the blossom is desired. For plants, you should do the opposite if flowering is not desired. At this stage, we believe it is useful to divide the plant kingdom into four sections.

Give us a long day; we want flowers.

  • Fig
  • Peach
  • Tomato

Since we want flowers, please give us a brief day:

  • Avocado
  • Chamomile
  • Coffee
  • Cosmos
  • Marigold
  • Strawberry
  • Zinnia

Give a brief day to prevent flowering:

  • Arugula
  • Basil
  • Cilantro
  • Dill
  • Citrus balm
  • Lettuce
  • Mint
  • Parsley

To prevent blossoming, give people a lengthy day:

  • Ginger
  • Sage

Is There A Limit To How Long You Can Leave Lights On For?

In a word, yeah. Even plants with lengthy days, when blossoming is preferred, do have their limitations. We discussed this in “Plants Do Math At Night.” Plants do require a daily period of respiration of at least 6 hours per day (for seedlings) and ideally 8-10 hours per day (for more established plants). Therefore, even if you are cultivating long-day-loving types and trying to encourage flowering/fruit from them, we do not recommend supplying more than 14–16 hours of light every day.

How long should plants be exposed to artificial light?

It can be challenging to provide plants the right amount of light while they are being grown inside in order to keep them happy and healthy. Winter has arrived, which further reduces the quantity of natural sunlight accessible because the days are shorter and the nights are longer. At this time of year, the sun’s strength is also lessened. Artificial lighting should be used to augment or replace natural sunshine in order to cultivate healthy, beautiful houseplants and to maintain the bloom of blooming plants throughout the winter.

The light that a plant is exposed to must closely resemble sunshine for healthy growth. All of the hues in the spectrum are present in sunlight, and each is essential for the process of photosynthesis. Two of the most essential hues for the growth of plants are red and blue. Red encourages vegetative growth and flowering, but too much of it will make a plant lanky and strained. A fuller, stockier plant results from blue’s control of plant growth. Select a full-spectrum fluorescent gro-bulb for the best effects. For the healthiest and most vibrant houseplants, this lighting option is ideal.

Varying plant species require different levels of light. While some plants like dim lighting, others need intense light. The wattage of the lightbulb and the distance between the light source and the plant dictate the amount of light that is produced by artificial lighting. Knowing which plants to gather together beneath the fixture and where to position a light will tremendously aid you when choosing where to do so. Plants produced primarily for their leaves typically need less light than those grown for fruit and flowers, as a general rule of thumb. Plants exposed to artificial light should be rotated every week because the light from tube-style bulbs is stronger in the middle than at the ends. To enhance the quantity of light available to your plants, use white trays, mirrors, or trays lined with foil.

The majority of houseplants thrive with 12–16 hours a day of artificial fluorescent light. A plant will grow tall and spindly if it receives insufficient light, and it will wilt, lose color, have overly dry soil, and burn its leaf if it receives too much light. Each day, plants too need to take a break. Your plants’ development rate will be slowed down by an 8–12 hour period of darkness each day, which will also provide them the rest they need to form flower buds. For instance, the Christmas cactus requires six weeks of uninterrupted darkness—13 hours each day—to set bloom buds. The Christmas cactus won’t flower if it doesn’t get the necessary amount of downtime. To control the length of time your indoor plants are exposed to light and darkness, use an automatic timer.

The ability of the fixture to be adjusted is crucial when picking a plant light fixture. The fixture should be movable up and down to accommodate the various plant species’ differing needs for light intensity and growth height. You will be limited in the kinds of plants you can grow and how much you can use the fixture if it is not adjustable. Both adjustable shop lights and tabletop light fixtures are suitable for illuminating indoor plants. The size of the fixture is another factor. The amount of plants you intend to grow below the light should guide your size selection. Plants can be grown on multiple levels of lighting shelves that are provided by illuminated plant carts. While tabletop fixtures are lightweight and may be moved to new locations when needed, carts have wheels that make them portable.

Starting to use artificial light sources may seem scary, but you’ll be astonished at the impact it will make to all of your indoor plants, both houseplants and seedlings.

Is it acceptable to leave a grow light on continuously?

A: My plants will develop more quickly if I give them light all day, am I right? I believe that all I need to do is leave the lights on for them to transform into monsters!

A: Generally speaking, grow lights shouldn’t be left on all the time. For optimum growth, plants require a cycle of light and darkness. They supposedly do “rest during periods of darkness, and possibly utilise this time to transfer nutrients into their extremities while taking a break from growth,” according to theory.

Knowing that basic truth, keep in mind that most plants require at least 12 hours of light each day, of varied intensities. Your hydroponic plants’ precise requirements for sunshine as they develop and bloom can be found in your plant manuals.

Of course, you can place the lights over your hydroponic garden on a timer to ensure that your plants always receive the proper quantity of light. You never have to stress about forgetting to switch things on or off when you have a timer.

