If you are growing plants or crops indoors, grow lights can be used to fulfill light requirements, but can also be dangerous if you overexpose them to light.
Consequently, once your grow lights are already set up, you need to know how long to keep them on plants.
If you are growing plants indoors, you always need to make sure that they get enough light for them to grow well.
The same is true for overexposing your plants to light. Although it can be challenging to determine the optimal length of time your grow lights should remain on, it can be determined with sufficient research and understanding.
Whether you are brand new to indoor gardening or already have experience, this page can be very helpful!
You’ll learn what you need to know about lighting to maintain the good health of your seeds, gardening inside, and houseplants.
When it comes to growing plants and crops, why is light vital?
Photosynthesis – which occurs when plants are exposed to light, carbon dioxide and water – is essential for your plant’s growth.
It doesn’t really matter whether the plants receive sunlight or artificial light.
Photosynthesis is the process by which plants produce glucose from carbon dioxide, water, and light. Glucose is what gives plants their energy.
Photosynthesis is essentially necessary for plants to create their own food. Therefore, they would grow healthy and avoid getting wilted.
You need light, but also need to know for how long you should place your plants under it.
Grow lights during the day: How long do you need to leave them on?
Let’s answer your other question about how long you should actually keep your grow lights on when growing plants indoors: Why does it matter whether plants receive natural light or artificial light?
It depends on what types of plants you’re trying to grow. Some require only a few hours of light, while others can survive 24/7.
However, you need to keep in mind that if you’re using artificial lights or grow lights, the plants you’re trying to grow will need greater light exposure than if you’re using natural light or sunlight.
What is the best way to keep my seedlings in lights?
Some people think it is okay to use the grow lights for 24 hours when they are seedlings or are just starting out and trying to germinate seeds. This is not true. In fact, some seeds would struggle to germinate if exposed to the sun.
Dark time is necessary for plants, and it still has something to do with photosynthesis.
During the period when the lights are off, the plants consume the glucose they produce when they are made of light, carbon dioxide, and water.
This process is known as respiration, and it allows them to grow healthy.
Does a 24-hour light cycle promote faster plant growth?
Some plants would require at least 12-16 hours of light exposure before respiration can take place. Most plants need darkness for at least 8 hours before respiration can occur.
Make certain you do your research when it comes to the needs of the plants you intend to grow.
The plants you grow in vegetative state do not really require a break from light exposure, so you can leave your grow lights on for 24 hours without worrying.
Here are some examples of plants that do well with full-day light exposure:
While it’s fine to expose these plants to light for 24 hours, we still suggest that you give them a few hours of darkness. This way, you’ll be able to spend less money on electricity for your grow lights.
Keep in mind that plants that exhibit fruit or flower need time away from light or darkness in order to achieve full flowering.
Typically, plants that prefer darkness should only be exposed to light for 12 hours. If your grow space, tent or box is enclosed and does not have any windows, then you must turn off your lights for about 12 hours.
This list of plants and crops that need dark time may serve as a guide for you:
- Spider Plants
- Creeping Fig
- Maidenhair Fern
- Parlor Palm
There are a few plants that require some darkness. Keep in mind that during the hours that your grow lights are off, there shouldn’t be any interruptions of light.
In addition, you will need to establish a routine for turning off your grow lights to avoid confusing your plants.
Tips to Make Sure You Don’t Overexpose Your Crops To Light
You need a plan when it comes to establishing a routine for exposing your plants or crops to light.
Alternatively, if you don’t mind spending extra money, you can use a light timer that you can integrate into your grow light system.
This means that you can set a timer to automatically turn on and off your grow lights. This video shows how to set up an analog grow light timer.
It’s helpful to know whether the plants you choose to grow need low, medium, or high light. Low-light plants only need four hours of light, while medium-light plants need six hours.
Some high-light plants require 14-16 hours of exposure to artificial light. It’s easy to figure out the characteristics of high-light, medium-light and low-light plants from the seed packet you got.
Here is a guide that you may use if your plants don’t indicate how much light they need:
- Araucaria Plant
- Schefflera Arboricola
- Ponytail Palm Tree
- Yucca Plant
- Ficus Benjamina
- Ming Aralia Plant
- Ficus Pandurata
- Codiaeum Petra
- Chrysalidocarpus Lutescens
- Aloe Vera
- Burro Tail
- African Violet
- Bird’s Nest Fern
- Boston Fern
- Dumb Cane
- Moth Orchid
- Moon Valley Pilea
- Chinese Money Plant
- Maidenhair Fern
- Staghorn Fern
- Snake Plant
- Asparagus Fern
- Weeping Fig
- Elephant’s Ear
- Bear’s Paw Fern
- Earth Star
There are a few plants that fall into these categories. Take note of these to help you decide how long to turn your grow lights on and off.
What Happens When Plants Are Overexposed to Light?
When plants are exposed to too much light, their energy production will exceed their ability to handle it.
Plants that remain under grow lights for too long will end up dead and wilted. Yellow spots on leaves indicate that a plant has absorbed too much light.
However, you can still correct the yellow spots on leaves of your plants or crops by reducing their exposure to light.
Please make sure to do this before it’s too late!
What Happens to Plants When They Aren’t Exposed To Light?
In direct response to this question, your plants will not survive as they will not be able to undergo photosynthesis to produce enough energy to thrive.
Getting a backup generator for your grow lights would be highly recommended if you’re an indoor grower with a wide variety of plants and crops. Check out our indoor growing guide for more information!
The Other Things You Need To Know When Growing Plants Under Grow Lights
Growing plants indoors, light exposure greatly matters, but there are also plenty of other factors to consider when choosing grow lights.
Here are some things to consider.
You may think that using only one shade or spectrum of light is alright since sunlight only appears one color.
This could work, but if you want your plants to grow healthy and of good quality, you’ll need to know how different colors affect plant growth.
You can use fluorescent bulbs with white and yellow shades to deliver what the plants need.
While you may also use incandescent bulbs in your grow room setup, you should keep in mind that these bulbs only deliver warmth or the red spectrum.
Aside from that, it produces more heat and is more prone to dying out.
Indoors, you can buy LED grow lights with literal red and blue lights to cater to your plants’ needs.
The LED bulbs don’t produce much heat, so they can be an excellent choice for maintaining the humidity in the grow room.
Optimize your plant’s health and growth by measuring the light intensity.
When it comes to grow lights, light intensity should also be considered, along with heat.
The distance between your grow lights and crops determines the intensity of the light in your grow room. Here is a complete guide about how far grow lights should be from crops.
Several growers install these lights in such a way that they can adjust the distance between their plants, but others leave the spacing as is by installing the lights within main frames.
It is very important to know your plant types when it comes to knowing what intensity it requires. If your plants are low, medium, or high-light plants, you will know what intensity they need.
Medium-light plants only require 250 feet of candles. This means that’s what they need in terms of light and heat intensity.
If you have a high-light plant, you need at least 1000 feet of candles to make it thrive. If you have a low-light plant, just having light exposure is enough.
If you want to be successful at growing crops or plants indoors, you need to put in a good deal of effort and planning.
When it comes to the light exposure of the plants you are growing, it can be difficult to establish a routine if it is not automated, so you should plan accordingly.
The most important thing to do first is to identify the type of plant you have so that you can cater to its needs.
It is crucial to keep in mind the light intensity and time exposure when growing plants, so get yourself ready!
Growing houseplants can be a fun hobby and even an income source. It shouldn’t be stressful or impossible, as long as you know what to do. Have fun and good luck!
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