You probably already know that plants need light to grow.
But what kind of light is best? Natural sunlight, part-shade, artificial light?
There are a lot of options, and the answer depends on the type of plants you’re growing.
For most plants, full-spectrum artificial light or natural sunlight produce the best growth. This is true for all stages of plant growth: vegetative growth of seeds, stems, & roots, as well as flowering, and producing fruit. However, excessive UV light can damage plants and their DNA.
So, get your cheap sunglasses, and get ready to dig into the straight scoop on what kind of light & colors make plants grow best.
What light is best for plant growth?
OK, so you’ve probably heard of grow lights vs. natural sunlight.
Is there any difference on plant growth?
Like anything, the answer depends.
For optimal plant growth, full-spectrum artificial light or natural sunlight are the best options.
Direct sunlight is ideal for most plants, since it provides a full spectrum of light–including UV and blue light (which is essential for strong growth and healthy development).
However, some plants–like ferns and leafy greens–do better in partial shade, especially in areas with intense sunlight.
For indoor plants or in areas where natural sunlight is limited, artificial light can be used.
Full-spectrum LED lights or fluorescent lights are good options, since they can mimic the natural light spectrum, and provide the right wavelengths of light for plant growth.
It’s important to place the lights close enough to the plants and to provide a consistent light source for several hours per day.
Check out our complete guide on the optimal distance of grow lights for plants.
UV and blue light are essential for strong growth and healthy development of plants because they play important roles in photosynthesis and phototropism.
If you don’t already know, photosynthesis is the process by which plants convert light energy into chemical energy.
See our article on the purpose of photosynthesis.
UV light can help increase the production of chlorophyll, which is essential for photosynthesis.
Blue light is also important because it helps regulate the growth and development of the plant.
For example, blue light helps control the formation of stems and leaves, and the direction of growth.
Do plants grow better with sunlight or artificial light?
But what about the debate about using sunlight or artificial light?
Is there a clear winner?
Plants can grow well under both sunlight & artificial light, as long as the light source provides full-spectrum light. Both red & blue light are important for plant growth. However, sunlight can also be intense & cause damage to some plants.
Compared to sunlight, artificial light allows growers to control the intensity and spectrum of light, which can be beneficial for plants that require specific light conditions to thrive.
For example, some plants may benefit from more blue light for healthy stem and leaf growth, while others may need more red light to promote flowering and fruiting.
When it comes to growing plants under artificial light, there’s no one-size-fits-all answer.
Different plants have different light requirements, so it really depends on what you’re growing.
Plants that are commonly grown under artificial lights are:
Salad greens and other leafy veggies
If you’re into indoor hydroponic gardening, you’ll be happy to know that lettuce and other greens can grow well under artificial lights.
The key is to provide bright light with a balanced mix of blue and red light.
Check out our complete guide to growing lettuce hydroponically.
Fresh herbs are always a staple in the kitchen.
And growing them indoors under artificial lights can be a great option.
Basil, cilantro, parsley, and more can thrive under bright, balanced light that includes blue and red light.
Succulents and cacti
These trendy houseplants can also do well under artificial lights, as long as they get bright light with a good amount of blue light.
Orchids can be a bit finicky.
But with the right lights, they can thrive indoors.
Just make sure to provide bright light with a good amount of blue light.
Check out our complete guide to growing orchids.
So, it really depends on what you’re growing.
Do your research and find out the specific light requirements for the plants you want to grow.
And don’t forget to keep an eye on the light intensity and spectrum to make sure your plants are getting the best light possible for healthy growth.
What light color is best for plant growth?
If that doesn’t ring a bell, it’s simply an acronym for the colors of light in the visible spectrum: red, orange, yellow, green, blue, indigo, & violet.
OK, so which color light is the best for plant growth?
The best light color is the full spectrum of light, including blue & red light, since these are most important for overall plant growth. Green and yellow aren’t absorbed as well by plants, but they can still contribute to overall growth by increasing the light intensity that reaches the plant.
So, generally speaking, blue & red light colors contribute most to plant growth.
Blue light promotes healthy leaf and stem growth, while red light promotes flowering and fruiting.
Both of these wavelengths of light are important for the overall growth and development of the plant.
Here’s a list of different types of plant growth and the color of light that is typically best for each stage:
- Leaves and stem growth: Blue light (wavelengths of 400-500 nm) promotes healthy leaf and stem growth by promoting chlorophyll synthesis, as well as other pigments involved in photosynthesis.
- Flowering: Red light (wavelengths of 600-700 nm) promotes flowering by stimulating the production of floral hormones. This is why many growers provide plants with additional red light during the flowering stage to encourage stronger and more robust blooms.
- Fruiting: Like flowering, red light is also important for fruiting, as it stimulates the production of hormones that are involved in fruit development.
Check out our more complete article on how the color of light affects plant growth.
What plants don’t do well in red and blue light?
Some plant varieties may not do well under red & blue light, and may prefer a more balanced light spectrum, including more yellow and green light.
This can occur because the plant’s physiology may be adapted to different light conditions, and certain wavelengths of light may not be absorbed as effectively by the plant.
For example, shade-tolerant plants such as ferns, mosses, and some understory forest plants, may not grow well under intense blue and red light, since they’re adapted to low light conditions.
These plants may benefit from a more balanced light spectrum that includes more green and yellow light, which can provide a more natural light environment for them to grow in.
What color light is worst for plant growth?
Right, so red & blue are best for growth, but is there a color that’s BAD for plant growth?
There’s no one color of light that’s “worst” for plant growth. However, some studies have shown that plants can be sensitive to certain wavelengths of light, particularly those in the ultraviolet (UV) range–especially intense or prolonged UV exposure.
Excessive UV light can cause damage to the plant’s tissues.
That UV damage can lead to reduced growth, chlorosis, and stunted development.
This can occur because UV light can disrupt the plant’s cellular processes and damage the plant’s DNA.
It’s also important to note that too much light of any kind, regardless of color, can be harmful to plants, as it can cause photoinhibition, where the plant becomes unable to effectively photosynthesize.
So, for UV, plants are kinda like us: they might need a little sunscreen to prevent damage.
Check out our guide to what kind of shade cloth to use.
How does light affect plant growth?
OK, so red & blue light produce the best plant growth.
But how specifically does light affect plant growth?
Like, what is light actually doing?
Light provides energy for the process of photosynthesis. During photosynthesis, plants use energy from light to convert carbon dioxide and water into sugars and oxygen. These sugars serve as the plant’s food, fueling its growth and development.
Check out our article on the outputs of photosynthesis.
Different wavelengths of light can have different effects on plants.
Blue light, for example, promotes healthy leaf and stem growth.
Red light promotes flowering and fruiting.
UV light can damage plant tissues and reduce growth.
Excess light of any color can cause photoinhibition, where the plant becomes unable to effectively photosynthesize.
Light also affects other aspects of plant growth. For example:
- Phototropism: where the plant grows towards or away from light.
- Photoperiodism: where the plant’s growth and development are influenced by the length of the day.
Overall, light plays a crucial role in determining the overall health and growth of a plant.
To sum up, both natural sunlight & artificial light can allow plants to grow well–especially if the artificial light produces both red & blue light.
While red & blue light are most important for plant growth, excessive UV light can damage plants.
Light is essential for plant growth because it provides the energy for photosynthesis: where plants combine oxygen, water, and carbon dioxide into sugar (i.e., food) for the plant.