Is it okay to relax next to a grow light?

Discussions about the potential health effects to people have also been sparked by the rapid expansion of LED technology in horticulture lighting applications. This is partially caused by how differently the light in these applications appears visually (in terms of color and intensity).

Any sort of light, from any source, has the ability to cause damage to the eyes or skin at high enough intensities by sustained thermal exposure or photochemical effects of ultraviolet, blue, and/or infrared emissions. Blue light with shorter wavelengths and higher energy (400 and 500 nm) can harm the retina due to photochemical reaction and high intensity. Light sources with a higher concentration will provide more direct energy and pose a greater risk. For instance, gazing at a bright blue sky (scattered blue light) carries little risk, yet staring straight at the sun can nearly immediately cause irreparable harm.

Always avoid staring directly at intense light sources for long periods of time, especially up close. In reality, no one deliberately looks straight at a bright light source for very long. Common sense dictates that prolonged direct eye exposure to a potentially harmful light source will be avoided, and the human innate aversion reflex (we instinctively close our eyes or turn away) further supports this.

According to EN 62471, the standard for the photobiological safety of lamps and lamp systems, LED grow lights must also be evaluated for photobiological safety. This also includes 200 nm to 3000 nm spectral analysis of thermal and blue light. The EN 62471 exposure limit categories reflect the circumstances in which it is thought that the majority of persons could be exposed repeatedly without suffering negative health consequences. The rating simply identifies possible risk, it should be highlighted. Depending on use, the risk could not even materialize as a danger.

Since the eye is a complicated organ, it naturally strives to adjust to different lighting situations, therefore LED grow light spectra may not always appear as expected “natural for people. Changes in lighting conditions for the human eye, such as moving from an LED-lit growth environment to natural daylight, may momentarily impair color vision as the eye adjusts. This is normal, thus it shouldn’t be construed as being a possibility “injury brought on by LED light exposure.

In conclusion, it can be claimed that when designed, installed, and used in compliance with the relevant standards, regulations, and manufacturer’s instructions, commercially available LED light sources (for horticultural or other purposes) can be regarded human safe. Overall, LED grow lights are comparable to other lighting technologies in terms of photobiological safety.

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The biologists and engineers at Valoya write the blog entries. All of the content is unique and intended to aid in the better knowledge of LED grow light technology by researchers and growers.

Where ought grow lights to be placed?

* Depending on the grow light being utilized, coverage will change. Here, an LED source is used without a reflector to direct the light.

Table 1 displays the performance of a 600W LED grow light at different distances from the plant canopy. It provides PPFD (mol/m-2/s-1 or micromoles per square meter per second), describes light intensity (lux), and also displays the “light footprint or canopy coverage.” The distance between the light source and the plant canopy has an impact on the intensity, PPFD/ PAR, and “light footprint.”

Table 1 also shows how shifting the location of a 600 watt LED light affects the amount of light a plant receives and its “canopy coverage.” The light intensity rises as the light source gets closer to the canopy. Grow lights should typically be installed higher up (far away from) the plant canopy during the vegetative stages of growth and lower down (closer to) the plant canopy during the flowering phases of growth.

Can plants be burnt by LED grow lights?

Light won’t likely burn your plants, not even bright light. Although it won’t technically burn a plant, too much light might challenge your crops and have the opposite effect.

When ought my grow lights to be turned on?

It takes some practice to become an expert grow light user for seedlings. I’ll thus provide you with advice below on when to begin and stop using them as well as how far to hang them from the seedlings.

When Do I Put My Seedlings Under Light?

This one has a straightforward solution. As soon as the first seed begins to sprout, you should turn on your grow lights (or place your seedlings under lights).

Many different kinds of seedlings develop quickly, and as soon as they emerge, they start reaching for the light. So start off by giving them a lot of it.

How Far Should Seedlings Be From A Grow Light?

The seedlings and the grow light shouldn’t be too far apart. It’s recommended to always maintain it 1-2 inches above the tops of the leaves.

The plastic cover of the tray will initially hang immediately above (but never touch!) your fixture.

You will need to regularly adjust the lights to ensure that they are always directly over the top after your starts get higher and you remove the lid.

However, the leaves must never touch the bulbs since they could ignite. Therefore, be sure to check on them daily and adjust the light as needed. This task will be significantly simplified if you use an adjustable hanger!

If you see some seedlings at the edges are reaching or aren’t developing as quickly as those beneath the light, rotate the trays every day.

When To Stop Using Lights On Seedlings

When your seedlings are outdoors is the only time you should turn off the lights. They ought to be in the light as long as they are within the house.

You can turn off the lights when your seedlings are outside throughout the day once you’ve started the hardening process. However, you shouldn’t entirely stop using them until you’ve permanently relocated the seedlings outside.

Just be sure to always place them under the lights when you bring them inside, or else they’ll start to go leggy very quickly.